2005-04-17 06:20:36 +08:00
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------------------------------------------------------------------------------
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T H E /proc F I L E S Y S T E M
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------------------------------------------------------------------------------
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/proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999
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Bodo Bauer <bb@ricochet.net>
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2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
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2009-04-03 07:57:20 +08:00
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move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
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2005-04-17 06:20:36 +08:00
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------------------------------------------------------------------------------
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Version 1.3 Kernel version 2.2.12
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Kernel version 2.4.0-test11-pre4
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------------------------------------------------------------------------------
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Table of Contents
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-----------------
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0 Preface
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0.1 Introduction/Credits
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0.2 Legal Stuff
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1 Collecting System Information
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1.1 Process-Specific Subdirectories
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1.2 Kernel data
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1.3 IDE devices in /proc/ide
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1.4 Networking info in /proc/net
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1.5 SCSI info
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1.6 Parallel port info in /proc/parport
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1.7 TTY info in /proc/tty
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1.8 Miscellaneous kernel statistics in /proc/stat
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2009-04-03 07:57:20 +08:00
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1.9 Ext4 file system parameters
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2005-04-17 06:20:36 +08:00
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2 Modifying System Parameters
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2009-04-03 07:57:20 +08:00
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3 Per-Process Parameters
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3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
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3.2 /proc/<pid>/oom_score - Display current oom-killer score
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3.3 /proc/<pid>/io - Display the IO accounting fields
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3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
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3.5 /proc/<pid>/mountinfo - Information about mounts
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2005-04-17 06:20:36 +08:00
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------------------------------------------------------------------------------
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Preface
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------------------------------------------------------------------------------
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0.1 Introduction/Credits
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------------------------
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This documentation is part of a soon (or so we hope) to be released book on
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the SuSE Linux distribution. As there is no complete documentation for the
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/proc file system and we've used many freely available sources to write these
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chapters, it seems only fair to give the work back to the Linux community.
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This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm
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afraid it's still far from complete, but we hope it will be useful. As far as
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we know, it is the first 'all-in-one' document about the /proc file system. It
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is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
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SPARC, AXP, etc., features, you probably won't find what you are looking for.
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It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
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additions and patches are welcome and will be added to this document if you
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mail them to Bodo.
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We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
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other people for help compiling this documentation. We'd also like to extend a
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special thank you to Andi Kleen for documentation, which we relied on heavily
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to create this document, as well as the additional information he provided.
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Thanks to everybody else who contributed source or docs to the Linux kernel
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and helped create a great piece of software... :)
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If you have any comments, corrections or additions, please don't hesitate to
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contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
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document.
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The latest version of this document is available online at
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http://skaro.nightcrawler.com/~bb/Docs/Proc as HTML version.
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If the above direction does not works for you, ypu could try the kernel
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mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
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comandante@zaralinux.com.
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0.2 Legal Stuff
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---------------
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We don't guarantee the correctness of this document, and if you come to us
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complaining about how you screwed up your system because of incorrect
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documentation, we won't feel responsible...
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------------------------------------------------------------------------------
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CHAPTER 1: COLLECTING SYSTEM INFORMATION
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------------------------------------------------------------------------------
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------------------------------------------------------------------------------
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In This Chapter
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------------------------------------------------------------------------------
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* Investigating the properties of the pseudo file system /proc and its
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ability to provide information on the running Linux system
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* Examining /proc's structure
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* Uncovering various information about the kernel and the processes running
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on the system
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------------------------------------------------------------------------------
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The proc file system acts as an interface to internal data structures in the
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kernel. It can be used to obtain information about the system and to change
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certain kernel parameters at runtime (sysctl).
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First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
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show you how you can use /proc/sys to change settings.
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1.1 Process-Specific Subdirectories
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-----------------------------------
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The directory /proc contains (among other things) one subdirectory for each
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process running on the system, which is named after the process ID (PID).
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The link self points to the process reading the file system. Each process
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subdirectory has the entries listed in Table 1-1.
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Table 1-1: Process specific entries in /proc
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..............................................................................
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2007-05-07 05:49:24 +08:00
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File Content
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clear_refs Clears page referenced bits shown in smaps output
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cmdline Command line arguments
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cpu Current and last cpu in which it was executed (2.4)(smp)
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cwd Link to the current working directory
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environ Values of environment variables
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exe Link to the executable of this process
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fd Directory, which contains all file descriptors
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maps Memory maps to executables and library files (2.4)
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mem Memory held by this process
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root Link to the root directory of this process
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stat Process status
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statm Process memory status information
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status Process status in human readable form
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wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
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2008-11-10 16:26:08 +08:00
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stack Report full stack trace, enable via CONFIG_STACKTRACE
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2007-05-07 05:49:24 +08:00
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smaps Extension based on maps, the rss size for each mapped file
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2005-04-17 06:20:36 +08:00
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..............................................................................
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For example, to get the status information of a process, all you have to do is
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read the file /proc/PID/status:
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>cat /proc/self/status
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Name: cat
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State: R (running)
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Pid: 5452
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PPid: 743
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TracerPid: 0 (2.4)
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Uid: 501 501 501 501
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Gid: 100 100 100 100
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Groups: 100 14 16
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VmSize: 1112 kB
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VmLck: 0 kB
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VmRSS: 348 kB
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VmData: 24 kB
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VmStk: 12 kB
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VmExe: 8 kB
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VmLib: 1044 kB
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SigPnd: 0000000000000000
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SigBlk: 0000000000000000
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SigIgn: 0000000000000000
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SigCgt: 0000000000000000
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CapInh: 00000000fffffeff
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CapPrm: 0000000000000000
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CapEff: 0000000000000000
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This shows you nearly the same information you would get if you viewed it with
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the ps command. In fact, ps uses the proc file system to obtain its
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information. The statm file contains more detailed information about the
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2007-07-16 14:40:38 +08:00
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process memory usage. Its seven fields are explained in Table 1-2. The stat
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file contains details information about the process itself. Its fields are
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explained in Table 1-3.
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2005-04-17 06:20:36 +08:00
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Table 1-2: Contents of the statm files (as of 2.6.8-rc3)
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..............................................................................
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Field Content
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size total program size (pages) (same as VmSize in status)
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resident size of memory portions (pages) (same as VmRSS in status)
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shared number of pages that are shared (i.e. backed by a file)
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trs number of pages that are 'code' (not including libs; broken,
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includes data segment)
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lrs number of pages of library (always 0 on 2.6)
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drs number of pages of data/stack (including libs; broken,
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includes library text)
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dt number of dirty pages (always 0 on 2.6)
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..............................................................................
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2007-07-16 14:40:38 +08:00
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Table 1-3: Contents of the stat files (as of 2.6.22-rc3)
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..............................................................................
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Field Content
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pid process id
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tcomm filename of the executable
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state state (R is running, S is sleeping, D is sleeping in an
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uninterruptible wait, Z is zombie, T is traced or stopped)
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ppid process id of the parent process
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pgrp pgrp of the process
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sid session id
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tty_nr tty the process uses
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tty_pgrp pgrp of the tty
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flags task flags
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min_flt number of minor faults
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cmin_flt number of minor faults with child's
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maj_flt number of major faults
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cmaj_flt number of major faults with child's
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utime user mode jiffies
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stime kernel mode jiffies
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cutime user mode jiffies with child's
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cstime kernel mode jiffies with child's
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priority priority level
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nice nice level
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num_threads number of threads
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2008-02-03 22:17:16 +08:00
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it_real_value (obsolete, always 0)
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2007-07-16 14:40:38 +08:00
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start_time time the process started after system boot
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vsize virtual memory size
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rss resident set memory size
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rsslim current limit in bytes on the rss
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start_code address above which program text can run
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end_code address below which program text can run
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start_stack address of the start of the stack
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esp current value of ESP
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eip current value of EIP
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pending bitmap of pending signals (obsolete)
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blocked bitmap of blocked signals (obsolete)
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sigign bitmap of ignored signals (obsolete)
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sigcatch bitmap of catched signals (obsolete)
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wchan address where process went to sleep
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0 (place holder)
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0 (place holder)
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exit_signal signal to send to parent thread on exit
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task_cpu which CPU the task is scheduled on
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rt_priority realtime priority
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policy scheduling policy (man sched_setscheduler)
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blkio_ticks time spent waiting for block IO
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..............................................................................
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2005-04-17 06:20:36 +08:00
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1.2 Kernel data
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---------------
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Similar to the process entries, the kernel data files give information about
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the running kernel. The files used to obtain this information are contained in
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2007-07-16 14:40:38 +08:00
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/proc and are listed in Table 1-4. Not all of these will be present in your
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2005-04-17 06:20:36 +08:00
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system. It depends on the kernel configuration and the loaded modules, which
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files are there, and which are missing.
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2007-07-16 14:40:38 +08:00
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Table 1-4: Kernel info in /proc
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2005-04-17 06:20:36 +08:00
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..............................................................................
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File Content
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apm Advanced power management info
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buddyinfo Kernel memory allocator information (see text) (2.5)
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bus Directory containing bus specific information
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cmdline Kernel command line
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cpuinfo Info about the CPU
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devices Available devices (block and character)
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dma Used DMS channels
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filesystems Supported filesystems
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driver Various drivers grouped here, currently rtc (2.4)
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execdomains Execdomains, related to security (2.4)
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fb Frame Buffer devices (2.4)
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fs File system parameters, currently nfs/exports (2.4)
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ide Directory containing info about the IDE subsystem
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interrupts Interrupt usage
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iomem Memory map (2.4)
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ioports I/O port usage
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irq Masks for irq to cpu affinity (2.4)(smp?)
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isapnp ISA PnP (Plug&Play) Info (2.4)
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kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
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kmsg Kernel messages
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ksyms Kernel symbol table
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loadavg Load average of last 1, 5 & 15 minutes
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locks Kernel locks
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meminfo Memory info
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misc Miscellaneous
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modules List of loaded modules
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mounts Mounted filesystems
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net Networking info (see text)
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partitions Table of partitions known to the system
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2007-05-09 13:19:14 +08:00
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pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
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2005-04-17 06:20:36 +08:00
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decoupled by lspci (2.4)
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rtc Real time clock
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scsi SCSI info (see text)
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slabinfo Slab pool info
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stat Overall statistics
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swaps Swap space utilization
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sys See chapter 2
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sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
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tty Info of tty drivers
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uptime System uptime
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version Kernel version
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video bttv info of video resources (2.4)
|
2008-07-24 12:27:38 +08:00
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vmallocinfo Show vmalloced areas
|
2005-04-17 06:20:36 +08:00
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..............................................................................
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You can, for example, check which interrupts are currently in use and what
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they are used for by looking in the file /proc/interrupts:
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> cat /proc/interrupts
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CPU0
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0: 8728810 XT-PIC timer
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1: 895 XT-PIC keyboard
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2: 0 XT-PIC cascade
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3: 531695 XT-PIC aha152x
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4: 2014133 XT-PIC serial
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5: 44401 XT-PIC pcnet_cs
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8: 2 XT-PIC rtc
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11: 8 XT-PIC i82365
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12: 182918 XT-PIC PS/2 Mouse
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13: 1 XT-PIC fpu
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14: 1232265 XT-PIC ide0
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15: 7 XT-PIC ide1
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NMI: 0
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In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
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output of a SMP machine):
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> cat /proc/interrupts
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CPU0 CPU1
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0: 1243498 1214548 IO-APIC-edge timer
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1: 8949 8958 IO-APIC-edge keyboard
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2: 0 0 XT-PIC cascade
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5: 11286 10161 IO-APIC-edge soundblaster
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8: 1 0 IO-APIC-edge rtc
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9: 27422 27407 IO-APIC-edge 3c503
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12: 113645 113873 IO-APIC-edge PS/2 Mouse
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13: 0 0 XT-PIC fpu
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14: 22491 24012 IO-APIC-edge ide0
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15: 2183 2415 IO-APIC-edge ide1
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17: 30564 30414 IO-APIC-level eth0
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18: 177 164 IO-APIC-level bttv
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NMI: 2457961 2457959
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LOC: 2457882 2457881
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ERR: 2155
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NMI is incremented in this case because every timer interrupt generates a NMI
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(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
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LOC is the local interrupt counter of the internal APIC of every CPU.
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ERR is incremented in the case of errors in the IO-APIC bus (the bus that
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connects the CPUs in a SMP system. This means that an error has been detected,
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the IO-APIC automatically retry the transmission, so it should not be a big
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problem, but you should read the SMP-FAQ.
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|
|
|
2007-10-18 00:04:40 +08:00
|
|
|
In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
|
|
|
|
/proc/interrupts to display every IRQ vector in use by the system, not
|
|
|
|
just those considered 'most important'. The new vectors are:
|
|
|
|
|
|
|
|
THR -- interrupt raised when a machine check threshold counter
|
|
|
|
(typically counting ECC corrected errors of memory or cache) exceeds
|
|
|
|
a configurable threshold. Only available on some systems.
|
|
|
|
|
|
|
|
TRM -- a thermal event interrupt occurs when a temperature threshold
|
|
|
|
has been exceeded for the CPU. This interrupt may also be generated
|
|
|
|
when the temperature drops back to normal.
|
|
|
|
|
|
|
|
SPU -- a spurious interrupt is some interrupt that was raised then lowered
|
|
|
|
by some IO device before it could be fully processed by the APIC. Hence
|
|
|
|
the APIC sees the interrupt but does not know what device it came from.
|
|
|
|
For this case the APIC will generate the interrupt with a IRQ vector
|
|
|
|
of 0xff. This might also be generated by chipset bugs.
|
|
|
|
|
|
|
|
RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are
|
|
|
|
sent from one CPU to another per the needs of the OS. Typically,
|
|
|
|
their statistics are used by kernel developers and interested users to
|
|
|
|
determine the occurance of interrupt of the given type.
|
|
|
|
|
|
|
|
The above IRQ vectors are displayed only when relevent. For example,
|
|
|
|
the threshold vector does not exist on x86_64 platforms. Others are
|
|
|
|
suppressed when the system is a uniprocessor. As of this writing, only
|
|
|
|
i386 and x86_64 platforms support the new IRQ vector displays.
|
|
|
|
|
|
|
|
Of some interest is the introduction of the /proc/irq directory to 2.4.
|
2005-04-17 06:20:36 +08:00
|
|
|
It could be used to set IRQ to CPU affinity, this means that you can "hook" an
|
|
|
|
IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
|
2008-05-30 02:02:52 +08:00
|
|
|
irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
|
|
|
|
prof_cpu_mask.
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
For example
|
|
|
|
> ls /proc/irq/
|
|
|
|
0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
|
2008-05-30 02:02:52 +08:00
|
|
|
1 11 13 15 17 19 3 5 7 9 default_smp_affinity
|
2005-04-17 06:20:36 +08:00
|
|
|
> ls /proc/irq/0/
|
|
|
|
smp_affinity
|
|
|
|
|
2008-05-30 02:02:52 +08:00
|
|
|
smp_affinity is a bitmask, in which you can specify which CPUs can handle the
|
|
|
|
IRQ, you can set it by doing:
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-05-30 02:02:52 +08:00
|
|
|
> echo 1 > /proc/irq/10/smp_affinity
|
|
|
|
|
|
|
|
This means that only the first CPU will handle the IRQ, but you can also echo
|
|
|
|
5 which means that only the first and fourth CPU can handle the IRQ.
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-05-30 02:02:52 +08:00
|
|
|
The contents of each smp_affinity file is the same by default:
|
|
|
|
|
|
|
|
> cat /proc/irq/0/smp_affinity
|
|
|
|
ffffffff
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-05-30 02:02:52 +08:00
|
|
|
The default_smp_affinity mask applies to all non-active IRQs, which are the
|
|
|
|
IRQs which have not yet been allocated/activated, and hence which lack a
|
|
|
|
/proc/irq/[0-9]* directory.
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-05-30 02:02:52 +08:00
|
|
|
prof_cpu_mask specifies which CPUs are to be profiled by the system wide
|
|
|
|
profiler. Default value is ffffffff (all cpus).
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
|
|
|
|
between all the CPUs which are allowed to handle it. As usual the kernel has
|
|
|
|
more info than you and does a better job than you, so the defaults are the
|
|
|
|
best choice for almost everyone.
|
|
|
|
|
|
|
|
There are three more important subdirectories in /proc: net, scsi, and sys.
|
|
|
|
The general rule is that the contents, or even the existence of these
|
|
|
|
directories, depend on your kernel configuration. If SCSI is not enabled, the
|
|
|
|
directory scsi may not exist. The same is true with the net, which is there
|
|
|
|
only when networking support is present in the running kernel.
|
|
|
|
|
|
|
|
The slabinfo file gives information about memory usage at the slab level.
|
|
|
|
Linux uses slab pools for memory management above page level in version 2.2.
|
|
|
|
Commonly used objects have their own slab pool (such as network buffers,
|
|
|
|
directory cache, and so on).
|
|
|
|
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
> cat /proc/buddyinfo
|
|
|
|
|
|
|
|
Node 0, zone DMA 0 4 5 4 4 3 ...
|
|
|
|
Node 0, zone Normal 1 0 0 1 101 8 ...
|
|
|
|
Node 0, zone HighMem 2 0 0 1 1 0 ...
|
|
|
|
|
|
|
|
Memory fragmentation is a problem under some workloads, and buddyinfo is a
|
|
|
|
useful tool for helping diagnose these problems. Buddyinfo will give you a
|
|
|
|
clue as to how big an area you can safely allocate, or why a previous
|
|
|
|
allocation failed.
|
|
|
|
|
|
|
|
Each column represents the number of pages of a certain order which are
|
|
|
|
available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
|
|
|
|
ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
|
|
|
|
available in ZONE_NORMAL, etc...
|
|
|
|
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
meminfo:
|
|
|
|
|
|
|
|
Provides information about distribution and utilization of memory. This
|
|
|
|
varies by architecture and compile options. The following is from a
|
|
|
|
16GB PIII, which has highmem enabled. You may not have all of these fields.
|
|
|
|
|
|
|
|
> cat /proc/meminfo
|
|
|
|
|
|
|
|
|
|
|
|
MemTotal: 16344972 kB
|
|
|
|
MemFree: 13634064 kB
|
|
|
|
Buffers: 3656 kB
|
|
|
|
Cached: 1195708 kB
|
|
|
|
SwapCached: 0 kB
|
|
|
|
Active: 891636 kB
|
|
|
|
Inactive: 1077224 kB
|
|
|
|
HighTotal: 15597528 kB
|
|
|
|
HighFree: 13629632 kB
|
|
|
|
LowTotal: 747444 kB
|
|
|
|
LowFree: 4432 kB
|
|
|
|
SwapTotal: 0 kB
|
|
|
|
SwapFree: 0 kB
|
|
|
|
Dirty: 968 kB
|
|
|
|
Writeback: 0 kB
|
2008-04-30 15:54:39 +08:00
|
|
|
AnonPages: 861800 kB
|
2005-04-17 06:20:36 +08:00
|
|
|
Mapped: 280372 kB
|
2008-04-30 15:54:39 +08:00
|
|
|
Slab: 284364 kB
|
|
|
|
SReclaimable: 159856 kB
|
|
|
|
SUnreclaim: 124508 kB
|
|
|
|
PageTables: 24448 kB
|
|
|
|
NFS_Unstable: 0 kB
|
|
|
|
Bounce: 0 kB
|
|
|
|
WritebackTmp: 0 kB
|
2005-04-17 06:20:36 +08:00
|
|
|
CommitLimit: 7669796 kB
|
|
|
|
Committed_AS: 100056 kB
|
|
|
|
VmallocTotal: 112216 kB
|
|
|
|
VmallocUsed: 428 kB
|
|
|
|
VmallocChunk: 111088 kB
|
|
|
|
|
|
|
|
MemTotal: Total usable ram (i.e. physical ram minus a few reserved
|
|
|
|
bits and the kernel binary code)
|
|
|
|
MemFree: The sum of LowFree+HighFree
|
|
|
|
Buffers: Relatively temporary storage for raw disk blocks
|
|
|
|
shouldn't get tremendously large (20MB or so)
|
|
|
|
Cached: in-memory cache for files read from the disk (the
|
|
|
|
pagecache). Doesn't include SwapCached
|
|
|
|
SwapCached: Memory that once was swapped out, is swapped back in but
|
|
|
|
still also is in the swapfile (if memory is needed it
|
|
|
|
doesn't need to be swapped out AGAIN because it is already
|
|
|
|
in the swapfile. This saves I/O)
|
|
|
|
Active: Memory that has been used more recently and usually not
|
|
|
|
reclaimed unless absolutely necessary.
|
|
|
|
Inactive: Memory which has been less recently used. It is more
|
|
|
|
eligible to be reclaimed for other purposes
|
|
|
|
HighTotal:
|
|
|
|
HighFree: Highmem is all memory above ~860MB of physical memory
|
|
|
|
Highmem areas are for use by userspace programs, or
|
|
|
|
for the pagecache. The kernel must use tricks to access
|
|
|
|
this memory, making it slower to access than lowmem.
|
|
|
|
LowTotal:
|
|
|
|
LowFree: Lowmem is memory which can be used for everything that
|
2006-10-04 04:45:33 +08:00
|
|
|
highmem can be used for, but it is also available for the
|
2005-04-17 06:20:36 +08:00
|
|
|
kernel's use for its own data structures. Among many
|
|
|
|
other things, it is where everything from the Slab is
|
|
|
|
allocated. Bad things happen when you're out of lowmem.
|
|
|
|
SwapTotal: total amount of swap space available
|
|
|
|
SwapFree: Memory which has been evicted from RAM, and is temporarily
|
|
|
|
on the disk
|
|
|
|
Dirty: Memory which is waiting to get written back to the disk
|
|
|
|
Writeback: Memory which is actively being written back to the disk
|
2008-04-30 15:54:39 +08:00
|
|
|
AnonPages: Non-file backed pages mapped into userspace page tables
|
2005-04-17 06:20:36 +08:00
|
|
|
Mapped: files which have been mmaped, such as libraries
|
2006-01-10 07:20:30 +08:00
|
|
|
Slab: in-kernel data structures cache
|
2008-04-30 15:54:39 +08:00
|
|
|
SReclaimable: Part of Slab, that might be reclaimed, such as caches
|
|
|
|
SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
|
|
|
|
PageTables: amount of memory dedicated to the lowest level of page
|
|
|
|
tables.
|
|
|
|
NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
|
|
|
|
storage
|
|
|
|
Bounce: Memory used for block device "bounce buffers"
|
|
|
|
WritebackTmp: Memory used by FUSE for temporary writeback buffers
|
2005-04-17 06:20:36 +08:00
|
|
|
CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
|
|
|
|
this is the total amount of memory currently available to
|
|
|
|
be allocated on the system. This limit is only adhered to
|
|
|
|
if strict overcommit accounting is enabled (mode 2 in
|
|
|
|
'vm.overcommit_memory').
|
|
|
|
The CommitLimit is calculated with the following formula:
|
|
|
|
CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
|
|
|
|
For example, on a system with 1G of physical RAM and 7G
|
|
|
|
of swap with a `vm.overcommit_ratio` of 30 it would
|
|
|
|
yield a CommitLimit of 7.3G.
|
|
|
|
For more details, see the memory overcommit documentation
|
|
|
|
in vm/overcommit-accounting.
|
|
|
|
Committed_AS: The amount of memory presently allocated on the system.
|
|
|
|
The committed memory is a sum of all of the memory which
|
|
|
|
has been allocated by processes, even if it has not been
|
|
|
|
"used" by them as of yet. A process which malloc()'s 1G
|
|
|
|
of memory, but only touches 300M of it will only show up
|
|
|
|
as using 300M of memory even if it has the address space
|
|
|
|
allocated for the entire 1G. This 1G is memory which has
|
|
|
|
been "committed" to by the VM and can be used at any time
|
|
|
|
by the allocating application. With strict overcommit
|
|
|
|
enabled on the system (mode 2 in 'vm.overcommit_memory'),
|
|
|
|
allocations which would exceed the CommitLimit (detailed
|
|
|
|
above) will not be permitted. This is useful if one needs
|
|
|
|
to guarantee that processes will not fail due to lack of
|
|
|
|
memory once that memory has been successfully allocated.
|
|
|
|
VmallocTotal: total size of vmalloc memory area
|
|
|
|
VmallocUsed: amount of vmalloc area which is used
|
|
|
|
VmallocChunk: largest contigious block of vmalloc area which is free
|
|
|
|
|
2008-07-24 12:27:38 +08:00
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
vmallocinfo:
|
|
|
|
|
|
|
|
Provides information about vmalloced/vmaped areas. One line per area,
|
|
|
|
containing the virtual address range of the area, size in bytes,
|
|
|
|
caller information of the creator, and optional information depending
|
|
|
|
on the kind of area :
|
|
|
|
|
|
|
|
pages=nr number of pages
|
|
|
|
phys=addr if a physical address was specified
|
|
|
|
ioremap I/O mapping (ioremap() and friends)
|
|
|
|
vmalloc vmalloc() area
|
|
|
|
vmap vmap()ed pages
|
|
|
|
user VM_USERMAP area
|
|
|
|
vpages buffer for pages pointers was vmalloced (huge area)
|
|
|
|
N<node>=nr (Only on NUMA kernels)
|
|
|
|
Number of pages allocated on memory node <node>
|
|
|
|
|
|
|
|
> cat /proc/vmallocinfo
|
|
|
|
0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
|
|
|
|
/0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
|
|
|
|
0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
|
|
|
|
/0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
|
|
|
|
0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
|
|
|
|
phys=7fee8000 ioremap
|
|
|
|
0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
|
|
|
|
phys=7fee7000 ioremap
|
|
|
|
0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
|
|
|
|
0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
|
|
|
|
/0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
|
|
|
|
0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
|
|
|
|
pages=2 vmalloc N1=2
|
|
|
|
0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
|
|
|
|
/0x130 [x_tables] pages=4 vmalloc N0=4
|
|
|
|
0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
|
|
|
|
pages=14 vmalloc N2=14
|
|
|
|
0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
|
|
|
|
pages=4 vmalloc N1=4
|
|
|
|
0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
|
|
|
|
pages=2 vmalloc N1=2
|
|
|
|
0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
|
|
|
|
pages=10 vmalloc N0=10
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
1.3 IDE devices in /proc/ide
|
|
|
|
----------------------------
|
|
|
|
|
|
|
|
The subdirectory /proc/ide contains information about all IDE devices of which
|
|
|
|
the kernel is aware. There is one subdirectory for each IDE controller, the
|
|
|
|
file drivers and a link for each IDE device, pointing to the device directory
|
|
|
|
in the controller specific subtree.
|
|
|
|
|
|
|
|
The file drivers contains general information about the drivers used for the
|
|
|
|
IDE devices:
|
|
|
|
|
|
|
|
> cat /proc/ide/drivers
|
|
|
|
ide-cdrom version 4.53
|
|
|
|
ide-disk version 1.08
|
|
|
|
|
|
|
|
More detailed information can be found in the controller specific
|
|
|
|
subdirectories. These are named ide0, ide1 and so on. Each of these
|
2007-07-16 14:40:38 +08:00
|
|
|
directories contains the files shown in table 1-5.
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
2007-07-16 14:40:38 +08:00
|
|
|
Table 1-5: IDE controller info in /proc/ide/ide?
|
2005-04-17 06:20:36 +08:00
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
channel IDE channel (0 or 1)
|
|
|
|
config Configuration (only for PCI/IDE bridge)
|
|
|
|
mate Mate name
|
|
|
|
model Type/Chipset of IDE controller
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
Each device connected to a controller has a separate subdirectory in the
|
2007-07-16 14:40:38 +08:00
|
|
|
controllers directory. The files listed in table 1-6 are contained in these
|
2005-04-17 06:20:36 +08:00
|
|
|
directories.
|
|
|
|
|
|
|
|
|
2007-07-16 14:40:38 +08:00
|
|
|
Table 1-6: IDE device information
|
2005-04-17 06:20:36 +08:00
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
cache The cache
|
|
|
|
capacity Capacity of the medium (in 512Byte blocks)
|
|
|
|
driver driver and version
|
|
|
|
geometry physical and logical geometry
|
|
|
|
identify device identify block
|
|
|
|
media media type
|
|
|
|
model device identifier
|
|
|
|
settings device setup
|
|
|
|
smart_thresholds IDE disk management thresholds
|
|
|
|
smart_values IDE disk management values
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
The most interesting file is settings. This file contains a nice overview of
|
|
|
|
the drive parameters:
|
|
|
|
|
|
|
|
# cat /proc/ide/ide0/hda/settings
|
|
|
|
name value min max mode
|
|
|
|
---- ----- --- --- ----
|
|
|
|
bios_cyl 526 0 65535 rw
|
|
|
|
bios_head 255 0 255 rw
|
|
|
|
bios_sect 63 0 63 rw
|
|
|
|
breada_readahead 4 0 127 rw
|
|
|
|
bswap 0 0 1 r
|
|
|
|
file_readahead 72 0 2097151 rw
|
|
|
|
io_32bit 0 0 3 rw
|
|
|
|
keepsettings 0 0 1 rw
|
|
|
|
max_kb_per_request 122 1 127 rw
|
|
|
|
multcount 0 0 8 rw
|
|
|
|
nice1 1 0 1 rw
|
|
|
|
nowerr 0 0 1 rw
|
|
|
|
pio_mode write-only 0 255 w
|
|
|
|
slow 0 0 1 rw
|
|
|
|
unmaskirq 0 0 1 rw
|
|
|
|
using_dma 0 0 1 rw
|
|
|
|
|
|
|
|
|
|
|
|
1.4 Networking info in /proc/net
|
|
|
|
--------------------------------
|
|
|
|
|
|
|
|
The subdirectory /proc/net follows the usual pattern. Table 1-6 shows the
|
|
|
|
additional values you get for IP version 6 if you configure the kernel to
|
|
|
|
support this. Table 1-7 lists the files and their meaning.
|
|
|
|
|
|
|
|
|
|
|
|
Table 1-6: IPv6 info in /proc/net
|
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
udp6 UDP sockets (IPv6)
|
|
|
|
tcp6 TCP sockets (IPv6)
|
|
|
|
raw6 Raw device statistics (IPv6)
|
|
|
|
igmp6 IP multicast addresses, which this host joined (IPv6)
|
|
|
|
if_inet6 List of IPv6 interface addresses
|
|
|
|
ipv6_route Kernel routing table for IPv6
|
|
|
|
rt6_stats Global IPv6 routing tables statistics
|
|
|
|
sockstat6 Socket statistics (IPv6)
|
|
|
|
snmp6 Snmp data (IPv6)
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
|
|
|
|
Table 1-7: Network info in /proc/net
|
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
arp Kernel ARP table
|
|
|
|
dev network devices with statistics
|
|
|
|
dev_mcast the Layer2 multicast groups a device is listening too
|
|
|
|
(interface index, label, number of references, number of bound
|
|
|
|
addresses).
|
|
|
|
dev_stat network device status
|
|
|
|
ip_fwchains Firewall chain linkage
|
|
|
|
ip_fwnames Firewall chain names
|
|
|
|
ip_masq Directory containing the masquerading tables
|
|
|
|
ip_masquerade Major masquerading table
|
|
|
|
netstat Network statistics
|
|
|
|
raw raw device statistics
|
|
|
|
route Kernel routing table
|
|
|
|
rpc Directory containing rpc info
|
|
|
|
rt_cache Routing cache
|
|
|
|
snmp SNMP data
|
|
|
|
sockstat Socket statistics
|
|
|
|
tcp TCP sockets
|
|
|
|
tr_rif Token ring RIF routing table
|
|
|
|
udp UDP sockets
|
|
|
|
unix UNIX domain sockets
|
|
|
|
wireless Wireless interface data (Wavelan etc)
|
|
|
|
igmp IP multicast addresses, which this host joined
|
|
|
|
psched Global packet scheduler parameters.
|
|
|
|
netlink List of PF_NETLINK sockets
|
|
|
|
ip_mr_vifs List of multicast virtual interfaces
|
|
|
|
ip_mr_cache List of multicast routing cache
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
You can use this information to see which network devices are available in
|
|
|
|
your system and how much traffic was routed over those devices:
|
|
|
|
|
|
|
|
> cat /proc/net/dev
|
|
|
|
Inter-|Receive |[...
|
|
|
|
face |bytes packets errs drop fifo frame compressed multicast|[...
|
|
|
|
lo: 908188 5596 0 0 0 0 0 0 [...
|
|
|
|
ppp0:15475140 20721 410 0 0 410 0 0 [...
|
|
|
|
eth0: 614530 7085 0 0 0 0 0 1 [...
|
|
|
|
|
|
|
|
...] Transmit
|
|
|
|
...] bytes packets errs drop fifo colls carrier compressed
|
|
|
|
...] 908188 5596 0 0 0 0 0 0
|
|
|
|
...] 1375103 17405 0 0 0 0 0 0
|
|
|
|
...] 1703981 5535 0 0 0 3 0 0
|
|
|
|
|
|
|
|
In addition, each Channel Bond interface has it's own directory. For
|
|
|
|
example, the bond0 device will have a directory called /proc/net/bond0/.
|
|
|
|
It will contain information that is specific to that bond, such as the
|
|
|
|
current slaves of the bond, the link status of the slaves, and how
|
|
|
|
many times the slaves link has failed.
|
|
|
|
|
|
|
|
1.5 SCSI info
|
|
|
|
-------------
|
|
|
|
|
|
|
|
If you have a SCSI host adapter in your system, you'll find a subdirectory
|
|
|
|
named after the driver for this adapter in /proc/scsi. You'll also see a list
|
|
|
|
of all recognized SCSI devices in /proc/scsi:
|
|
|
|
|
|
|
|
>cat /proc/scsi/scsi
|
|
|
|
Attached devices:
|
|
|
|
Host: scsi0 Channel: 00 Id: 00 Lun: 00
|
|
|
|
Vendor: IBM Model: DGHS09U Rev: 03E0
|
|
|
|
Type: Direct-Access ANSI SCSI revision: 03
|
|
|
|
Host: scsi0 Channel: 00 Id: 06 Lun: 00
|
|
|
|
Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
|
|
|
|
Type: CD-ROM ANSI SCSI revision: 02
|
|
|
|
|
|
|
|
|
|
|
|
The directory named after the driver has one file for each adapter found in
|
|
|
|
the system. These files contain information about the controller, including
|
|
|
|
the used IRQ and the IO address range. The amount of information shown is
|
|
|
|
dependent on the adapter you use. The example shows the output for an Adaptec
|
|
|
|
AHA-2940 SCSI adapter:
|
|
|
|
|
|
|
|
> cat /proc/scsi/aic7xxx/0
|
|
|
|
|
|
|
|
Adaptec AIC7xxx driver version: 5.1.19/3.2.4
|
|
|
|
Compile Options:
|
|
|
|
TCQ Enabled By Default : Disabled
|
|
|
|
AIC7XXX_PROC_STATS : Disabled
|
|
|
|
AIC7XXX_RESET_DELAY : 5
|
|
|
|
Adapter Configuration:
|
|
|
|
SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
|
|
|
|
Ultra Wide Controller
|
|
|
|
PCI MMAPed I/O Base: 0xeb001000
|
|
|
|
Adapter SEEPROM Config: SEEPROM found and used.
|
|
|
|
Adaptec SCSI BIOS: Enabled
|
|
|
|
IRQ: 10
|
|
|
|
SCBs: Active 0, Max Active 2,
|
|
|
|
Allocated 15, HW 16, Page 255
|
|
|
|
Interrupts: 160328
|
|
|
|
BIOS Control Word: 0x18b6
|
|
|
|
Adapter Control Word: 0x005b
|
|
|
|
Extended Translation: Enabled
|
|
|
|
Disconnect Enable Flags: 0xffff
|
|
|
|
Ultra Enable Flags: 0x0001
|
|
|
|
Tag Queue Enable Flags: 0x0000
|
|
|
|
Ordered Queue Tag Flags: 0x0000
|
|
|
|
Default Tag Queue Depth: 8
|
|
|
|
Tagged Queue By Device array for aic7xxx host instance 0:
|
|
|
|
{255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
|
|
|
|
Actual queue depth per device for aic7xxx host instance 0:
|
|
|
|
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
|
|
|
|
Statistics:
|
|
|
|
(scsi0:0:0:0)
|
|
|
|
Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
|
|
|
|
Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
|
|
|
|
Total transfers 160151 (74577 reads and 85574 writes)
|
|
|
|
(scsi0:0:6:0)
|
|
|
|
Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
|
|
|
|
Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
|
|
|
|
Total transfers 0 (0 reads and 0 writes)
|
|
|
|
|
|
|
|
|
|
|
|
1.6 Parallel port info in /proc/parport
|
|
|
|
---------------------------------------
|
|
|
|
|
|
|
|
The directory /proc/parport contains information about the parallel ports of
|
|
|
|
your system. It has one subdirectory for each port, named after the port
|
|
|
|
number (0,1,2,...).
|
|
|
|
|
|
|
|
These directories contain the four files shown in Table 1-8.
|
|
|
|
|
|
|
|
|
|
|
|
Table 1-8: Files in /proc/parport
|
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
autoprobe Any IEEE-1284 device ID information that has been acquired.
|
|
|
|
devices list of the device drivers using that port. A + will appear by the
|
|
|
|
name of the device currently using the port (it might not appear
|
|
|
|
against any).
|
|
|
|
hardware Parallel port's base address, IRQ line and DMA channel.
|
|
|
|
irq IRQ that parport is using for that port. This is in a separate
|
|
|
|
file to allow you to alter it by writing a new value in (IRQ
|
|
|
|
number or none).
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
1.7 TTY info in /proc/tty
|
|
|
|
-------------------------
|
|
|
|
|
|
|
|
Information about the available and actually used tty's can be found in the
|
|
|
|
directory /proc/tty.You'll find entries for drivers and line disciplines in
|
|
|
|
this directory, as shown in Table 1-9.
|
|
|
|
|
|
|
|
|
|
|
|
Table 1-9: Files in /proc/tty
|
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
drivers list of drivers and their usage
|
|
|
|
ldiscs registered line disciplines
|
|
|
|
driver/serial usage statistic and status of single tty lines
|
|
|
|
..............................................................................
|
|
|
|
|
|
|
|
To see which tty's are currently in use, you can simply look into the file
|
|
|
|
/proc/tty/drivers:
|
|
|
|
|
|
|
|
> cat /proc/tty/drivers
|
|
|
|
pty_slave /dev/pts 136 0-255 pty:slave
|
|
|
|
pty_master /dev/ptm 128 0-255 pty:master
|
|
|
|
pty_slave /dev/ttyp 3 0-255 pty:slave
|
|
|
|
pty_master /dev/pty 2 0-255 pty:master
|
|
|
|
serial /dev/cua 5 64-67 serial:callout
|
|
|
|
serial /dev/ttyS 4 64-67 serial
|
|
|
|
/dev/tty0 /dev/tty0 4 0 system:vtmaster
|
|
|
|
/dev/ptmx /dev/ptmx 5 2 system
|
|
|
|
/dev/console /dev/console 5 1 system:console
|
|
|
|
/dev/tty /dev/tty 5 0 system:/dev/tty
|
|
|
|
unknown /dev/tty 4 1-63 console
|
|
|
|
|
|
|
|
|
|
|
|
1.8 Miscellaneous kernel statistics in /proc/stat
|
|
|
|
-------------------------------------------------
|
|
|
|
|
|
|
|
Various pieces of information about kernel activity are available in the
|
|
|
|
/proc/stat file. All of the numbers reported in this file are aggregates
|
|
|
|
since the system first booted. For a quick look, simply cat the file:
|
|
|
|
|
|
|
|
> cat /proc/stat
|
2007-10-20 09:03:38 +08:00
|
|
|
cpu 2255 34 2290 22625563 6290 127 456 0
|
|
|
|
cpu0 1132 34 1441 11311718 3675 127 438 0
|
|
|
|
cpu1 1123 0 849 11313845 2614 0 18 0
|
2005-04-17 06:20:36 +08:00
|
|
|
intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
|
|
|
|
ctxt 1990473
|
|
|
|
btime 1062191376
|
|
|
|
processes 2915
|
|
|
|
procs_running 1
|
|
|
|
procs_blocked 0
|
|
|
|
|
|
|
|
The very first "cpu" line aggregates the numbers in all of the other "cpuN"
|
|
|
|
lines. These numbers identify the amount of time the CPU has spent performing
|
|
|
|
different kinds of work. Time units are in USER_HZ (typically hundredths of a
|
|
|
|
second). The meanings of the columns are as follows, from left to right:
|
|
|
|
|
|
|
|
- user: normal processes executing in user mode
|
|
|
|
- nice: niced processes executing in user mode
|
|
|
|
- system: processes executing in kernel mode
|
|
|
|
- idle: twiddling thumbs
|
|
|
|
- iowait: waiting for I/O to complete
|
|
|
|
- irq: servicing interrupts
|
|
|
|
- softirq: servicing softirqs
|
2007-10-20 09:03:38 +08:00
|
|
|
- steal: involuntary wait
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
The "intr" line gives counts of interrupts serviced since boot time, for each
|
|
|
|
of the possible system interrupts. The first column is the total of all
|
|
|
|
interrupts serviced; each subsequent column is the total for that particular
|
|
|
|
interrupt.
|
|
|
|
|
|
|
|
The "ctxt" line gives the total number of context switches across all CPUs.
|
|
|
|
|
|
|
|
The "btime" line gives the time at which the system booted, in seconds since
|
|
|
|
the Unix epoch.
|
|
|
|
|
|
|
|
The "processes" line gives the number of processes and threads created, which
|
|
|
|
includes (but is not limited to) those created by calls to the fork() and
|
|
|
|
clone() system calls.
|
|
|
|
|
|
|
|
The "procs_running" line gives the number of processes currently running on
|
|
|
|
CPUs.
|
|
|
|
|
|
|
|
The "procs_blocked" line gives the number of processes currently blocked,
|
|
|
|
waiting for I/O to complete.
|
|
|
|
|
2008-10-10 11:21:54 +08:00
|
|
|
|
2008-01-29 13:19:52 +08:00
|
|
|
1.9 Ext4 file system parameters
|
|
|
|
------------------------------
|
2008-10-10 11:21:54 +08:00
|
|
|
|
|
|
|
Information about mounted ext4 file systems can be found in
|
|
|
|
/proc/fs/ext4. Each mounted filesystem will have a directory in
|
|
|
|
/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
|
|
|
|
/proc/fs/ext4/dm-0). The files in each per-device directory are shown
|
|
|
|
in Table 1-10, below.
|
|
|
|
|
|
|
|
Table 1-10: Files in /proc/fs/ext4/<devname>
|
|
|
|
..............................................................................
|
|
|
|
File Content
|
|
|
|
mb_groups details of multiblock allocator buddy cache of free blocks
|
|
|
|
mb_history multiblock allocation history
|
|
|
|
..............................................................................
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
Summary
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
The /proc file system serves information about the running system. It not only
|
|
|
|
allows access to process data but also allows you to request the kernel status
|
|
|
|
by reading files in the hierarchy.
|
|
|
|
|
|
|
|
The directory structure of /proc reflects the types of information and makes
|
|
|
|
it easy, if not obvious, where to look for specific data.
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
CHAPTER 2: MODIFYING SYSTEM PARAMETERS
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
In This Chapter
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
* Modifying kernel parameters by writing into files found in /proc/sys
|
|
|
|
* Exploring the files which modify certain parameters
|
|
|
|
* Review of the /proc/sys file tree
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
A very interesting part of /proc is the directory /proc/sys. This is not only
|
|
|
|
a source of information, it also allows you to change parameters within the
|
|
|
|
kernel. Be very careful when attempting this. You can optimize your system,
|
|
|
|
but you can also cause it to crash. Never alter kernel parameters on a
|
|
|
|
production system. Set up a development machine and test to make sure that
|
|
|
|
everything works the way you want it to. You may have no alternative but to
|
|
|
|
reboot the machine once an error has been made.
|
|
|
|
|
|
|
|
To change a value, simply echo the new value into the file. An example is
|
|
|
|
given below in the section on the file system data. You need to be root to do
|
|
|
|
this. You can create your own boot script to perform this every time your
|
|
|
|
system boots.
|
|
|
|
|
|
|
|
The files in /proc/sys can be used to fine tune and monitor miscellaneous and
|
|
|
|
general things in the operation of the Linux kernel. Since some of the files
|
|
|
|
can inadvertently disrupt your system, it is advisable to read both
|
|
|
|
documentation and source before actually making adjustments. In any case, be
|
|
|
|
very careful when writing to any of these files. The entries in /proc may
|
|
|
|
change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
|
|
|
|
review the kernel documentation in the directory /usr/src/linux/Documentation.
|
|
|
|
This chapter is heavily based on the documentation included in the pre 2.2
|
|
|
|
kernels, and became part of it in version 2.2.1 of the Linux kernel.
|
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
Please see: Documentation/sysctls/ directory for descriptions of these
|
2009-01-16 05:50:42 +08:00
|
|
|
entries.
|
2006-01-08 17:00:39 +08:00
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
------------------------------------------------------------------------------
|
|
|
|
Summary
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
Certain aspects of kernel behavior can be modified at runtime, without the
|
|
|
|
need to recompile the kernel, or even to reboot the system. The files in the
|
|
|
|
/proc/sys tree can not only be read, but also modified. You can use the echo
|
|
|
|
command to write value into these files, thereby changing the default settings
|
|
|
|
of the kernel.
|
|
|
|
------------------------------------------------------------------------------
|
2006-01-08 17:00:39 +08:00
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
------------------------------------------------------------------------------
|
|
|
|
CHAPTER 3: PER-PROCESS PARAMETERS
|
|
|
|
------------------------------------------------------------------------------
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
|
2006-09-29 16:59:45 +08:00
|
|
|
------------------------------------------------------
|
|
|
|
|
|
|
|
This file can be used to adjust the score used to select which processes
|
|
|
|
should be killed in an out-of-memory situation. Giving it a high score will
|
|
|
|
increase the likelihood of this process being killed by the oom-killer. Valid
|
|
|
|
values are in the range -16 to +15, plus the special value -17, which disables
|
|
|
|
oom-killing altogether for this process.
|
|
|
|
|
2009-01-30 06:25:09 +08:00
|
|
|
The process to be killed in an out-of-memory situation is selected among all others
|
|
|
|
based on its badness score. This value equals the original memory size of the process
|
|
|
|
and is then updated according to its CPU time (utime + stime) and the
|
|
|
|
run time (uptime - start time). The longer it runs the smaller is the score.
|
|
|
|
Badness score is divided by the square root of the CPU time and then by
|
|
|
|
the double square root of the run time.
|
|
|
|
|
|
|
|
Swapped out tasks are killed first. Half of each child's memory size is added to
|
|
|
|
the parent's score if they do not share the same memory. Thus forking servers
|
|
|
|
are the prime candidates to be killed. Having only one 'hungry' child will make
|
|
|
|
parent less preferable than the child.
|
|
|
|
|
|
|
|
/proc/<pid>/oom_score shows process' current badness score.
|
|
|
|
|
|
|
|
The following heuristics are then applied:
|
|
|
|
* if the task was reniced, its score doubles
|
|
|
|
* superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE
|
|
|
|
or CAP_SYS_RAWIO) have their score divided by 4
|
|
|
|
* if oom condition happened in one cpuset and checked task does not belong
|
|
|
|
to it, its score is divided by 8
|
|
|
|
* the resulting score is multiplied by two to the power of oom_adj, i.e.
|
|
|
|
points <<= oom_adj when it is positive and
|
|
|
|
points >>= -(oom_adj) otherwise
|
|
|
|
|
|
|
|
The task with the highest badness score is then selected and its children
|
|
|
|
are killed, process itself will be killed in an OOM situation when it does
|
|
|
|
not have children or some of them disabled oom like described above.
|
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
3.2 /proc/<pid>/oom_score - Display current oom-killer score
|
2006-09-29 16:59:45 +08:00
|
|
|
-------------------------------------------------------------
|
|
|
|
|
|
|
|
This file can be used to check the current score used by the oom-killer is for
|
|
|
|
any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
|
|
|
|
process should be killed in an out-of-memory situation.
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2007-03-05 16:30:54 +08:00
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
3.3 /proc/<pid>/io - Display the IO accounting fields
|
2007-03-05 16:30:54 +08:00
|
|
|
-------------------------------------------------------
|
|
|
|
|
|
|
|
This file contains IO statistics for each running process
|
|
|
|
|
|
|
|
Example
|
|
|
|
-------
|
|
|
|
|
|
|
|
test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
|
|
|
|
[1] 3828
|
|
|
|
|
|
|
|
test:/tmp # cat /proc/3828/io
|
|
|
|
rchar: 323934931
|
|
|
|
wchar: 323929600
|
|
|
|
syscr: 632687
|
|
|
|
syscw: 632675
|
|
|
|
read_bytes: 0
|
|
|
|
write_bytes: 323932160
|
|
|
|
cancelled_write_bytes: 0
|
|
|
|
|
|
|
|
|
|
|
|
Description
|
|
|
|
-----------
|
|
|
|
|
|
|
|
rchar
|
|
|
|
-----
|
|
|
|
|
|
|
|
I/O counter: chars read
|
|
|
|
The number of bytes which this task has caused to be read from storage. This
|
|
|
|
is simply the sum of bytes which this process passed to read() and pread().
|
|
|
|
It includes things like tty IO and it is unaffected by whether or not actual
|
|
|
|
physical disk IO was required (the read might have been satisfied from
|
|
|
|
pagecache)
|
|
|
|
|
|
|
|
|
|
|
|
wchar
|
|
|
|
-----
|
|
|
|
|
|
|
|
I/O counter: chars written
|
|
|
|
The number of bytes which this task has caused, or shall cause to be written
|
|
|
|
to disk. Similar caveats apply here as with rchar.
|
|
|
|
|
|
|
|
|
|
|
|
syscr
|
|
|
|
-----
|
|
|
|
|
|
|
|
I/O counter: read syscalls
|
|
|
|
Attempt to count the number of read I/O operations, i.e. syscalls like read()
|
|
|
|
and pread().
|
|
|
|
|
|
|
|
|
|
|
|
syscw
|
|
|
|
-----
|
|
|
|
|
|
|
|
I/O counter: write syscalls
|
|
|
|
Attempt to count the number of write I/O operations, i.e. syscalls like
|
|
|
|
write() and pwrite().
|
|
|
|
|
|
|
|
|
|
|
|
read_bytes
|
|
|
|
----------
|
|
|
|
|
|
|
|
I/O counter: bytes read
|
|
|
|
Attempt to count the number of bytes which this process really did cause to
|
|
|
|
be fetched from the storage layer. Done at the submit_bio() level, so it is
|
|
|
|
accurate for block-backed filesystems. <please add status regarding NFS and
|
|
|
|
CIFS at a later time>
|
|
|
|
|
|
|
|
|
|
|
|
write_bytes
|
|
|
|
-----------
|
|
|
|
|
|
|
|
I/O counter: bytes written
|
|
|
|
Attempt to count the number of bytes which this process caused to be sent to
|
|
|
|
the storage layer. This is done at page-dirtying time.
|
|
|
|
|
|
|
|
|
|
|
|
cancelled_write_bytes
|
|
|
|
---------------------
|
|
|
|
|
|
|
|
The big inaccuracy here is truncate. If a process writes 1MB to a file and
|
|
|
|
then deletes the file, it will in fact perform no writeout. But it will have
|
|
|
|
been accounted as having caused 1MB of write.
|
|
|
|
In other words: The number of bytes which this process caused to not happen,
|
|
|
|
by truncating pagecache. A task can cause "negative" IO too. If this task
|
|
|
|
truncates some dirty pagecache, some IO which another task has been accounted
|
|
|
|
for (in it's write_bytes) will not be happening. We _could_ just subtract that
|
|
|
|
from the truncating task's write_bytes, but there is information loss in doing
|
|
|
|
that.
|
|
|
|
|
|
|
|
|
|
|
|
Note
|
|
|
|
----
|
|
|
|
|
|
|
|
At its current implementation state, this is a bit racy on 32-bit machines: if
|
|
|
|
process A reads process B's /proc/pid/io while process B is updating one of
|
|
|
|
those 64-bit counters, process A could see an intermediate result.
|
|
|
|
|
|
|
|
|
|
|
|
More information about this can be found within the taskstats documentation in
|
|
|
|
Documentation/accounting.
|
|
|
|
|
2009-04-03 07:57:20 +08:00
|
|
|
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
|
2007-07-19 16:48:31 +08:00
|
|
|
---------------------------------------------------------------
|
|
|
|
When a process is dumped, all anonymous memory is written to a core file as
|
|
|
|
long as the size of the core file isn't limited. But sometimes we don't want
|
|
|
|
to dump some memory segments, for example, huge shared memory. Conversely,
|
|
|
|
sometimes we want to save file-backed memory segments into a core file, not
|
|
|
|
only the individual files.
|
|
|
|
|
|
|
|
/proc/<pid>/coredump_filter allows you to customize which memory segments
|
|
|
|
will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
|
|
|
|
of memory types. If a bit of the bitmask is set, memory segments of the
|
|
|
|
corresponding memory type are dumped, otherwise they are not dumped.
|
|
|
|
|
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 11:27:08 +08:00
|
|
|
The following 7 memory types are supported:
|
2007-07-19 16:48:31 +08:00
|
|
|
- (bit 0) anonymous private memory
|
|
|
|
- (bit 1) anonymous shared memory
|
|
|
|
- (bit 2) file-backed private memory
|
|
|
|
- (bit 3) file-backed shared memory
|
2008-09-13 17:33:10 +08:00
|
|
|
- (bit 4) ELF header pages in file-backed private memory areas (it is
|
|
|
|
effective only if the bit 2 is cleared)
|
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 11:27:08 +08:00
|
|
|
- (bit 5) hugetlb private memory
|
|
|
|
- (bit 6) hugetlb shared memory
|
2007-07-19 16:48:31 +08:00
|
|
|
|
|
|
|
Note that MMIO pages such as frame buffer are never dumped and vDSO pages
|
|
|
|
are always dumped regardless of the bitmask status.
|
|
|
|
|
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 11:27:08 +08:00
|
|
|
Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
|
|
|
|
effected by bit 5-6.
|
|
|
|
|
|
|
|
Default value of coredump_filter is 0x23; this means all anonymous memory
|
|
|
|
segments and hugetlb private memory are dumped.
|
2007-07-19 16:48:31 +08:00
|
|
|
|
|
|
|
If you don't want to dump all shared memory segments attached to pid 1234,
|
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 11:27:08 +08:00
|
|
|
write 0x21 to the process's proc file.
|
2007-07-19 16:48:31 +08:00
|
|
|
|
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 11:27:08 +08:00
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$ echo 0x21 > /proc/1234/coredump_filter
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2007-07-19 16:48:31 +08:00
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When a new process is created, the process inherits the bitmask status from its
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parent. It is useful to set up coredump_filter before the program runs.
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For example:
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$ echo 0x7 > /proc/self/coredump_filter
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$ ./some_program
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2009-04-03 07:57:20 +08:00
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3.5 /proc/<pid>/mountinfo - Information about mounts
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2008-03-27 20:06:25 +08:00
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--------------------------------------------------------
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This file contains lines of the form:
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36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
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(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
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(1) mount ID: unique identifier of the mount (may be reused after umount)
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(2) parent ID: ID of parent (or of self for the top of the mount tree)
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(3) major:minor: value of st_dev for files on filesystem
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(4) root: root of the mount within the filesystem
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(5) mount point: mount point relative to the process's root
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(6) mount options: per mount options
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(7) optional fields: zero or more fields of the form "tag[:value]"
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(8) separator: marks the end of the optional fields
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(9) filesystem type: name of filesystem of the form "type[.subtype]"
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(10) mount source: filesystem specific information or "none"
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(11) super options: per super block options
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Parsers should ignore all unrecognised optional fields. Currently the
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possible optional fields are:
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shared:X mount is shared in peer group X
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master:X mount is slave to peer group X
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2008-03-27 20:06:26 +08:00
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propagate_from:X mount is slave and receives propagation from peer group X (*)
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2008-03-27 20:06:25 +08:00
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unbindable mount is unbindable
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2008-03-27 20:06:26 +08:00
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(*) X is the closest dominant peer group under the process's root. If
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X is the immediate master of the mount, or if there's no dominant peer
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group under the same root, then only the "master:X" field is present
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and not the "propagate_from:X" field.
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2008-03-27 20:06:25 +08:00
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For more information on mount propagation see:
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Documentation/filesystems/sharedsubtree.txt
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