abs_vdebt is an atomic_64 which tracks how much over budget a given cgroup
is and controls the activation of use_delay mechanism. Once a cgroup goes
over budget from forced IOs, it has to pay it back with its future budget.
The progress guarantee on debt paying comes from the iocg being active -
active iocgs are processed by the periodic timer, which ensures that as time
passes the debts dissipate and the iocg returns to normal operation.
However, both iocg activation and vdebt handling are asynchronous and a
sequence like the following may happen.
1. The iocg is in the process of being deactivated by the periodic timer.
2. A bio enters ioc_rqos_throttle(), calls iocg_activate() which returns
without anything because it still sees that the iocg is already active.
3. The iocg is deactivated.
4. The bio from #2 is over budget but needs to be forced. It increases
abs_vdebt and goes over the threshold and enables use_delay.
5. IO control is enabled for the iocg's subtree and now IOs are attributed
to the descendant cgroups and the iocg itself no longer issues IOs.
This leaves the iocg with stuck abs_vdebt - it has debt but inactive and no
further IOs which can activate it. This can end up unduly punishing all the
descendants cgroups.
The usual throttling path has the same issue - the iocg must be active while
throttled to ensure that future event will wake it up - and solves the
problem by synchronizing the throttling path with a spinlock. abs_vdebt
handling is another form of overage handling and shares a lot of
characteristics including the fact that it isn't in the hottest path.
This patch fixes the above and other possible races by strictly
synchronizing abs_vdebt and use_delay handling with iocg->waitq.lock.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Vlad Dmitriev <vvd@fb.com>
Cc: stable@vger.kernel.org # v5.4+
Fixes: e1518f63f2 ("blk-iocost: Don't let merges push vtime into the future")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
iocost_monitor.py broke with recent versions of drgn due to helper
being stricter about types. Fix it so that it uses the correct type.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Omar Sandoval <osandov@fb.com>
When outputting json:
* Don't truncate numbers.
* Report address of iocg to ease drilling down further.
When outputting table:
* Use math.ceil() for delay_ms so that small delays don't read as 0.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Json has limited accuracy for numbers and can silently truncate 64bit
values, which can be extremely confusing. Let's consistently use
string encapsulated values for json output.
While at it, convert an unnecesary f-string to str().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a script which can be used to generate device-specific iocost
linear model coefficients.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently a number of Makefiles break when used with toolchains that
pass extra flags in CC and other cross-compile related variables (such
as --sysroot).
Thus we get this error when we use a toolchain that puts --sysroot in
the CC var:
~/src/linux/tools$ make iio
[snip]
iio_event_monitor.c:18:10: fatal error: unistd.h: No such file or directory
#include <unistd.h>
^~~~~~~~~~
This occurs because we clobber several env vars related to
cross-compiling with lines like this:
CC = $(CROSS_COMPILE)gcc
Although this will point to a valid cross-compiler, we lose any extra
flags that might exist in the CC variable, which can break toolchains
that rely on them (for example, those that use --sysroot).
This easily shows up using a Yocto SDK:
$ . [snip]/sdk/environment-setup-cortexa8hf-neon-poky-linux-gnueabi
$ echo $CC
arm-poky-linux-gnueabi-gcc -march=armv7-a -mfpu=neon -mfloat-abi=hard
-mcpu=cortex-a8
--sysroot=[snip]/sdk/sysroots/cortexa8hf-neon-poky-linux-gnueabi
$ echo $CROSS_COMPILE
arm-poky-linux-gnueabi-
$ echo ${CROSS_COMPILE}gcc
krm-poky-linux-gnueabi-gcc
Although arm-poky-linux-gnueabi-gcc is a cross-compiler, we've lost the
--sysroot and other flags that enable us to find the right libraries to
link against, so we can't find unistd.h and other libraries and headers.
Normally with the --sysroot flag we would find unistd.h in the sdk
directory in the sysroot:
$ find [snip]/sdk/sysroots -path '*/usr/include/unistd.h'
[snip]/sdk/sysroots/cortexa8hf-neon-poky-linux-gnueabi/usr/include/unistd.h
The perf Makefile adds CC = $(CROSS_COMPILE)gcc if and only if CC is not
already set, and it compiles correctly with the above toolchain.
So, generalize the logic that perf uses in the common Makefile and
remove the manual CC = $(CROSS_COMPILE)gcc lines from each Makefile.
Note that this patch does not fix cross-compile for all the tools (some
have other bugs), but it does fix it for all except usb and acpi, which
still have other unrelated issues.
I tested both with and without the patch on native and cross-build and
there appear to be no regressions.
Link: http://lkml.kernel.org/r/20180107214028.23771-1-martin@martingkelly.com
Signed-off-by: Martin Kelly <martin@martingkelly.com>
Acked-by: Mark Brown <broonie@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Pali Rohar <pali.rohar@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Valentina Manea <valentina.manea.m@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The error handling in cgroup_event_listener.c did not correctly deal
with either an error opening either <control_file> or
cgroup.event_control. Due to an uninitialized variable the program
exit code was undefined if either of these opens failed.
This patch simplifies and corrects cgroup_event_listener.c error
handling by:
1. using err*() rather than printf(),exit()
2. depending on process exit to close open files
With this patch failures always return non-zero error.
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move the cgroup_event_listener.c tool from Documentation into the new
tools/cgroup directory.
This change involves wiring cgroup_event_listener.c into the tools/
make system so that is can be built with:
$ make tools/cgroup
Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo