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OpenCloudOS-Kernel/Documentation/block/stat.rst

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docs: block: convert to ReST Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 06:45:00 +08:00
===============================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
Block layer statistics in /sys/block/<dev>/stat
===============================================
This file documents the contents of the /sys/block/<dev>/stat file.
The stat file provides several statistics about the state of block
device <dev>.
docs: block: convert to ReST Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 06:45:00 +08:00
Q.
Why are there multiple statistics in a single file? Doesn't sysfs
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
normally contain a single value per file?
docs: block: convert to ReST Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 06:45:00 +08:00
A.
By having a single file, the kernel can guarantee that the statistics
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
represent a consistent snapshot of the state of the device. If the
statistics were exported as multiple files containing one statistic
each, it would be impossible to guarantee that a set of readings
represent a single point in time.
The stat file consists of a single line of text containing 11 decimal
values separated by whitespace. The fields are summarized in the
following table, and described in more detail below.
docs: block: convert to ReST Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 06:45:00 +08:00
=============== ============= =================================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
Name units description
docs: block: convert to ReST Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 06:45:00 +08:00
=============== ============= =================================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
read I/Os requests number of read I/Os processed
read merges requests number of read I/Os merged with in-queue I/O
read sectors sectors number of sectors read
read ticks milliseconds total wait time for read requests
write I/Os requests number of write I/Os processed
write merges requests number of write I/Os merged with in-queue I/O
write sectors sectors number of sectors written
write ticks milliseconds total wait time for write requests
in_flight requests number of I/Os currently in flight
io_ticks milliseconds total time this block device has been active
time_in_queue milliseconds total wait time for all requests
block: Track DISCARD statistics and output them in stat and diskstat Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-18 19:47:40 +08:00
discard I/Os requests number of discard I/Os processed
discard merges requests number of discard I/Os merged with in-queue I/O
discard sectors sectors number of sectors discarded
discard ticks milliseconds total wait time for discard requests
block: add iostat counters for flush requests Requests that triggers flushing volatile writeback cache to disk (barriers) have significant effect to overall performance. Block layer has sophisticated engine for combining several flush requests into one. But there is no statistics for actual flushes executed by disk. Requests which trigger flushes usually are barriers - zero-size writes. This patch adds two iostat counters into /sys/class/block/$dev/stat and /proc/diskstats - count of completed flush requests and their total time. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-21 18:40:26 +08:00
flush I/Os requests number of flush I/Os processed
flush ticks milliseconds total wait time for flush requests
docs: block: convert to ReST Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 06:45:00 +08:00
=============== ============= =================================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
block: Track DISCARD statistics and output them in stat and diskstat Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-18 19:47:40 +08:00
read I/Os, write I/Os, discard I/0s
===================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
These values increment when an I/O request completes.
block: add iostat counters for flush requests Requests that triggers flushing volatile writeback cache to disk (barriers) have significant effect to overall performance. Block layer has sophisticated engine for combining several flush requests into one. But there is no statistics for actual flushes executed by disk. Requests which trigger flushes usually are barriers - zero-size writes. This patch adds two iostat counters into /sys/class/block/$dev/stat and /proc/diskstats - count of completed flush requests and their total time. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-21 18:40:26 +08:00
flush I/Os
==========
These values increment when an flush I/O request completes.
Block layer combines flush requests and executes at most one at a time.
This counts flush requests executed by disk. Not tracked for partitions.
block: Track DISCARD statistics and output them in stat and diskstat Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-18 19:47:40 +08:00
read merges, write merges, discard merges
=========================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
These values increment when an I/O request is merged with an
already-queued I/O request.
block: Track DISCARD statistics and output them in stat and diskstat Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-18 19:47:40 +08:00
read sectors, write sectors, discard_sectors
============================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
block: Track DISCARD statistics and output them in stat and diskstat Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-18 19:47:40 +08:00
These values count the number of sectors read from, written to, or
discarded from this block device. The "sectors" in question are the
standard UNIX 512-byte sectors, not any device- or filesystem-specific
block size. The counters are incremented when the I/O completes.
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
block: add iostat counters for flush requests Requests that triggers flushing volatile writeback cache to disk (barriers) have significant effect to overall performance. Block layer has sophisticated engine for combining several flush requests into one. But there is no statistics for actual flushes executed by disk. Requests which trigger flushes usually are barriers - zero-size writes. This patch adds two iostat counters into /sys/class/block/$dev/stat and /proc/diskstats - count of completed flush requests and their total time. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-21 18:40:26 +08:00
read ticks, write ticks, discard ticks, flush ticks
===================================================
[PATCH] block/stat.txt I couldn't find any docs explaining the contents of /sys/block/<dev>/stat, so I wrote up the following. I'm not completely sure it's accurate - Jens, could you give a yea or nay on this? In particular, the counts of read/write IOs and read/write sectors are incremented in different places - it looks like they both increment as the request is being finished, but I'm not completely sure of that. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 17:04:00 +08:00
These values count the number of milliseconds that I/O requests have
waited on this block device. If there are multiple I/O requests waiting,
these values will increase at a rate greater than 1000/second; for
example, if 60 read requests wait for an average of 30 ms, the read_ticks
field will increase by 60*30 = 1800.
in_flight
=========
This value counts the number of I/O requests that have been issued to
the device driver but have not yet completed. It does not include I/O
requests that are in the queue but not yet issued to the device driver.
io_ticks
========
This value counts the number of milliseconds during which the device has
had I/O requests queued.
time_in_queue
=============
This value counts the number of milliseconds that I/O requests have waited
on this block device. If there are multiple I/O requests waiting, this
value will increase as the product of the number of milliseconds times the
number of requests waiting (see "read ticks" above for an example).