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authorMichael Callahan <michaelcallahan@fb.com>2018-07-18 14:47:40 +0300
committerJens Axboe <axboe@kernel.dk>2018-07-18 17:44:22 +0300
commitbdca3c87fb7ad1cc61d231d37eb0d8f90d001e0c (patch)
treea5890cef3e0fb586f2a2b2a366423e71af96d821 /Documentation/iostats.txt
parentddcf35d397976421a4ec1d0d00fbcc027a8cb034 (diff)
downloadlinux-bdca3c87fb7ad1cc61d231d37eb0d8f90d001e0c.tar.xz
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>
Diffstat (limited to 'Documentation/iostats.txt')
-rw-r--r--Documentation/iostats.txt15
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/iostats.txt b/Documentation/iostats.txt
index 04d394a2e06c..49df45f90e8a 100644
--- a/Documentation/iostats.txt
+++ b/Documentation/iostats.txt
@@ -31,6 +31,9 @@ Here are examples of these different formats::
3 0 hda 446216 784926 9550688 4382310 424847 312726 5922052 19310380 0 3376340 23705160
3 1 hda1 35486 38030 38030 38030
+ 4.18+ diskstats:
+ 3 0 hda 446216 784926 9550688 4382310 424847 312726 5922052 19310380 0 3376340 23705160 0 0 0 0
+
On 2.4 you might execute ``grep 'hda ' /proc/partitions``. On 2.6+, you have
a choice of ``cat /sys/block/hda/stat`` or ``grep 'hda ' /proc/diskstats``.
@@ -101,6 +104,18 @@ Field 11 -- weighted # of milliseconds spent doing I/Os
last update of this field. This can provide an easy measure of both
I/O completion time and the backlog that may be accumulating.
+Field 12 -- # of discards completed
+ This is the total number of discards completed successfully.
+
+Field 13 -- # of discards merged
+ See the description of field 2
+
+Field 14 -- # of sectors discarded
+ This is the total number of sectors discarded successfully.
+
+Field 15 -- # of milliseconds spent discarding
+ This is the total number of milliseconds spent by all discards (as
+ measured from __make_request() to end_that_request_last()).
To avoid introducing performance bottlenecks, no locks are held while
modifying these counters. This implies that minor inaccuracies may be