This patchset was originally posted by Michael Callahan. https://marc.info/?l=linux-block&m=146541910129172&w=2 The patchset is refreshed on top of the current git master v4.17-1306-g716a685 and a patch was added to add discard stats for cgroup io.stat. The original patchset description from Michael follows. This patch set separates block layer statistics for discards from writes. Discards are currently bundled with writes in the various /sys/block/*/stat files as well as in /proc/diskstats. However discards are nearly always used to mark storage that is no longer in use. There are many reasons having discard not counted with writes is useful: 1) For many non volatile memory devices it is just nice to know that discards are enabled and working properly. 2) Discards have different performance characteristics than writes. They are generally much faster and larger and bundling them makes performance statistics less meaningful. 3) Discards are not writes in terms of tracking device lifetime. If a device supports six device writes per day it is nice to know how many writes have actually been written to the device as discards do not count against that total. Separation of discard statistics is accomplished by expanding the struct diskstat arrays to 3 entries for STAT_READ, STAT_WRITE, and STAT_DISCARD. A new rw_stat_group function is then used to convert from rw_flags (cmd_flags from requests, bi_rw from bios) into the appropriate stat group which is then tracked as before. Lastly the new statistics are appended to the current /sys/bloc/*/stat and /proc/diskstats on output such that they are the last four entries of each. These are analogous to the four read and write statistics. * Number of discard ios completed * Number of discard ios merged * Number of discard sectors completed * Milliseconds spent on discard requests. [before ~]# cat sys/block/nvme0/stat 296550701 0 2372405688 67317193 19672752 0 7972237312 9375167 0 2787238 79718726 [after ~]# cat sys/block/nvme0/stat 296550701 0 2372405688 67317193 18034352 0 4616794112 9125902 0 2787238 79718726 1638400 0 3355443200 249265 Note that the discards have moved out of the write fields to the end and that the write fields are now smaller by the difference. Adding the new statistics to the end of /sys/block/*/stat and /proc/diskstats is backwards compatible with both iostat and vmstat which pick up just the old fields: [root@after ~]# iostat -x Linux 4.5.0_68319_ge5065f4-dirty (##hostname###) 05/17/2016 _x86_64_ (48 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.41 0.00 0.23 0.01 0.00 99.35 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.01 7.50 0.20 3.61 16.65 708.41 190.03 0.09 22.53 1.16 0.44 nvme0n1 0.00 0.00 587.03 35.70 4696.25 9139.08 22.22 0.16 0.24 0.01 0.55 [root@after ~]# vmstat -d disk- ------------reads------------ ------------writes----------- -----IO------ total merged sectors ms total merged sectors ms cur sec ram0 0 0 0 0 0 0 0 0 0 0 ram1 0 0 0 0 0 0 0 0 0 0 ram2 0 0 0 0 0 0 0 0 0 0 ram3 0 0 0 0 0 0 0 0 0 0 ram4 0 0 0 0 0 0 0 0 0 0 ram5 0 0 0 0 0 0 0 0 0 0 ram6 0 0 0 0 0 0 0 0 0 0 ram7 0 0 0 0 0 0 0 0 0 0 ram8 0 0 0 0 0 0 0 0 0 0 ram9 0 0 0 0 0 0 0 0 0 0 ram10 0 0 0 0 0 0 0 0 0 0 ram11 0 0 0 0 0 0 0 0 0 0 ram12 0 0 0 0 0 0 0 0 0 0 ram13 0 0 0 0 0 0 0 0 0 0 ram14 0 0 0 0 0 0 0 0 0 0 ram15 0 0 0 0 0 0 0 0 0 0 sda 102903 5247 8408420 47424 1820306 3782041 357153613 43320121 0 2228 nvme0n1 145633279 0 1165066312 18981333 13107200 0 3355443200 6663655 0 1796 loop0 0 0 0 0 0 0 0 0 0 0 loop1 0 0 0 0 0 0 0 0 0 0 [chop rest of loop devices] [root@after ~]# cat /sys/fs/cgroup/user.slice/io.stat 8:0 rbytes=3534848 wbytes=4096 rios=723 wios=1 dbytes=20592091136 dios=16189 This patchset contains the following six patches. 0001-block-make-bdev_ops-rw_page-take-a-REQ_OP-instead-of.patch 0002-block-Add-part_stat_read_accum-to-read-across-field-.patch 0003-block-Define-and-use-STAT_READ-and-STAT_WRITE.patch 0004-block-Add-and-use-op_stat_group-for-indexing-disk_st.patch 0005-block-Track-DISCARD-statistics-and-output-them-in-st.patch 0006-blkcg-Track-DISCARD-statistics-and-output-them-in-cg.patch and also available in the following git branch. git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git block-discard-stat diffstat follows. Thanks. Documentation/ABI/testing/procfs-diskstats | 10 ++++++++++ Documentation/admin-guide/cgroup-v2.rst | 10 ++++++---- Documentation/block/stat.txt | 28 ++++++++++++++++------------ Documentation/iostats.txt | 15 +++++++++++++++ block/bio.c | 16 +++++++++------- block/blk-cgroup.c | 14 ++++++++++---- block/blk-core.c | 12 ++++++------ block/genhd.c | 29 ++++++++++++++++++----------- block/partition-generic.c | 25 +++++++++++++++---------- drivers/block/brd.c | 14 +++++++------- drivers/block/drbd/drbd_receiver.c | 3 +-- drivers/block/drbd/drbd_req.c | 4 ++-- drivers/block/drbd/drbd_worker.c | 4 +--- drivers/block/rsxx/dev.c | 6 +++--- drivers/block/zram/zram_drv.c | 19 +++++++++---------- drivers/lightnvm/pblk-cache.c | 5 +++-- drivers/lightnvm/pblk-read.c | 5 +++-- drivers/md/bcache/request.c | 13 +++++-------- drivers/md/dm.c | 6 ++++-- drivers/md/md.c | 8 ++++---- drivers/nvdimm/btt.c | 12 ++++++------ drivers/nvdimm/nd.h | 7 +++---- drivers/nvdimm/pmem.c | 13 ++++++------- fs/block_dev.c | 6 ++++-- fs/ext4/super.c | 5 +++-- fs/ext4/sysfs.c | 6 ++++-- fs/f2fs/f2fs.h | 2 +- fs/f2fs/super.c | 3 ++- fs/mpage.c | 4 ++-- include/linux/bio.h | 4 ++-- include/linux/blk-cgroup.h | 5 ++++- include/linux/blk_types.h | 20 ++++++++++++++++++++ include/linux/blkdev.h | 2 +- include/linux/genhd.h | 14 ++++++++++---- 34 files changed, 215 insertions(+), 134 deletions(-) -- tejun
