Hello,
blk-cgroup IO stats currently use blkg_rwstat which unforutnately
requires walking all descendants recursively on read. On systems with
a large number of cgroups (dead or alive), this can make each stat
read a substantially expensive operation.
This patch updates blk-cgroup to use cgroup rstat which makes stat
reading O(# descendants which have been active since last reading)
instead of O(# descendants).
0001-bfq-iosched-stop-using-blkg-stat_bytes-and-stat_ios.patch
0002-blk-throtl-stop-using-blkg-stat_bytes-and-stat_ios.patch
0003-blk-cgroup-remove-now-unused-blkg_print_stat_-bytes-.patch
0004-blk-cgroup-reimplement-basic-IO-stats-using-cgroup-r.patch
0005-blk-cgroup-separate-out-blkg_rwstat-under-CONFIG_BLK.patch
0001-0002 make bfq-iosched and blk-throtl use their own blkg_rwstat to
track basic IO stats on cgroup1 instead of sharing blk-cgroup core's.
0003 is a follow-up cleanup.
0004 switches blk-cgroup to cgroup rstat.
0005 moves blkg_rwstat to its own files and gate it under a config
option as it's now only used by blk-throtl and bfq-iosched.
The patchset is on top of
for-next/block 257855f86aa2 ("Merge branch 'for-5.4/block' into for-next")
+ [1] blkcg: make blkcg_print_stat() print stats only for online blkgs
and also available in the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-blkcg-rstat
Thanks.
block/Kconfig | 4
block/Kconfig.iosched | 1
block/Makefile | 1
block/bfq-cgroup.c | 37 +++--
block/bfq-iosched.c | 4
block/bfq-iosched.h | 6
block/blk-cgroup-rwstat.c | 129 +++++++++++++++++++
block/blk-cgroup-rwstat.h | 149 ++++++++++++++++++++++
block/blk-cgroup.c | 304 ++++++++++++++-------------------------------
block/blk-throttle.c | 71 +++++++++-
include/linux/blk-cgroup.h | 198 +++++------------------------
11 files changed, 517 insertions(+), 387 deletions(-)
--
tejun
[1] http://lkml.kernel.org/r/20191105160951.GS3622521@xxxxxxxxxxxxxxxxxxxxxxxxxxx
