On 11/7/19 12:17 PM, Tejun Heo wrote:
> Hello,
>
> v2: Build fix when !DEBUG.
>
> 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-relocate-bfqg_-rwstat-helpers.patch
> 0002-bfq-iosched-stop-using-blkg-stat_bytes-and-stat_ios.patch
> 0003-blk-throtl-stop-using-blkg-stat_bytes-and-stat_ios.patch
> 0004-blk-cgroup-remove-now-unused-blkg_print_stat_-bytes-.patch
> 0005-blk-cgroup-reimplement-basic-IO-stats-using-cgroup-r.patch
> 0006-blk-cgroup-separate-out-blkg_rwstat-under-CONFIG_BLK.patch
>
> 0001-0003 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.
> 0004 is a follow-up cleanup.
>
> 0005 switches blk-cgroup to cgroup rstat.
>
> 0006 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
>
> block/for-next 40afbe18b03a ("Merge branch 'for-5.5/drivers-post' into for-next")
> + block/for-linus b0814361a25c ("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, applied!
--
Jens Axboe
