Re: [PATCH v2 0/3] block: skip the blkcg walk in blk_cgroup_congested() when nothing is throttled

On Fri, 14 Aug 2026 09:56:36 -0700, Usama Arif wrote:
> blk_cgroup_congested() walks the current task's blkcg ancestor chain on every
> readahead decision and, once swap is in use, on every anonymous and shmem
> folio allocation.  The answer is almost always "no", but finding that out
> costs two loads per level on two cold cache lines, plus an out-of-line
> kthread_blkcg() and an RCU read-side pair.  On a fleet profile of hosts
> running containers with 5-10 level hierarchies it costs about as much as all
> of mutex_lock(), 99.4% of it under __folio_throttle_swaprate().
> 
> [...]

Applied, thanks!

[1/3] blk-iolatency: clear delay state when freeing policy data
      commit: 8935bf22c0a0db517a7f72f7097300e05dd852f5
[2/3] blk-iocost: clear delay state when freeing policy data
      commit: 97cb95d2148835ae86ff916b145aef332d40439d
[3/3] block: skip blkcg walk in blk_cgroup_congested() when nothing throttled
      commit: 4febfe7d98948bf6693f5c6a0a7e198e8fb4e584

Best regards,
-- 
Jens Axboe