github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-11-10 08:53:02 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

block: drop the cached plug time when blk_add_rq_to_plug() flushes

Browse Source 
blk_time_get_ns() caches the current time in the task's plug. The idea
is that the cache lives for one plug and is dropped when the plug is
flushed. __blk_flush_plug() and finish_task_switch() do that.

blk_add_rq_to_plug() also flushes, when the plug has too many requests
or the last request is at least BLK_PLUG_FLUSH_SIZE. But it calls
blk_mq_flush_plug_list() directly and never drops the cached time. So
a task that keeps submitting without sleeping stamps every request
after that with the time first cached in the plug. start_time_ns and
io_start_time_ns are stale and the disk stats charge each request for
the whole time since the plug began.

Drop the cached time after the flush, same as __blk_flush_plug() does.

Fixes: da4c8c3d09 ("block: cache current nsec time in struct blk_plug")
Cc: stable@vger.kernel.org
Signed-off-by: Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>
Link: https://patch.msgid.link/20260930-blk-plug-ts-flush-v1-1-bf8ca7bc5cd6@virtuozzo.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Vasileios Almpanis 2026-09-30 14:32:26 +00:00 committed by Jens Axboe
parent 812485c8ff
commit e0f2224433
1 changed files with 1 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
block/blk-mq.c
View File

@ -1384,6 +1384,7 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
(!blk_queue_nomerges(rq->q) &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_mq_flush_plug_list(plug, false);
blk_plug_invalidate_ts();
last = NULL;
trace_block_plug(rq->q);
}