Messages in this thread | | | From | Dexuan Cui <> | Subject | RE: Random high CPU utilization in blk-mq with the none scheduler | Date | Sat, 11 Dec 2021 07:09:45 +0000 |
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> From: Dexuan Cui > Sent: Friday, December 10, 2021 7:45 PM > > > From: Jens Axboe <axboe@kernel.dk> > > > > Just out of curiosity, can you do: > > > > # perf record -a -g -- sleep 3 > > > > when you see the excessive CPU usage, then attach the output of > > > > # perf report -g > > > > to a reply?
I realized you only asked for the output of "pref report -g", which is much smaller. Please see the attachment for it. try_to_grab_pending() is the hottest function, e.g. see line 2479.
It's generated using v5.16-rc4 with the 3 commits reverted: b22809092c70 ("block: replace always false argument with 'false'") ff1552232b36 ("blk-mq: don't issue request directly in case that current is to be blocked") dc5fc361d891 ("block: attempt direct issue of plug list")
> > How confident are you in your bisect result? > > > > Jens Axboe
I did some tests again and I'm pretty confident that the commit b22809092c70 resolves the excessive CPU usage.
Thanks, Dexuan [unhandled content-type:application/octet-stream] | |