From: Dexuan Cui <decui@microsoft.com>
To: Jens Axboe <axboe@kernel.dk>,
"'ming.lei@redhat.com'" <ming.lei@redhat.com>,
'Christoph Hellwig' <hch@lst.de>,
"'linux-block@vger.kernel.org'" <linux-block@vger.kernel.org>
Cc: Long Li <longli@microsoft.com>,
"Michael Kelley (LINUX)" <mikelley@microsoft.com>,
"'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: RE: Random high CPU utilization in blk-mq with the none scheduler
Date: Sat, 11 Dec 2021 07:09:45 +0000 [thread overview]
Message-ID: <BYAPR21MB1270B53CFDDFD52AD942B3AEBF729@BYAPR21MB1270.namprd21.prod.outlook.com> (raw)
In-Reply-To: <BYAPR21MB127011609EBF6567126EBF83BF729@BYAPR21MB1270.namprd21.prod.outlook.com>
[-- Attachment #1: Type: text/plain, Size: 998 bytes --]
> 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
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next prev parent reply other threads:[~2021-12-11 7:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-10 3:30 Random high CPU utilization in blk-mq with the none scheduler Dexuan Cui
2021-12-11 1:29 ` Dexuan Cui
2021-12-11 2:04 ` Jens Axboe
2021-12-11 3:10 ` Dexuan Cui
2021-12-11 3:15 ` Jens Axboe
2021-12-11 3:44 ` Dexuan Cui
2021-12-11 7:09 ` Dexuan Cui [this message]
2021-12-11 14:21 ` Jens Axboe
2021-12-11 18:54 ` Dexuan Cui
2021-12-13 18:43 ` Jens Axboe
2021-12-14 0:43 ` Dexuan Cui
2021-12-13 3:23 ` Ming Lei
2021-12-13 4:20 ` Dexuan Cui
2021-12-13 7:38 ` Ming Lei
2021-12-14 0:31 ` Dexuan Cui
2021-12-14 0:53 ` Ming Lei
2021-12-14 3:09 ` Dexuan Cui
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