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Message-ID: <b4350274-7219-1d1f-7a39-3f445c081fd1@kernel.dk>
Date: Sat, 11 Dec 2021 07:21:29 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Dexuan Cui <decui@...rosoft.com>,
"'ming.lei@...hat.com'" <ming.lei@...hat.com>,
'Christoph Hellwig' <hch@....de>,
"'linux-block@...r.kernel.org'" <linux-block@...r.kernel.org>
Cc: Long Li <longli@...rosoft.com>,
"Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
Subject: Re: Random high CPU utilization in blk-mq with the none scheduler
On 12/11/21 12:09 AM, Dexuan Cui wrote:
>> From: Dexuan Cui
>> Sent: Friday, December 10, 2021 7:45 PM
>>
>>> From: Jens Axboe <axboe@...nel.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.
Sorry, can you do:
# perf report -g --no-children
instead?
--
Jens Axboe
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