linux-kernel - Re: [v5.12-rc2 regression] io_uring: high CPU use after suspend-to-ram

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Message-ID: <YEg7rmuMjV3FyGBR@kevinlocke.name>
Date:   Tue, 9 Mar 2021 20:23:26 -0700
From:   Kevin Locke <kevin@...inlocke.name>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     io-uring@...r.kernel.org, linux-kernel@...r.kernel.org,
        rafael.j.wysocki@...el.com
Subject: Re: [v5.12-rc2 regression] io_uring: high CPU use after
 suspend-to-ram

On Tue, 2021-03-09 at 19:48 -0700, Jens Axboe wrote:
> On 3/9/21 6:55 PM, Kevin Locke wrote:
>> With kernel 5.12-rc2 (and torvalds/master 144c79ef3353), if mpd is
>> playing or paused when my system is suspended-to-ram, when the system is
>> resumed mpd will consume ~200% CPU until killed.  It continues to
>> produce audio and respond to pause/play commands, which do not affect
>> CPU usage.  This occurs with either pulse (to PulseAudio or
>> PipeWire-as-PulseAudio) or alsa audio_output.
> 
> The below makes it work as expected for me - but I don't quite
> understand why we're continually running after the freeze. Adding Rafael
> to help understand this.

I can confirm that your patch resolves the high CPU usage after suspend
on my system as well.  Many thanks!

Tested-by: Kevin Locke <kevin@...inlocke.name>

Happy to test any future revisions as well.

Thanks again,
Kevin