linux-kernel - Re: [PATCH block/for-5.5-fixes] iocost: over-budget forced IOs should schedule async delay

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Date:   Mon, 16 Dec 2019 16:10:32 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Tejun Heo <tj@...nel.org>
Cc:     linux-block@...r.kernel.org, kernel-team@...com,
        linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
        Josef Bacik <josef@...icpanda.com>
Subject: Re: [PATCH block/for-5.5-fixes] iocost: over-budget forced IOs should
 schedule async delay

On 12/16/19 2:34 PM, Tejun Heo wrote:
> When over-budget IOs are force-issued through root cgroup,
> iocg_kick_delay() adjusts the async delay accordingly but doesn't
> actually schedule async throttle for the issuing task.  This bug is
> pretty well masked because sooner or later the offending threads are
> gonna get directly throttled on regular IOs or have async delay
> scheduled by mem_cgroup_throttle_swaprate().
> 
> However, it can affect control quality on filesystem metadata heavy
> operations.  Let's fix it by invoking blkcg_schedule_throttle() when
> iocg_kick_delay() says async delay is needed.

Applied, thanks Tejun.

-- 
Jens Axboe