linux-kernel - Re: [PATCH] blk-throttle: fix zero wait time for iops throttled group

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Message-ID: <30caacb5-4d45-016b-a97d-db8b37010218@kernel.dk>
Date:   Wed, 10 Jul 2019 08:00:40 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Liu Bo <bo.liu@...ux.alibaba.com>, stable@...r.kernel.org
Subject: Re: [PATCH] blk-throttle: fix zero wait time for iops throttled group

On 7/8/19 9:29 AM, Konstantin Khlebnikov wrote:
> After commit 991f61fe7e1d ("Blk-throttle: reduce tail io latency when iops
> limit is enforced") wait time could be zero even if group is throttled and
> cannot issue requests right now. As a result throtl_select_dispatch() turns
> into busy-loop under irq-safe queue spinlock.
> 
> Fix is simple: always round up target time to the next throttle slice.

Applied, thanks. In the future, please break lines at 72 chars in
commit messages, I fixed it up.

-- 
Jens Axboe