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Subject: Re: [PATCH] blk-throttle: fix zero wait time for iops throttled group
To:     Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Liu Bo <bo.liu@linux.alibaba.com>, stable@vger.kernel.org
References: <156259979778.2486.6296077059654653057.stgit@buzz>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <30caacb5-4d45-016b-a97d-db8b37010218@kernel.dk>
Date:   Wed, 10 Jul 2019 08:00:40 -0600
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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