From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org
Subject: Re: [PATCH v2] block: fix peeking requests during PM
Date: Mon, 23 Oct 2017 18:43:16 +0800 [thread overview]
Message-ID: <20171023104315.GA30252@ming.t460p> (raw)
In-Reply-To: <20171020144523.4585-1-hch@lst.de>
On Fri, Oct 20, 2017 at 04:45:23PM +0200, Christoph Hellwig wrote:
> We need to look for an active PM request until the next softbarrier
> instead of looking for the first non-PM request. Otherwise any cause
> of request reordering might starve the PM request(s).
Hi Christoph,
Could you share us how the starve is caused? Looks all PM
request is run via scsi_execute(), and the caller is always
waiting for the completion of PM request.
Especially PM request is run after SCSI device is in quiesce
state, during that time, no normal(non-preempt) request can
enter queue after the making quiesce safe patchset is merged.
--
Ming
next prev parent reply other threads:[~2017-10-23 10:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-20 14:45 [PATCH v2] block: fix peeking requests during PM Christoph Hellwig
2017-10-23 10:43 ` Ming Lei [this message]
2017-10-24 14:45 ` Christoph Hellwig
2017-11-04 11:40 ` Christoph Hellwig
2017-11-04 14:17 ` Jens Axboe
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