From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Cc: Mike Snitzer <snitzer@redhat.com>, Ming Lei <ming.lei@redhat.com>
Subject: Re: [PATCH v3] blk-mq: punt failed direct issue to dispatch list
Date: Fri, 07 Dec 2018 08:19:45 -0800 [thread overview]
Message-ID: <1544199585.185366.303.camel@acm.org> (raw)
In-Reply-To: <aa6abfa7-30c3-57d7-7369-754d514584f5@kernel.dk>
On Thu, 2018-12-06 at 22:17 -0700, Jens Axboe wrote:
> Instead of making special cases for what we can direct issue, and now
> having to deal with DM solving the livelock while still retaining a BUSY
> condition feedback loop, always just add a request that has been through
> ->queue_rq() to the hardware queue dispatch list. These are safe to use
> as no merging can take place there. Additionally, if requests do have
> prepped data from drivers, we aren't dependent on them not sharing space
> in the request structure to safely add them to the IO scheduler lists.
How about making blk_mq_sched_insert_request() complain if a request is passed
to it in which the RQF_DONTPREP flag has been set to avoid that this problem is
reintroduced in the future? Otherwise this patch looks fine to me.
Bart.
next prev parent reply other threads:[~2018-12-07 16:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-07 5:17 [PATCH v3] blk-mq: punt failed direct issue to dispatch list Jens Axboe
2018-12-07 8:24 ` Ming Lei
2018-12-07 10:50 ` Ming Lei
2018-12-07 15:15 ` Mike Snitzer
2018-12-07 16:19 ` Bart Van Assche [this message]
2018-12-07 16:24 ` Jens Axboe
2018-12-07 16:35 ` Jens Axboe
2018-12-07 16:41 ` Bart Van Assche
2018-12-07 16:45 ` Jens Axboe
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