From: Christoph Hellwig <hch@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: axboe@kernel.dk, vgoyal@redhat.com, jgarzik@pobox.com,
davem@davemloft.net, linux-kernel@vger.kernel.org,
ctalbott@google.com, rni@google.com
Subject: Re: [PATCH 2/6] block: allow blk_execute_rq_nowait() to be called form IRQ context
Date: Fri, 21 Oct 2011 05:20:16 -0400 [thread overview]
Message-ID: <20111021092016.GA14388@infradead.org> (raw)
In-Reply-To: <1319169400-15706-3-git-send-email-tj@kernel.org>
On Thu, Oct 20, 2011 at 08:56:36PM -0700, Tejun Heo wrote:
> Currently blk_execute_rq_nowait() directly calls __blk_run_queue() and
> thus can't be called from IRQ context. This patch updates it to use
> blk_run_queue_async() instead. This will be used to unexport
> elv_add_request().
>
> This changes how queue is kicked after blk_execute_rq_nowait() but
> it's hardly a hot path and the effect shouldn't be noticeable.
It actually very much is a fasthpath for many of it's users, e.g. the
SCSI tape drivers, the OSD layer and the target scsi passthrough
backend.
I don't think blindly adding a context switch here without benchmarking
is doable. Just add variants that do the workqueue dance or not.
next prev parent reply other threads:[~2011-10-21 9:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-21 3:56 [PATCHSET block:for-3.2/core] further updates to blk_cleanup_queue() Tejun Heo
2011-10-21 3:56 ` [PATCH 1/6] block, sx8: kill blk_insert_request() Tejun Heo
2011-10-21 4:03 ` Jeff Garzik
2011-10-21 3:56 ` [PATCH 2/6] block: allow blk_execute_rq_nowait() to be called form IRQ context Tejun Heo
2011-10-21 9:20 ` Christoph Hellwig [this message]
2011-10-21 18:13 ` Tejun Heo
2011-10-21 3:56 ` [PATCH 3/6] block, ide: unexport elv_add_request() Tejun Heo
2011-10-21 3:56 ` [PATCH 4/6] block: add blk_queue_dead() Tejun Heo
2011-10-21 3:56 ` [PATCH 5/6] block: fix drain_all condition in blk_drain_queue() Tejun Heo
2011-10-21 3:56 ` [PATCH 6/6] block: add missing blk_queue_dead() checks Tejun Heo
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