From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC] virtio: Support releasing lock during kick Date: Sun, 19 Jun 2011 09:55:07 -0400 Message-ID: <20110619135507.GA25728@infradead.org> References: <1277328242-10685-1-git-send-email-stefanha@linux.vnet.ibm.com> <20110619074841.GA8613@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20110619074841.GA8613@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" Cc: axboe@kernel.dk, Stefan Hajnoczi , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, hch@infradead.org List-Id: virtualization@lists.linuxfoundation.org On Sun, Jun 19, 2011 at 10:48:41AM +0300, Michael S. Tsirkin wrote: > diff --git a/block/blk-core.c b/block/blk-core.c > index 4ce953f..a8672ec 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -433,6 +433,8 @@ void blk_run_queue(struct request_queue *q) > spin_lock_irqsave(q->queue_lock, flags); > __blk_run_queue(q); > spin_unlock_irqrestore(q->queue_lock, flags); > + if (q->request_done) > + q->request_done(q); We have quite a few cases where __blk_run_queue is called directly, and one more (although not applicable to virtio-blk) that calls ->request_fn directly. I think Stefan's way is the way to go for now, releasing and reacquiring the queue lock once in ->request_fn is much less than the common IDE and SCSI setups do today. Eventually ->queue_lock should be split from the driver-internal lock, and we could do a more efficient calling convention than the one per request blk_peek_request. I've started looking into that, but it's going to take a while.