Messages in this thread | | | Date | Wed, 20 Nov 2013 09:21:47 -0700 | From | Jens Axboe <> | Subject | Re: [Regression x2, 3.13-git] virtio block mq hang, iostat busted on virtio devices |
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On 11/20/2013 01:07 AM, Christoph Hellwig wrote: >> Just stumbled on that too. You need one more, btw, for the sg failure >> case: >> >> >> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c >> index 588479d58f52..6a680d4de7f1 100644 >> --- a/drivers/block/virtio_blk.c >> +++ b/drivers/block/virtio_blk.c >> @@ -199,15 +199,16 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) >> >> spin_lock_irqsave(&vblk->vq_lock, flags); >> if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) { >> + virtqueue_kick(vblk->vq); >> spin_unlock_irqrestore(&vblk->vq_lock, flags); >> blk_mq_stop_hw_queue(hctx); >> - virtqueue_kick(vblk->vq); >> return BLK_MQ_RQ_QUEUE_BUSY; >> } >> - spin_unlock_irqrestore(&vblk->vq_lock, flags); >> >> if (last) >> virtqueue_kick(vblk->vq); >> + >> + spin_unlock_irqrestore(&vblk->vq_lock, flags); > > Note that virtqueue_kick can be split into a virtqueue_prepare_split > that needs the lock, and a virtqueue_notify that doesn't, but it might > not be nessecary to do that optimization right now.
Right, that would be easily doable. Seems it's in the realm of micro optimizations, but worth doing next time it's touched.
> Btw, how much do I need to bribe you to send mails where I don't have > step over 500 lines of dead quotes to find the actual patch?
Sorry, the next one was trimmed :-)
-- Jens Axboe
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