From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Shaohua Li <shli@kernel.org>, Dave Chinner <david@fromorbit.com>,
linux-kernel@vger.kernel.org
Subject: Re: [Regression x2, 3.13-git] virtio block mq hang, iostat busted on virtio devices
Date: Wed, 20 Nov 2013 09:21:47 -0700 [thread overview]
Message-ID: <528CE19B.8020004@kernel.dk> (raw)
In-Reply-To: <20131120080702.GB13147@infradead.org>
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
next prev parent reply other threads:[~2013-11-20 16:22 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 8:02 [Regression x2, 3.13-git] virtio block mq hang, iostat busted on virtio devices Dave Chinner
2013-11-19 10:36 ` Christoph Hellwig
2013-11-19 16:05 ` Jens Axboe
2013-11-19 16:09 ` Christoph Hellwig
2013-11-19 16:16 ` Jens Axboe
2013-11-19 21:30 ` Dave Chinner
2013-11-19 21:40 ` Jens Axboe
2013-11-19 20:15 ` Jens Axboe
2013-11-19 21:20 ` Jens Axboe
2013-11-19 21:34 ` Dave Chinner
2013-11-19 21:43 ` Jens Axboe
2013-11-19 22:42 ` Jens Axboe
2013-11-19 22:51 ` Jens Axboe
2013-11-19 23:23 ` Dave Chinner
2013-11-19 23:59 ` Jens Axboe
2013-11-20 0:08 ` Jens Axboe
2013-11-20 1:44 ` Shaohua Li
2013-11-20 1:54 ` Jens Axboe
2013-11-20 2:02 ` Jens Axboe
2013-11-20 2:53 ` Dave Chinner
2013-11-20 3:12 ` Jens Axboe
2013-11-20 8:07 ` Christoph Hellwig
2013-11-20 16:21 ` Jens Axboe [this message]
2013-11-20 8:04 ` Christoph Hellwig
2013-11-20 16:20 ` Jens Axboe
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