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Tsirkin" To: Li Feng Cc: Jens Axboe , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Xuan Zhuo , "open list:BLOCK LAYER" , open list , "open list:VIRTIO BLOCK AND SCSI DRIVERS" Subject: Re: [PATCH] virtio_blk: set the default scheduler to none Message-ID: <20231225092010-mutt-send-email-mst@kernel.org> References: <20231207043118.118158-1-fengli@smartx.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20231207043118.118158-1-fengli@smartx.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Dec 07, 2023 at 12:31:05PM +0800, Li Feng wrote: > virtio-blk is generally used in cloud computing scenarios, where the > performance of virtual disks is very important. The mq-deadline scheduler > has a big performance drop compared to none with single queue. In my tests, > mq-deadline 4k readread iops were 270k compared to 450k for none. So here > the default scheduler of virtio-blk is set to "none". > > Signed-off-by: Li Feng I dropped this for now, pls try to address comments by Christoph/Paolo if it's still needed > --- > drivers/block/virtio_blk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index d53d6aa8ee69..5183ec8e00be 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -1367,7 +1367,7 @@ static int virtblk_probe(struct virtio_device *vdev) > vblk->tag_set.ops = &virtio_mq_ops; > vblk->tag_set.queue_depth = queue_depth; > vblk->tag_set.numa_node = NUMA_NO_NODE; > - vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; > + vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_NO_SCHED_BY_DEFAULT; > vblk->tag_set.cmd_size = > sizeof(struct virtblk_req) + > sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT; > -- > 2.42.0