From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752219AbaIFXHi (ORCPT ); Sat, 6 Sep 2014 19:07:38 -0400 Received: from casper.infradead.org ([85.118.1.10]:60597 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751708AbaIFXHh (ORCPT ); Sat, 6 Sep 2014 19:07:37 -0400 From: Christoph Hellwig To: Rusty Russell , "Michael S. Tsirkin" Cc: Jens Axboe , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH] virtio_blk: merge S/G list entries by default Date: Sat, 6 Sep 2014 16:09:54 -0700 Message-Id: <1410044994-14943-1-git-send-email-hch@lst.de> X-Mailer: git-send-email 1.9.1 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Most virtio setups have a fairly limited number of ring entries available. Enable S/G entry merging by default to fit into less of them. This restores the behavior at time of the virtio-blk blk-mq conversion, which was changed by commit "block: add queue flag for disabling SG merging" which made the behavior optional, but didn't update the existing drivers to keep their previous behavior. Signed-off-by: Christoph Hellwig --- 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 0a58140..311b857 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -634,7 +634,7 @@ static int virtblk_probe(struct virtio_device *vdev) vblk->tag_set.ops = &virtio_mq_ops; vblk->tag_set.queue_depth = virtblk_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_SG_MERGE; vblk->tag_set.cmd_size = sizeof(struct virtblk_req) + sizeof(struct scatterlist) * sg_elems; -- 1.9.1