Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753283AbdHJQkx (ORCPT ); Thu, 10 Aug 2017 12:40:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59282 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752776AbdHJQks (ORCPT ); Thu, 10 Aug 2017 12:40:48 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 40C557CB8A Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=rjones@redhat.com From: "Richard W.M. Jones" To: jejb@linux.vnet.ibm.com Cc: martin.petersen@oracle.com, mst@redhat.com, jasowang@redhat.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, hch@lst.de, pbonzini@redhat.com Subject: [PATCH 2/2] virtio: virtio_scsi: Set can_queue to the length of the virtqueue. Date: Thu, 10 Aug 2017 17:40:35 +0100 Message-Id: <20170810164035.19963-3-rjones@redhat.com> In-Reply-To: <20170810164035.19963-1-rjones@redhat.com> References: <20170810164035.19963-1-rjones@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 10 Aug 2017 16:40:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1270 Lines: 34 Since switching to blk-mq as the default in commit 5c279bd9e406 ("scsi: default to scsi-mq"), virtio-scsi LUNs consume about 10x as much kernel memory. qemu currently allocates a fixed 128 entry virtqueue. can_queue currently is set to 1024. But with indirect descriptors, each command in the queue takes 1 virtqueue entry, so the number of commands which can be queued is equal to the length of the virtqueue. Note I intend to send a patch to qemu to allow the virtqueue size to be configured from the qemu command line. Thanks Paolo Bonzini, Christoph Hellwig. Signed-off-by: Richard W.M. Jones --- drivers/scsi/virtio_scsi.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 9be211d68b15..d6b4ff634c0d 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -972,6 +972,8 @@ static int virtscsi_probe(struct virtio_device *vdev) if (err) goto virtscsi_init_failed; + shost->can_queue = virtqueue_get_vring_size(vscsi->req_vqs[0].vq); + cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1; shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue); shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF; -- 2.13.1