From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753282AbdHJQ5G (ORCPT ); Thu, 10 Aug 2017 12:57:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37114 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752520AbdHJQ5E (ORCPT ); Thu, 10 Aug 2017 12:57:04 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com EDF477BE32 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.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 v2 2/2] virtio: virtio_scsi: Set can_queue to the length of the virtqueue. Date: Thu, 10 Aug 2017 17:56:52 +0100 Message-Id: <20170810165652.21515-3-rjones@redhat.com> In-Reply-To: <20170810165652.21515-1-rjones@redhat.com> References: <20170810165652.21515-1-rjones@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 10 Aug 2017 16:57:04 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 9be211d68b15..7c28e8d4955a 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -818,7 +818,6 @@ static struct scsi_host_template virtscsi_host_template_single = { .eh_timed_out = virtscsi_eh_timed_out, .slave_alloc = virtscsi_device_alloc, - .can_queue = 1024, .dma_boundary = UINT_MAX, .use_clustering = ENABLE_CLUSTERING, .target_alloc = virtscsi_target_alloc, @@ -839,7 +838,6 @@ static struct scsi_host_template virtscsi_host_template_multi = { .eh_timed_out = virtscsi_eh_timed_out, .slave_alloc = virtscsi_device_alloc, - .can_queue = 1024, .dma_boundary = UINT_MAX, .use_clustering = ENABLE_CLUSTERING, .target_alloc = virtscsi_target_alloc, @@ -972,6 +970,8 @@ 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