From d9b495f9c6a943c9bbd50f7469efb645c23009c3 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 1 Oct 2020 15:46:03 +0100 Subject: [PATCH] block/export: add vhost-user-blk multi-queue support Allow the number of queues to be configured using --export vhost-user-blk,num-queues=N. This setting should match the QEMU --device vhost-user-blk-pci,num-queues=N setting but QEMU vhost-user-blk.c lowers its own value if the vhost-user-blk backend offers fewer queues than QEMU. The vhost-user-blk-server.c code is already capable of multi-queue. All virtqueue processing runs in the same AioContext. No new locking is needed. Add the num-queues=N option and set the VIRTIO_BLK_F_MQ feature bit. Note that the feature bit only announces the presence of the num_queues configuration space field. It does not promise that there is more than 1 virtqueue, so we can set it unconditionally. I tested multi-queue by running a random read fio test with numjobs=4 on an -smp 4 guest. After the benchmark finished the guest /proc/interrupts file showed activity on all 4 virtio-blk MSI-X. The /sys/block/vda/mq/ directory shows that Linux blk-mq has 4 queues configured. An automated test is included in the next commit. Signed-off-by: Stefan Hajnoczi Acked-by: Markus Armbruster Message-id: 20201001144604.559733-2-stefanha@redhat.com [Fixed accidental tab characters as suggested by Markus Armbruster --Stefan] Signed-off-by: Stefan Hajnoczi --- block/export/vhost-user-blk-server.c | 24 ++++++++++++++++++------ qapi/block-export.json | 10 +++++++--- 2 files changed, 25 insertions(+), 9 deletions(-) diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c index 286eb5fb9a..41f4933d6e 100644 --- a/block/export/vhost-user-blk-server.c +++ b/block/export/vhost-user-blk-server.c @@ -21,7 +21,7 @@ #include "util/block-helpers.h" enum { - VHOST_USER_BLK_MAX_QUEUES = 1, + VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1, }; struct virtio_blk_inhdr { unsigned char status; @@ -242,6 +242,7 @@ static uint64_t vu_blk_get_features(VuDev *dev) 1ull << VIRTIO_BLK_F_DISCARD | 1ull << VIRTIO_BLK_F_WRITE_ZEROES | 1ull << VIRTIO_BLK_F_CONFIG_WCE | + 1ull << VIRTIO_BLK_F_MQ | 1ull << VIRTIO_F_VERSION_1 | 1ull << VIRTIO_RING_F_INDIRECT_DESC | 1ull << VIRTIO_RING_F_EVENT_IDX | @@ -338,7 +339,9 @@ static void blk_aio_detach(void *opaque) static void vu_blk_initialize_config(BlockDriverState *bs, - struct virtio_blk_config *config, uint32_t blk_size) + struct virtio_blk_config *config, + uint32_t blk_size, + uint16_t num_queues) { config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; config->blk_size = blk_size; @@ -346,7 +349,7 @@ vu_blk_initialize_config(BlockDriverState *bs, config->seg_max = 128 - 2; config->min_io_size = 1; config->opt_io_size = 1; - config->num_queues = VHOST_USER_BLK_MAX_QUEUES; + config->num_queues = num_queues; config->max_discard_sectors = 32768; config->max_discard_seg = 1; config->discard_sector_alignment = config->blk_size >> 9; @@ -368,6 +371,7 @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts, BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk; Error *local_err = NULL; uint64_t logical_block_size; + uint16_t num_queues = VHOST_USER_BLK_NUM_QUEUES_DEFAULT; vexp->writable = opts->writable; vexp->blkcfg.wce = 0; @@ -385,15 +389,23 @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts, } vexp->blk_size = logical_block_size; blk_set_guest_block_size(exp->blk, logical_block_size); + + if (vu_opts->has_num_queues) { + num_queues = vu_opts->num_queues; + } + if (num_queues == 0) { + error_setg(errp, "num-queues must be greater than 0"); + return -EINVAL; + } + vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg, - logical_block_size); + logical_block_size, num_queues); blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach, vexp); if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx, - VHOST_USER_BLK_MAX_QUEUES, &vu_blk_iface, - errp)) { + num_queues, &vu_blk_iface, errp)) { blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach, vexp); return -EADDRNOTAVAIL; diff --git a/qapi/block-export.json b/qapi/block-export.json index 8a4ced817f..480c497690 100644 --- a/qapi/block-export.json +++ b/qapi/block-export.json @@ -93,11 +93,15 @@ # SocketAddress types are supported. Passed fds must be UNIX domain # sockets. # @logical-block-size: Logical block size in bytes. Defaults to 512 bytes. +# @num-queues: Number of request virtqueues. Must be greater than 0. Defaults +# to 1. # # Since: 5.2 ## { 'struct': 'BlockExportOptionsVhostUserBlk', - 'data': { 'addr': 'SocketAddress', '*logical-block-size': 'size' } } + 'data': { 'addr': 'SocketAddress', + '*logical-block-size': 'size', + '*num-queues': 'uint16'} } ## # @NbdServerAddOptions: @@ -233,8 +237,8 @@ { 'union': 'BlockExportOptions', 'base': { 'type': 'BlockExportType', 'id': 'str', - '*fixed-iothread': 'bool', - '*iothread': 'str', + '*fixed-iothread': 'bool', + '*iothread': 'str', 'node-name': 'str', '*writable': 'bool', '*writethrough': 'bool' },