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authorStefan Hajnoczi <stefanha@redhat.com>2020-10-01 15:46:03 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2020-10-23 13:42:16 +0100
commitd9b495f9c6a943c9bbd50f7469efb645c23009c3 (patch)
treed8ca95db872445d606fbe7eaa5577e99fa74d925 /qapi
parentf51d23c80af73c95e0ce703ad06a300f1b3d63ef (diff)
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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 <stefanha@redhat.com> Acked-by: Markus Armbruster <armbru@redhat.com> Message-id: 20201001144604.559733-2-stefanha@redhat.com [Fixed accidental tab characters as suggested by Markus Armbruster --Stefan] Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'qapi')
-rw-r--r--qapi/block-export.json10
1 files changed, 7 insertions, 3 deletions
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 8a4ced8..480c497 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' },