qemu: Implement virtio-blk queue-size option

The option "queue-size" in virtio-blk was added in qemu-2.12.0, and
default value increased from qemu-5.0.0.

However, increasing this value may lead to drop of random access
performance.

Signed-off-by: Hiroki Narukawa <hnarukaw@yahoo-corp.jp>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 73868ab4b731813354d4fe27d0af53c15057910e..95f0a26564d8655581731cb36905f738d026744b 100644 (file)
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1738,6 +1738,9 @@ qemuBuildDiskDeviceStr(const virDomainDef *def,
         if (disk->queues) {
             virBufferAsprintf(&opt, ",num-queues=%u", disk->queues);
         }
+        if (disk->queue_size > 0) {
+            virBufferAsprintf(&opt, ",queue-size=%u", disk->queue_size);
+        }
 
         qemuBuildVirtioOptionsStr(&opt, disk->virtio);
 

diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index 6b685881a83f6719a97acb0b74b2d51e8ff353e1..6b1a0f6c02939dd3b1e656cfba4fea15d8debce1 100644 (file)
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -2826,6 +2826,12 @@ qemuValidateDomainDeviceDefDiskFrontend(const virDomainDiskDef *disk,
                              "QEMU binary"));
             return -1;
         }
+        if (disk->queue_size > 0 &&
+            !virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_BLK_NUM_QUEUES)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("queue-size property isn't supported by this QEMU binary"));
+            return -1;
+        }
         break;
 
     case VIR_DOMAIN_DISK_BUS_USB:

diff --git a/tests/qemuxml2argvdata/disk-virtio-queues.x86_64-latest.args b/tests/qemuxml2argvdata/disk-virtio-queues.x86_64-latest.args
index 6637088a35d8a033a8eb852c4ba33a3081440385..b1ff6de857495df457fdbe1c214fe02fddfc3271 100644 (file)
--- a/tests/qemuxml2argvdata/disk-virtio-queues.x86_64-latest.args
+++ b/tests/qemuxml2argvdata/disk-virtio-queues.x86_64-latest.args
@@ -27,9 +27,15 @@ XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \
 -no-acpi \
 -boot strict=on \
 -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \
--blockdev '{"driver":"file","filename":"/tmp/data.img","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"driver":"file","filename":"/tmp/data.img","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"node-name":"libvirt-3-format","read-only":false,"driver":"raw","file":"libvirt-3-storage"}' \
+-device virtio-blk-pci,num-queues=4,bus=pci.0,addr=0x3,drive=libvirt-3-format,id=virtio-disk0,bootindex=1 \
+-blockdev '{"driver":"file","filename":"/tmp/data1.img","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}' \
+-blockdev '{"node-name":"libvirt-2-format","read-only":false,"driver":"raw","file":"libvirt-2-storage"}' \
+-device virtio-blk-pci,queue-size=256,bus=pci.0,addr=0x4,drive=libvirt-2-format,id=virtio-disk1 \
+-blockdev '{"driver":"file","filename":"/tmp/data2.img","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
 -blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"raw","file":"libvirt-1-storage"}' \
--device virtio-blk-pci,num-queues=4,bus=pci.0,addr=0x3,drive=libvirt-1-format,id=virtio-disk0,bootindex=1 \
+-device virtio-blk-pci,num-queues=4,queue-size=256,bus=pci.0,addr=0x5,drive=libvirt-1-format,id=virtio-disk2 \
 -audiodev id=audio1,driver=none \
 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
 -msg timestamp=on

diff --git a/tests/qemuxml2argvdata/disk-virtio-queues.xml b/tests/qemuxml2argvdata/disk-virtio-queues.xml
index ea1001bdd4cfaff275423e62b6acd387ce027e2b..3cfa958c97a177bf567182ba1fd9db7e4bb40748 100644 (file)
--- a/tests/qemuxml2argvdata/disk-virtio-queues.xml
+++ b/tests/qemuxml2argvdata/disk-virtio-queues.xml
@@ -23,6 +23,18 @@
       <target dev='vda' bus='virtio'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
     </disk>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='raw' queue_size='256'/>
+      <source file='/tmp/data1.img'/>
+      <target dev='vdb' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+    </disk>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='raw' queues='4' queue_size='256'/>
+      <source file='/tmp/data2.img'/>
+      <target dev='vdc' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
+    </disk>
     <controller type='usb' index='0' model='piix3-uhci'>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
     </controller>