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qemu: Implement virtio-blk queue-size option

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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>
This commit is contained in:
Hiroki Narukawa 2021-09-09 12:34:48 +09:00 committed by Peter Krempa
parent ad209e7dbc
commit 2d6d67e154
4 changed files with 29 additions and 2 deletions
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3
src/qemu/qemu_command.c
View File

@ -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);

6
src/qemu/qemu_validate.c
View File

@ -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:

10
tests/qemuxml2argvdata/disk-virtio-queues.x86_64-latest.args
View File

@ -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

12
tests/qemuxml2argvdata/disk-virtio-queues.xml
View File

@ -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>