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73c0a148af
In some versions of qemu, both virtio-blk-pci and virtio-net-pci
devices can have an event_idx setting that determines some details of
event processing. When it is enabled, it "reduces the number of
interrupts and exits for the guest". qemu will automatically enable
this feature when it is available, but there may be cases where this
new feature could actually make performance worse (NB: no such case
has been found so far).
As a safety switch in case such a situation is encountered in the
field, this patch adds a new attribute "event_idx" to the <driver>
element of both disk and interface devices. event_idx can be set to
"on" (to force event_idx on in case qemu has it disabled by default)
or "off" (for force event_idx off). In the case that event_idx support
isn't present in qemu, the attribute is ignored (this on the advice of
the qemu developer).
docs/formatdomain.html.in: document the new flag (marking it as
"don't mess with this!"
docs/schemas/domain.rng: add event_idx in appropriate places
src/conf/domain_conf.[ch]: add event_idx to parser and formatter
src/libvirt_private.syms: export
virDomainVirtioEventIdx(From|To)String
src/qemu/qemu_capabilities.[ch]: detect and report event_idx in
disk/net
src/qemu/qemu_command.c: add event_idx parameter to qemu commandline
when appropriate.
tests/qemuxml2argvdata/qemuxml2argv-event_idx.args,
tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml,
tests/qemuxml2argvtest.c,
tests/qemuxml2xmltest.c: test cases for event_idx.
58 lines
1.9 KiB
XML
58 lines
1.9 KiB
XML
<domain type='qemu'>
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<name>test</name>
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<uuid>bba65c0e-c049-934f-b6aa-4e2c0582acdf</uuid>
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<memory>1048576</memory>
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<currentMemory>1048576</currentMemory>
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<vcpu>1</vcpu>
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<os>
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<type arch='x86_64' machine='pc-0.13'>hvm</type>
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<boot dev='cdrom'/>
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<boot dev='hd'/>
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<bootmenu enable='yes'/>
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</os>
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<clock offset='utc'/>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>restart</on_crash>
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<devices>
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<emulator>/usr/bin/qemu</emulator>
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<disk type='file' device='disk'>
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<driver name='qemu' type='qcow2' event_idx='on'/>
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<source file='/var/lib/libvirt/images/f14.img'/>
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<target dev='vda' bus='virtio'/>
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<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
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</disk>
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<disk type='file' device='cdrom'>
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<driver name='qemu' type='raw'/>
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<source file='/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso'/>
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<target dev='hdc' bus='ide'/>
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<readonly/>
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<address type='drive' controller='0' bus='1' unit='0'/>
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</disk>
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<controller type='virtio-serial' index='0'>
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<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
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</controller>
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<controller type='ide' index='0'/>
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<interface type='user'>
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<mac address='52:54:00:e5:48:58'/>
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<model type='virtio'/>
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<driver name='vhost' event_idx='off'/>
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</interface>
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<serial type='pty'>
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<target port='0'/>
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</serial>
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<console type='pty'>
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<target type='serial' port='0'/>
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</console>
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<input type='mouse' bus='ps2'/>
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<graphics type='vnc' port='5091' autoport='no' listen='127.0.0.1'>
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<listen type='address' address='127.0.0.1'/>
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</graphics>
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<video>
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<model type='vga' vram='9216' heads='1'/>
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<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
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</video>
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<memballoon model='virtio'/>
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</devices>
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</domain>
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