Re: [libvirt] [PATCH v2] qemu: Add option to enable/disable IOEventFD feature

This feature allows QEMU to achieve higher throughput, but is available only in recent versions. It is accessible via ioeventfd attribute with accepting values 'on', 'off'. Only experienced users needs to set this, because QEMU defaults to 'on', meaning higher performance. Translates into virtio-{blk|net}-pci.ioeventfd option. --- diff to v1: - rebase to current HEAD docs/formatdomain.html.in | 15 ++++++++++++- docs/schemas/domain.rng | 14 +++++++++++++ src/conf/domain_conf.c | 44 +++++++++++++++++++++++++++++++++++++++++- src/conf/domain_conf.h | 12 +++++++++++ src/libvirt_private.syms | 2 + src/qemu/qemu_capabilities.c | 2 + src/qemu/qemu_capabilities.h | 1 + src/qemu/qemu_command.c | 23 +++++++++++++++++++++ tests/qemuhelptest.c | 3 +- 9 files changed, 112 insertions(+), 4 deletions(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 989dcf6..a4d7cbd 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -767,7 +767,7 @@ &lt;/disk&gt; ... &lt;disk type='network'&gt; - &lt;driver name="qemu" type="raw" io="threads"/&gt; + &lt;driver name="qemu" type="raw" io="threads" ioeventfd="on"/&gt; &lt;source protocol="sheepdog" name="image_name"&gt; &lt;host name="hostname" port="7000"/&gt; &lt;/source&gt; @@ -851,6 +851,11 @@ policies on I/O; qemu guests support "threads" and "native". <span class="since">Since 0.8.8</span> </li> + <li> + The optional <code>ioeventfd</code> attribute enables or disables + IOEventFD feature for virtqueue notify. The value can be either + 'on' or 'off'. + <span class="since">Since 0.9.2 (QEMU and KVM only)</span>