[libvirt] [PATCH v2] qemu: Add option to enable/disable IOEventFD feature
Daniel P. Berrange
berrange at redhat.com
Tue May 17 14:56:11 UTC 2011
On Tue, May 17, 2011 at 04:49:17PM +0200, Michal Privoznik wrote:
> 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 @@
> </disk>
> ...
> <disk type='network'>
> - <driver name="qemu" type="raw" io="threads"/>
> + <driver name="qemu" type="raw" io="threads" ioeventfd="on"/>
> <source protocol="sheepdog" name="image_name">
> <host name="hostname" port="7000"/>
> </source>
> @@ -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>
This is a qemu specific attribute name & description. IMHO we shouldn't
be exposing that directly. Who even knows what effect it actually has
on the guests...
Daniel
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