[libvirt] [PATCH v2] qemu: Support copy on read for disk
Eric Blake
eblake at redhat.com
Fri Jan 13 00:11:54 UTC 2012
On 01/12/2012 03:13 AM, Osier Yang wrote:
> The new introduced optional attribute "copy_on_read</code> controls
> wether to copy read backing file into the image file. The value can
s/wether/whether/
> be either "on" or "off". Copy-on-read avoids accessing the same backing
> file sectors repeatedly and is useful when the backing file is over a
> slow network. By default copy-on-read is off.
> ---
> docs/formatdomain.html.in | 9 ++++
> docs/schemas/domaincommon.rng | 11 ++++
> src/conf/domain_conf.c | 24 +++++++++-
> src/conf/domain_conf.h | 10 ++++
> src/libvirt_private.syms | 2 +
> src/qemu/qemu_capabilities.c | 3 +
> src/qemu/qemu_capabilities.h | 1 +
> src/qemu/qemu_command.c | 11 ++++
> tests/qemuhelptest.c | 3 +-
> .../qemuxml2argv-disk-copy_on_read.args | 11 ++++
> .../qemuxml2argv-disk-copy_on_read.xml | 50 ++++++++++++++++++++
> tests/qemuxml2argvtest.c | 4 ++
> 12 files changed, 137 insertions(+), 2 deletions(-)
> create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.args
> create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-copy_on_read.xml
>
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index 42e23a1..3a42ebb 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -1202,6 +1202,15 @@
> <b>In general you should leave this option alone, unless you
> are very certain you know what you are doing.</b>
> </li>
> + <li>
> + The optional <code>copy_on_read</code> attribute controls
> + wether to copy read backing file into the image file. The
> + value can be either "on" or "off".
> + Copy-on-read avoids accessing the same backing file sectors
> + repeatedly and is useful when the backing file is over a slow
> + network. By default copy-on-read is off.
> + <span class='since'>Since 0.9.9 (QEMU and KVM only)</span>
0.9.10
> +++ b/docs/schemas/domaincommon.rng
> @@ -958,6 +958,9 @@
> <optional>
> <ref name="event_idx"/>
> </optional>
> + <optional>
> + <ref name="copy_on_read"/>
> + </optional>
Your placement as an attribute of <driver> makes sense - the guest sees
no difference in behavior, so this really is an option for just how the
host behaves.
Looks pretty clean. ACK with the minor doc nit fixed.
--
Eric Blake eblake at redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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