On 15/05/13 21:44, Paolo Bonzini wrote:
On Wed, May 15, 2013 at 02:56:03PM +0200, Paolo Bonzini wrote:
Il 14/05/2013 14:44, Osier Yang ha scritto:
QEMU introduced "discard" option for drive since commit a9384aff53,
<...> @var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap}) requests are ignored or passed to the filesystem. Some machine types may not support discard requests. </...>
This patch exposes the support in libvirt.
QEMU supported "discard" for "-drive" since v1.5.0-rc0: I would prefer to use ignore/unmap instead of off/on in libvirt. If we think there's any chance QEMU might gain a 3rd possible value for this setting, then I tend to agree with you that avoiding off/on would be desirable. Yes, the 3rd setting would be "anchor", i.e. when discarding keep any
Il 15/05/2013 15:17, Daniel P. Berrange ha scritto: preallocation but discard the data. This corresponds to the XFS ioctl XFS_IOC_ZERO_RANGE.
Agreed then, will make the change. Osier