Re: [PATCH Libvirt v2 1/3] conf: Add 'virtio_discard' and 'virtio_write_zeroes' attributes

From: Hyman Huang(黄勇) <yong.huang(a)smartx.com&gt; Add 'virtio_discard' and 'virtio_write_zeroes' attribute to control whether discard and write-zeroes requests are handled by the virtio-blk device. To distinguish the attributes in block drive layer, use the 'virtio' prefix to indicate that these attributes are specific for virtio-blk. Signed-off-by: Hyman Huang(黄勇) <yong.huang(a)smartx.com&gt; --- docs/formatdomain.rst | 8 ++++++++ src/conf/domain_conf.c | 16 ++++++++++++++++ src/conf/domain_conf.h | 2 ++ src/conf/schemas/domaincommon.rng | 10 ++++++++++ src/conf/storage_source_conf.c | 2 ++ src/conf/storage_source_conf.h | 2 ++ src/qemu/qemu_domain.c | 2 ++ src/qemu/qemu_driver.c | 4 +++- src/vz/vz_utils.c | 12 ++++++++++++ 9 files changed, 57 insertions(+), 1 deletion(-) diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index 4af0b82569..7be12ff08e 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -3259,6 +3259,14 @@ paravirtualized driver is specified via the ``disk`` element. value can be either "unmap" (allow the discard request to be passed) or "ignore" (ignore the discard request). :since:`Since 1.0.6 (QEMU and KVM only)` + - The optional ``virtio_discard`` and ``virtio_write_zeroes`` are attributes + that control whether discard and write-zeroes requests are handled by the + virtio-blk device. The feature is based on DISCARD and WRITE_ZEROES + commands introduced in virtio-blk protocol to improve performance when + using SSD backend. The value can be either 'on' or 'off'. Note that + ``discard`` and ``write_zeroes`` implementations in the block drive layer + are parts of the feature logically and should be turned on when enabling + the feature. :since:`Since 9.6.0 (QEMU and KVM only)`