[libvirt] [PATCH v4 0/2] Add support for qcow2 cache

[John Ferlan]

On 09/13/2017 05:21 AM, Liu Qing wrote:
> Qcow2 small IO random write performance will drop dramatically if the l2
> cache table could not cover the whole disk. This will be a lot of l2
> cache table RW operations if cache miss happens frequently.
>  
> This patch exports the qcow2 driver parameter
> l2-cache-size/refcount-cache-size, first added in Qemu 2.2, and
> cache-clean-interval, first added in Qemu 2.5, in libvirt.
> 
> Change since v3: a) copy qcow2 cache configurion from source to backing
>                     to backing file source.


The difference you list doesn't make any sense. The only difference
between this an V3 is removing the qemu_command.c from patch1.  I did a
git diff between the two trees I have from your patches:

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c3b81e138..e95683965 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -14318,11 +14318,6 @@
qemuDomainSnapshotDiskDataCollect(virQEMUDriverPtr driver,
         if (!(dd->src = virStorageSourceCopy(snap->def->disks[i].src,
false)))
             goto error;

-        /* keep the qcow2 cache configuration */
-        dd->src->l2_cache_size = vm->def->disks[i]->src->l2_cache_size;
-        dd->src->refcount_cache_size =
vm->def->disks[i]->src->refcount_cache_size;
-        dd->src->cache_clean_interval =
vm->def->disks[i]->src->cache_clean_interval;
-
         if (virStorageSourceInitChainElement(dd->src, dd->disk->src,
false) < 0)
             goto error;


I'll stick with the v3 version and adjustments from comments that I made.

John
> Liu Qing (2):
>   conf, docs: Add qcow2 cache configuration support
>   qemu: add capability checking for qcow2 cache configuration
> 
>  docs/formatdomain.html.in                          | 43 ++++++++++
>  docs/schemas/domaincommon.rng                      | 35 ++++++++
>  src/conf/domain_conf.c                             | 95 +++++++++++++++++++++-
>  src/qemu/qemu_capabilities.c                       |  9 ++
>  src/qemu/qemu_capabilities.h                       |  3 +
>  src/qemu/qemu_command.c                            | 33 ++++++++
>  src/qemu/qemu_driver.c                             |  5 ++
>  src/util/virstoragefile.c                          |  3 +
>  src/util/virstoragefile.h                          |  6 ++
>  tests/qemucapabilitiesdata/caps_2.5.0.x86_64.xml   |  3 +
>  .../caps_2.6.0-gicv2.aarch64.xml                   |  3 +
>  .../caps_2.6.0-gicv3.aarch64.xml                   |  3 +
>  tests/qemucapabilitiesdata/caps_2.6.0.ppc64le.xml  |  3 +
>  tests/qemucapabilitiesdata/caps_2.6.0.x86_64.xml   |  3 +
>  tests/qemucapabilitiesdata/caps_2.7.0.s390x.xml    |  3 +
>  tests/qemucapabilitiesdata/caps_2.7.0.x86_64.xml   |  3 +
>  tests/qemucapabilitiesdata/caps_2.8.0.s390x.xml    |  3 +
>  tests/qemucapabilitiesdata/caps_2.8.0.x86_64.xml   |  3 +
>  tests/qemucapabilitiesdata/caps_2.9.0.ppc64le.xml  |  3 +
>  tests/qemucapabilitiesdata/caps_2.9.0.s390x.xml    |  3 +
>  tests/qemucapabilitiesdata/caps_2.9.0.x86_64.xml   |  3 +
>  .../qemuxml2argv-disk-drive-qcow2-cache.args       | 28 +++++++
>  .../qemuxml2argv-disk-drive-qcow2-cache.xml        | 43 ++++++++++
>  tests/qemuxml2argvtest.c                           |  4 +
>  .../qemuxml2xmlout-disk-drive-qcow2-cache.xml      | 43 ++++++++++
>  tests/qemuxml2xmltest.c                            |  1 +
>  26 files changed, 386 insertions(+), 1 deletion(-)
>  create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-qcow2-cache.args
>  create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-qcow2-cache.xml
>  create mode 100644 tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-drive-qcow2-cache.xml
>