Re: [Qemu-devel] [PATCH 1/3] qcow2: mark the memory as no longer needed after qcow2_cache_empty()

[Max Reitz]

On 18.05.2015 18:48, Alberto Garcia wrote:
> After having emptied the cache, the data in the cache tables is no
> longer useful, so we can tell the kernel that we are done with it. In
> Linux this frees the resources associated with it.
>
> The effect of this can be seen in the block-commit operation: it moves
> data from the top to the base image (and fills both caches), then it
> empties the top image. At this point the data in that cache is no
> longer needed so it's just wasting memory.
>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
>   block/qcow2-cache.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)

Looks good, but by applying the same logic, you could do the same call 
in qcow2_cache_create(). So what about it? :-)

Also note that bdrv_commit() is used only by the HMP commit operation, 
not by QMP commit.

Max