Re: [Qemu-devel] [PATCH 0/5] qcow2: Discard freed clusters

[Kevin Wolf]

Am 18.06.2013 um 05:03 hat Wenchao Xia geschrieben:
> Hi, Kevin
>   In normal case, qcow2 is based on raw-posix file which don't support
> discard operation

It does, see raw_aio_discard().

> , so this serial doesn't change much in this case,
> still real space is not freed in snapshot delete, and it completes
> fast. Instead, tt affects the case that some protocol below support
> discard, so delete will be more clean but slower in that case. Is this
> true? Maybe add this in commit message?

Yes, it becomes a little bit slower, but not much in my tests.

Kevin