Re: [Qemu-devel] [PATCH 0/2] improve qemu-img conversion performance

[Sage Weil]

On Fri, 9 Sep 2011, Kevin Wolf wrote:
> Am 08.09.2011 18:36, schrieb Sage Weil:
> > On Thu, 8 Sep 2011, Kevin Wolf wrote:
> >> Am 08.09.2011 01:06, schrieb Yehuda Sadeh:
> >>> The following set of patches improve the qemu-img conversion process
> >>> performance. When using a higher latency backend, small writes have a
> >>> severe impact on the time it takes to do image conversion. 
> >>> We switch to using async writes, and we avoid splitting writes due to
> >>> holes when the holes are small enough.
> >>>
> >>> Yehuda Sadeh (2):
> >>>   qemu-img: async write to block device when converting image
> >>>   qemu-img: don't skip writing small holes
> >>>
> >>>  qemu-img.c |   34 +++++++++++++++++++++++++++-------
> >>>  1 files changed, 27 insertions(+), 7 deletions(-)
> >>>
> >>
> >> This doesn't seem to be against git master or the block tree. Please 
> >> rebase.
> >>
> >> I think that commit a22f123c may obsolete your patch 2/2.
> > 
> > With git.kernel.org down, where should I be looking for the latest 
> > upstream?
> 
> qemu has never been on kernel.org. The interesting repositories for you are:
> 
> * Upstream: git://git.qemu.org/qemu.git master
> * Block development branch: git://repo.or.cz/qemu/kevin.git block

Oh right.  I've been working from qemu-kvm.git.  

I've done some (still minimal) testing, and it looks like the combination 
of a22f123c and the new writeback/flush stuff in librbd gets the same 
result as doing async io explicitly from qemu-img.c.  Want to take a look, 
Yehuda?  It still defaults to off, so you'll need to add 
rbd_writeback_window=8000000 or similar to the rbd device string.

Thanks!
sage