On Tue, Apr 28, 2015 at 10:46:59AM +0300, Denis V. Lunev wrote: > Plain image expansion spends a lot of time to update image file size. > This seriously affects the performance. The following simple test > qemu_img create -f parallels -o cluster_size=64k ./1.hds 64G > qemu_io -n -c "write -P 0x11 0 1024M" ./1.hds > could be improved if the format driver will pre-allocate some space > in the image file with a reasonable chunk. > > This patch preallocates 128 Mb using bdrv_write_zeroes, which should > normally use fallocate() call inside. Fallback to older truncate() > could be used as a fallback using image open options thanks to the > previous patch. > > The benefit is around 15%. > > Signed-off-by: Denis V. Lunev <d...@openvz.org> > Reviewed-by: Roman Karan <rka...@parallels.com>
s/Karan/Kagan/ > CC: Kevin Wolf <kw...@redhat.com> > CC: Stefan Hajnoczi <stefa...@redhat.com> > --- > block/parallels.c | 42 ++++++++++++++++++++++++++++++++---------- > 1 file changed, 32 insertions(+), 10 deletions(-) Roman.
