On Mon, Mar 04, 2013 at 02:33:16PM +0000, Dietmar Maurer wrote: > > > > Is it using 64 KB writes and have you tried 256 KB writes? > > > > > > I use a modified 'qemu-img convert' at 64KB block size (I need 64KB for > > backup). > > > > Maybe you'd better use a different output format that doesn't restrict you > > to > > 64k writes. > > The output format is not really the restriction. The problem is that an > additional > IPC layer add overhead, an d I do not want that (because it is totally > unnecessary).
I missed the reason why you cannot increase the block size. At least increase the NBD write size - the VMA process can break up a large write however it likes. Do this and the overhead is divided by 4. Stefan
