On 25.11.2013 15:54, Paolo Bonzini wrote:
Il 25/11/2013 14:57, Peter Lieven ha scritto:
since the convert process is basically a sync operation it might
be benificial in some case to change the hardcoded I/O buffer
size to an alternate (greater) value.
Do you really need the extra knob? You can just add to BlockLimits the
optimal transfer length, and use it unconditionally.
If you say patch 5 and 3 are ok. What could be done is to remove
this knob and increase the iobuf_size to cluster_size if cluster_size
is greater. I do not want to increase the default iobuf size to anything
greater than 2MB. I do not know why this was choosen, but maybe
there was a reason for it.
The storages we use here have a very strange page size of 15MB.
If I sent aligned 15MB chunks the performace is about +50% compared
to the original qemu-img.
Peter
