Bug description: As reported here:
http://www.redhat.com/archives/libvir-list/2009-December/msg00203.html
"virsh save" is very slow - it writes the image at around 1MB/sec on
my test system. (I think I saw a bug report for this issue on Fedora's
bugzilla, but I can't find it now...)
Here's the Fedora bug:
https://bugzilla.redhat.com/show_bug.cgi?id=599091
Note that I've already pushed a patch upstream that fixes the problem
(reduces save time for a 512MB guest from 3:47 to 0:56), and eric Blake
has posted a more refined patch that wastes less space by invoking dd
twice (once for libvirt's header, and again for the image) - that hasn't
been pushed yet, but will almost definitely supercede my patch before
the libvirt-0.8.2 release.
