[libvirt] [PATCH 0/2] speed up qemu domain save by increasing dd blocksize

[Laine Stump]

These two patches are posted together because applying the 2nd exposes
the bug fixed by the first.

Here are the results of tests I made with various block sizes before
deciding the 1MB really was the best balance (all tests were done on a
paused 512MB domain, saving to local disk on a Lenovo T61 laptop)

BS      M:SS   save image size
-----   ----   ---------------
2048K - 0:56   476135451
1024K - 0:56   475090953
 512k - 1:02   474564173
 256k - 1:10   474303797
 128k - 1:25   474176859
 512  - 3:47   474085423 - the original

I didn't bother testing sizes between 512 and 128k, as there was still
significant improvement from 128k to 256k.