> On Tue, Feb 15, 2011 at 7:45 PM, Chunqiang Tang <ct...@us.ibm.com> wrote: > >> Chunqiang Tang/Watson/IBM wrote on 01/28/2011 05:13:27 PM: > >> As you requested, I set up a wiki page for FVD at > > http://wiki.qemu.org/Features/FVD > >> . It includes a summary of FVD, a detailed specification of FVD, and a > >> comparison of the design and performance of FVD and QED. > > > >> See the figure at http://wiki.qemu.org/Features/FVD/Compare . This > > figure > >> shows that the file creation throughput of NetApp's PostMark benchmark > > under > >> FVD is 74.9% to 215% higher than that under QED. > > File creation on a sparse image is currently limited by the fact that > the QED implementation serializes allocating writes. In earlier QED > patch series I had fine-grained metadata locking so allocating writes > scale better but that lead a regression on another benchmark. I have > this on my todo list. > > This is an implementation-specific limitation and is unrelated to the > file format. It doesn't tell us about a difference between formats.
I agree that a good comparison of the design difference is as important as the quantitative numbers. I previously posted the spec of FVD as well as a comparison of FVD and QED on wiki, http://wiki.qemu.org/Features/FVD . Part of the comparison was also copied in an early email of this thread. I welcome comments and feedback on the design aspect.
