On Wed, Sep 14, 2011 at 10:17 PM, Stefan Hajnoczi <stefa...@gmail.com> wrote: > On Wed, Sep 14, 2011 at 3:42 AM, Zhi Yong Wu <zwu.ker...@gmail.com> wrote: >> Log for bps=((10 * 1024 * 1024)). > > Okay, I think this data shows that I/O limits is too aggressive. > There seems to be some "overhead" amount so the guest is never able to > reach its bps limit: > >> test: (g=0): rw=write, bs=64K-64K/64K-64K, ioengine=libaio, iodepth=1 >> WRITE: io=51,200KB, aggrb=7,073KB/s, minb=7,243KB/s, maxb=7,243KB/s, > >> test: (g=0): rw=write, bs=128K-128K/128K-128K, ioengine=libaio, iodepth=1 >> WRITE: io=51,200KB, aggrb=10,112KB/s, minb=10,355KB/s, > >> test: (g=0): rw=write, bs=256K-256K/256K-256K, ioengine=libaio, iodepth=1 >> WRITE: io=51,200KB, aggrb=8,882KB/s, minb=9,095KB/s, maxb=9,095KB/s, > > bs=128 KB worked nicely. The 64 KB and 256 KB cases don't look so good. > > I worry a little that the benchmark duration is quite short so a > fluctuation would affect the results more than if the benchmark > duration was extended to 30 secs or 1 minute. > > Zhi Yong: Do you get similar results each time you run this benchmark Right > or do they vary by more than +/- 512 KB? If the results are stable The results vary by less than +/-512 KB if i issue multiple times with the same bs value.
> and the benchmark is able to exceed 10 MB/s when running without I/O > throttling, then it's important to figure out why the guest isn't > achieving 10 MB/s. > > Stefan > -- Regards, Zhi Yong Wu
