On Thu, Sep 30, 2010 at 1:50 AM, Venkateswararao Jujjuri (JV) <jv...@linux.vnet.ibm.com> wrote: > Code: Mainline QEMU (git://git.qemu.org/qemu.git) > Machine: LS21 blade. > Disk: Local disk through VirtIO. > Did not select any cache option. Defaulting to writethrough. > > Command tested: > 3 parallel instances of : dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000 > > QEMU with smp=1 > 19.3 MB/s + 19.2 MB/s + 18.6 MB/s = 57.1 MB/s > > QEMU with smp=4 > 15.3 MB/s + 14.1 MB/s + 13.6 MB/s = 43.0 MB/s > > Is this expected?
Did you configure with --enable-io-thread? Also, try using dd oflag=direct to eliminate effects introduced by the guest page cache and really hit the disk. Stefan
