lkml.org 
[lkml]   [2010]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [Xen-devel] domU is causing misaligned disk writes
    On Tue, Apr 20, 2010 at 10:54:42PM +0300, Pasi Kärkkäinen spake thusly:
    > Please try with "bs=1024k" and maybe with "bs=64k" aswell.
    >
    > 4k blocksize transfer will always be slower in domU than in dom0
    > since virtual disk abstraction makes some overhead, which is more
    > visible with small blocksizes.

    But overhead in domU wouldn't be causing all of these reads. I am
    doing a test with bs=64k now:

    Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz
    avgqu-sz await svctm %util
    sda 0.00 3258.20 964.00 54.00 3903.20 13652.80
    34.49 2.75 2.71 0.68 68.88
    sdb 0.00 3270.20 974.80 54.00 3940.80 13710.40
    34.31 2.42 2.38 0.55 56.22

    > So the speed is the same to the partitioned disk than to the raw disk?
    > What disk backend are you using in dom0? phy:? tap:aio: ?

    Yes.

    I am using phy: disk backend. Should I be using something else?

    --
    Tracy Reed
    http://tracyreed.org
    [unhandled content-type:application/pgp-signature]
    \
     
     \ /
      Last update: 2010-04-20 22:05    [W:0.018 / U:1.716 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site