lkml.org 
[lkml]   [2009]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: ext3 IO latency measurements (was: Linux 2.6.29)
    On Thu, 26 Mar 2009 15:36:18 +0100
    Jens Axboe <jens.axboe@oracle.com> wrote:

    > On Thu, Mar 26 2009, Arjan van de Ven wrote:
    > > On Thu, 26 Mar 2009 12:08:15 +0100
    > > Jens Axboe <jens.axboe@oracle.com> wrote:
    > > >
    > > > Did you capture the trace of the long delays in the read test
    > > > case? It can be two things, at least. One is that each little
    > > > read takes much longer than it should, the other is that we get
    > > > stuck waiting on a dirty page and hence that slows down the reads
    > > > a lot.
    > > >
    > >
    > > would be interesting to run latencytop during such runs...
    >
    > Things just drown in the noise in there sometimes, is my experience...
    > And disappear. Perhaps I'm just not very good at reading the output,
    > but it was never very useful for me. I know, not a very useful
    > complaint, I'll try and use it again and come up with something more
    > productive :-)
    >
    > But in this case, I bet it's also the atime updates. If Ingo turned
    > those off, the read results would likely be a lot better (and
    > consistent).

    latencytop does identify those for sure.
    >


    --
    Arjan van de Ven Intel Open Source Technology Centre
    For development, discussion and tips for power savings,
    visit http://www.lesswatts.org


    \
     
     \ /
      Last update: 2009-03-26 15:53    [W:0.021 / U:209.540 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site