Joel Becker <Joel.Becker@oracle.com> wrote:
>
> On Wed, May 07, 2003 at 03:41:50PM -0700, Andrew Morton wrote:
> > > Runs: 1462.17 1005.78 1995.99
> > > ...
> > > This benchmark is sensitive to random system events.
> >
> > You can say that again.
> >
> > We need to understand why there is such variation. If we can do that,
> > then perhaps we can make those 1.0's and 1.5's go away.
>
> Some kernels run very very even. Others do not. I suspect that
> certain kernel behaviors and changes exacerbate the issues.
Correct me if I'm wrong, but this test is largely seek-bound, is it not?
Do you monitor the total CPU utilisation during the run? Is it generally
low? If so then we're seek-bound.
File layout will influence things a lot. Small variations in timing and in
CPU scheduler activity could well cause significant dfifferences in file
layout.
Does the test generate the files on-the-fly, or are they laid out
beforehand?
Is it possible to fully populate the datafiles before the run, with a
single thread of control? That will ensure that each run is working off
the same layout and will give a better basis for comparison.
It will also tell us that some layout tweaks may be needed.
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This archive was generated by hypermail 2b29 : Wed May 07 2003 - 22:00:33 EST