Re: WimMark I report for 2.5.69

[Andrew Morton]

Joel Becker <[e-mail]> 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.