Re: Updated Linux kernel preemption patches

[Robert Love <rml@tech9.net>]

On Sun, 2001-08-26 at 23:06, Daniel Phillips wrote:
> Congratulations on showing evidence that preemption can improve performance 
> under some loads, especially the all-important kernel compile.  Don't be too 
> worried about the dbench 1 results, dbench can vary by a factor of 2 
> depending on the alignment of the planets (ask Tridge).  Try something more 
> stable like bonnie.

I would be happy to run some other tests.  I was happy to see the kernel
compile prove faster, and I fully expected the dbench 16 results to show
an improvement.  But, while I assumed dbench 1 may show a degradation in
performance, I was surprised it was so high.

My main goal in updating Nigel's patches to recent kernels was to
accomplish just this: get some more data points, some more benchmarks,
and more eyes on the code and systems running the patch.

I am not an audio guy or otherwise in need of a lower-latency system,
but the possibility for an overall improvement in the kernel (even at
the expense of some cases) is worthwhile, to me.

> The theory goes that preemption improves performance by cutting down the time 
> between IO completion and user task resume, with only a small cost in extra 
> locking.  It would be nice to see profiling statistics to support this idea.

Anyone running the patch want to profile some situations and reach some
conclusions?

-- 
Robert M. Love
rml at ufl.edu
rml at tech9.net