Re: [patch 2/3] knfsd: avoid overloading the CPU scheduler with enormous load averages

[Greg Banks <gnb@melbourne.sgi.com>]

Peter Staubach wrote:
> Greg Banks wrote:
>> [...]
>> Testing was on a 4 CPU 4 NIC Altix using 4 IRIX clients, each with 16
>> synthetic client threads simulating an rsync (i.e. recursive directory
>> listing) workload[...]
>>
>> Profiling showed schedule() taking 6.7% of every CPU, and __wake_up()
>> taking 5.2%.  This patch drops those contributions to 3.0% and 2.2%.
>> Load average was over 120 before the patch, and 20.9 after.
>> [...]
>
> Have you measured the impact of these changes for something
> like SpecSFS?

Not individually.  This patch was part of some work I did in late
2005/early 2006 which was aimed at improving NFS server performance in
general.  I do know that the server's SpecSFS numbers jumped by a factor
of somewhere over 2x, from embarrassingly bad to publishable, when
SpecSFS was re-run after that work.  However at the time I did not have
the ability to run SpecSFS myself, it was run by a separate group of
people who had dedicated hardware and experience.  So I can't tell what
contribution this particular patch made to the overall SpecSFS
improvements.  Sorry.

-- 
Greg Banks, P.Engineer, SGI Australian Software Group.
the brightly coloured sporks of revolution.
I don't speak for SGI.