How to reproduce: Re: Only 70% of theoretical peak performance on FreeBSD 8/amd64, Corei7 920

[Adam Vande More]

On Thu, Apr 15, 2010 at 3:54 AM, Andriy Gapon <avg at freebsd.org> wrote:

> This is a good point.
> But on the other hand, it means that our scheduler doesn't do a perfect job
> here.  BTW, I use ULE.
> My observation is that when a number of CPU-intensive long running
> processes is
> less than or equal to number of cores, then the processes tend to stay on
> the
> same cores for a long time.
> But if the number of the processes is greater, then they seem to jump from
> core
> to core a lot.
> But I am not sure what would be an optimal strategy for that case.  If we
> try to
> keep some lucky processes on the same core, then cpu time might be shared
> unfairly.  Shuffling cores provides more fairness, but can hurt total
> performance.
>

Is is possible to add a tunable to the scheduler for it's aggressiveness in
switching cores?

-- 
Adam Vande More