On Fri, Jan 19, 2001 at 02:08:52AM +0100, Andi Kleen wrote:
> On Thu, Jan 18, 2001 at 08:00:16PM -0500, Mark Hahn wrote:
> > > > microseconds/yield
> > > > # threads 2.2.16-22 2.4 2.4-multi-queue
> > > > ------------ --------- -------- ---------------
> > > > 16 18.740 4.603 1.455
> > >
> > > I remeber the O(1) scheduler from Davide Libenzi was beating the mainline O(N)
> >
> > isn't the normal case (as in "The Right Case to optimize")
> > where there are close to zero runnable tasks? what realistic/sane
> > scenarios have very large numbers of spinning threads? all server
> > situations I can think of do not. not volanomark -loopback, surely!
>
> I think the main point of Mike's patch is decreasing locking and cache line
> bouncing overhead of multi cpu scheduling, not optimizing lots of runnable tasks.
>
>
> -Andi
Andi is correct. Although the results I posted may seem to indicate
we are concentrating on high thread counts, this is really secondary
to reducing lock contention within the scheduler. A co-worker down
the hall just ran pgbench (a postgresql db) benchmark and saw
contention on the runqueue lock at 57%. Now, I know nothing about this
benchmark, but it will be interesting to see what happens after
applying my patch.
--
Mike Kravetz [EMAIL PROTECTED]
IBM Linux Technology Center
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