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SubjectRe: O(1) scheduler gives big boost to tbench 192
On Wed, 2002-05-08 at 08:34, Jussi Laako wrote:

> Mike Kravetz wrote:
> >
> > I'd really like to know if there are any real workloads that
> > benefited from this feature, rather than just some benchmark.
> Maybe this is the reason why O(1) scheduler has big latencies with
> pthread_cond_*() functions which original scheduler doesn't have?
> I think I tracked the problem down to try_to_wake_up(), but I was unable to
> fix it.

Ah this could be the same case. I just looked into the definition of
the conditional variable pthread stuff and it looks like it _could_ be
implemented using pipes but I do not see why it would per se. If it
does not use pipes, then this sync issue is not at hand (only the pipe
code passed 1 for the sync flag).

If it does not use pipes, we could have another problem - but I doubt
it. Maybe the benchmark is just another case where it shows worse
performance due to some attribute of the scheduler or load balancer?

Robert Love

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