Re: sched_yield() makes OpenLDAP slow

[Bernardo Innocenti]

Andi Kleen wrote:
> Bernardo Innocenti <bernie@xxxxxxxxxxx> writes:
> 
> It's really more a feature than a bug that it breaks so easily
> because they should be really using futexes instead, which
> have much better behaviour than any sched_yield ever could
> (they will directly wake up another process waiting for the
> lock and avoid the thundering herd for contended locks) 

Actually, I believe they should be using pthread synchronization
primitives instead of relying on Linux-specific functionality.
Glibc already uses futexes internally, so it's almost as efficient.

I've already suggested this to the OpenLDAP people, but with
my limited knowledge of slapd threading requirements, there
may well be a very good reason for busy-waiting with
sched_yield().  Waiting for their answer.

-- 
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

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