* Jeff Roberson <jroberson@stripped> [07/07/01 15:30]:
> > Jeff Roberson wrote:
> >> Firstly, has anyone examined using pthread standard locks in place of
> >> your home-rolled spinlocks?
> > I assume you mean the InnoDB mutex implementation. I've tested the pthread
> > locks under Solaris 10 and it does help there. I'm interested in your
> > observations and your comments are most welcome.
> I have produced a graph of mysql writes on linux and bsd:
> This is using the sysbench oltp benchmark. I see long periods with no
> disk activity and almost no CPU activity where all mysql threads are
> blocked on a condition variable. This can last for a second or two. Has
> anyone investigated it? Is this an understood problem?
I have a suspicion what may be causing this, but from such a brief
description I can't recognize anything in particular.
Could it be Bug#15815 "Very poor performance with multiple
queries running concurrently"?
Are any DDL statements issued during the load (CREATE/DROP TABLE,
ALTER, FLUSH TABLES, etc?)
> The difference between the blue and green lines on FreeBSD is a patch to
> reduce kernel contention related to fcntl(). However, the most
> significant sources of contention by far are in mysql.
Would be very interesting to know the exact cause.
-- Konstantin Osipov Software Developer, Moscow, Russia
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