Messages in this thread | | | Subject | Re: [PATCH [RT] 10/14] adjust pi_lock usage in wakeup | From | "Peter W. Morreale" <> | Date | Thu, 21 Feb 2008 10:09:04 -0700 |
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On Thu, 2008-02-21 at 11:48 -0500, Steven Rostedt wrote: > On Thu, 21 Feb 2008, Gregory Haskins wrote: > > > From: Peter W.Morreale <pmorreale@novell.com> > > > > In wakeup_next_waiter(), we take the pi_lock, and then find out whether > > we have another waiter to add to the pending owner. We can reduce > > contention on the pi_lock for the pending owner if we first obtain the > > pointer to the next waiter outside of the pi_lock. > > > > This patch adds a measureable increase in throughput. > > I see how this may decrease contention (slightly less time in holding the > pi_lock). But, please, when stating something like: "adds a measurable > increase in throughput", show the benchmark numbers. > > -- Steve >
Approximately 3% to the dbench benchmark we used.
My "standard" sanity check was to mount a ramfs filesystem and execute:
dbench -t 10 30
five times and generate an average from the reported "Throughput" numbers displayed by the runs.
dbench was chosen merely because of the contention on dcache_lock.
Best, -PWM
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