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 |
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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