From: Steven Rostedt
Date: Wed May 21 2008 - 08:47:42 EST

On Wed, 21 May 2008, Mike Galbraith wrote:
> On Tue, 2008-05-20 at 00:46 -0400, Steven Rostedt wrote:
> > We are pleased to announce the tree, which can be
> > downloaded from the location:
> >
> >
> I ran mysql+oltp (ro) on and 2.6.25-rt2 to compare
> throughput to their parent trees, and ended up with strange (and
> verified) looking performance curves for both trees. The changes in
> and cured the primary oddities.

The difference between 24-rt7 and 24-rt8 as well as with 25-rt2 and 25-rt3
is the deserialization of rwlocks. The rt patch as always serialized
readers to allow for priority inheritance with rwlocks. I wrote a patch to
break that and allow for multiple readers and still keep the priority

Your test probably had a bottle neck on a rwlock (same for rwsems)
somewhere that the new code solved.

-- Steve
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