Fine-grained locking for POSIX local sockets (UNIX domain sockets)

Sven Petai hadara at
Sun May 7 20:27:43 UTC 2006

On Sunday 07 May 2006 22:16, you wrote:
> On Sun, May 07, 2006 at 10:00:41PM +0300, Sven Petai wrote:
> > The results in my mail were mean values over 2 runs,
> > only once did I see really huge (more than 10%) differences between
> > several subsequent runs with same settings, this case was clearly
> > mentioned in the results.
> FYI, 2 is not really enough, you should do at least 10 repetitions of
> each test to reduce variance (which can be a lot, despite what you
> saw!) and so that differences between them can be accurately
> estimated.  Ministat is really helpful for this.

I'm well aware that 2 is not enough for quality measurements and
I certainly would have liked to do more repetitions, but I was running against 
a clock - this machine might be shipped out to client any
time and I wanted to test several combinations of OS [fbsd 6, fbsd current, 
current + watsons patch, linux] with different threading library and 
scheduler combinations at different thread counts and nice values. 
This creates nice combinatorial explosion.

Even a single run on one OS ver + one of the schedulers with 2 repetitions of 
each test takes about 2 hours, so I had to make some compromises.

But i believe the trends are clear enough from these results and while I 
certainly can't say anything about <~5% performance changes what we see are
consistent trends and 20%+ performance differences.

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