Re: Scheduling tests on IPC methods, fc6, sd0.48, cfs12

Bill Davidsen
2007-05-22T22:34:44Z

William Lee Irwin III wrote:
> On Thu, May 17, 2007 at 07:26:38PM -0400, Bill Davidsen wrote:
>> I have posted the results of my initial testing, measuring IPC rates
>> using various schedulers under no load, limited nice load, and heavy
>> load at nice 0.
>> http://www.tmr.com/~davidsen/ctxbench_testing.html
>
> Kernel compiles are not how to stress these. The way to stress them is
> to have multiple simultaneous independent chains of communicators and
> deeper chains of communicators.
>
> Kernel compiles are little but background cpu/memory load for these
> sorts of tests.

Just so. What is being quantified is the rate of slowdown due to
external load. I would hope that each IPC method would slow by some
similar factor.

> ... Something expected to have some sort of mutual
> interference depending on quality of implementation would be a better
> sort of competing load, one vastly more reflective of real workloads.
> For instance, another set of processes communicating using the same
> primitive.
>
The original intent was purely to measure IPC speed under no load
conditions, since fairness is in vogue I also attempted to look for
surprising behavior. Corresponding values under equal load may be useful
in relation to one another, but this isn't (and hopefully doesn't claim
to be) a benchmark. It may or may not be useful viewed in that light,
but that's not the target.

> Perhaps best of all would be a macrobenchmark utilizing a variety of
> the primitives under consideration. Unsurprisingly, major commercial
> databases do so for major benchmarks.
>
And that's a very good point, either multiple copies or more forked
processes might be useful, and I do intend to add threaded tests on the
next upgrade, but perhaps a whole new code might be better for
generating the load you suggest.

--
Bill Davidsen <davidsen@tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot