Re: Auto-Adaptive scheduler - Final chapter ( the numbers ) ...

Davide Libenzi (davidel@maticad.it)
Thu, 27 Jan 2000 18:18:06 +0100

Thursday, January 27, 2000 6:10 PM
Horst von Brand <vonbrand@pincoya.inf.utfsm.cl> wrote :
> As was said here time and again: This is ridiculously unrealistic. Your
> benchmark plus whatever scheduler you use fits in the smallest cache. Use
> some code that is some 2 or 3Kb at least between schedules, and run
> _different_ code each time. I'd bet you see quite different numbers that
way.

These are my words in Larry answer :

<DONTSPLITTHIS>
This is a pure switching time test.
It is a _real_ switching test, that can be used to test switching times
under _certain_
RQ loads :

vmstat of a "lat_ctx -s 0 20" give no more than 5-6 tasks in RQ

vmstat of a "threads 20 xx" give always an RQ = 20 ( with no need of cost
compensation )

Now, as even my sister ( that works in business ) can realize this code is
stored entirely in cache, and the write to the counter is onto the process
stack.
I _want_ this behaviour coz I _want_ a measure of clean switching times by
keeping
cache issues ot of the test.
</DONTSPLITTHIS>

Anyway adding a cache footprint into the two cases will add a constant term
that minimize
even more the percent result.

Davide.

--
All this stuff is IMVHO






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