Re: [PATCH][RFC] make cpu_sibling_map a cpumask_t

Ingo Molnar
2003-12-08T20:56:37Z

On Mon, 8 Dec 2003, Zwane Mwaikambo wrote:

> > P.S.
> > I have an alternative to Ingo's HT scheduler which basically does
> > the same thing. It is showing a 20% elapsed time improvement with a
> > make -j3 on a 2xP4 Xeon (4 logical CPUs).
>
> -j3 is an odd number, what does -j4, -j8, -j16 look like?

let me guess: -j3 is the one that gives the highest performance boost on a
2-way/4-logical P4 box?

for the SMT/HT scheduler to give any benefits there has to be idle time -
so that SMT decisions actually make a difference.

the higher -j values are only useful to make sure that SMT scheduling does
not introduce regressions - performance should be the same as the pure
SMP/NUMA scheduler's performance.

Ingo