Re: [patch] O(1) scheduler, -D1, 2.5.2-pre9, 2.4.17

Jeffrey W. Baker
2002-01-09T06:42:04Z

On Wed, 9 Jan 2002, Brian wrote:

> Can this be correct?
>
> Intuitively, I would expect several CPUs hammering away at the compile to
> finish faster than one. Given these numbers, I would have to conclude
> that is not just wrong, but absolutely wrong. Compile time increases
> linearly with the number of jobs, regardless of the number of CPUs.
>
> What would cause this? Severe memory bottlenecks?

Mike ran make -j 8 which means 8 compiler processes for each "# Makes" in
the table. Thus, the first row has 8 parallel processes on a 2-way and
the last row has 48 processes on an 8-way. The best ratio is 8 processes
on an 8-way which not incidentally also has the lowest time: 57 seconds.

-jwb

>
> -- Brian
>
> On Tuesday 08 January 2002 10:39 pm, Mike Kravetz wrote:
> > --------------------------------------------------------------------
> > mkbench - Time how long it takes to compile the kernel.
> > We use 'make -j 8' and increase the number of makes run
> > in parallel. Result is average build time in seconds.
> > Lower is better.
> > --------------------------------------------------------------------
> > # CPUs # Makes Vanilla O(1) haMQ
> > --------------------------------------------------------------------
> > 2 1 188 192 184
> > 2 2 366 372 362
> > 2 4 730 742 600
> > 2 6 1096 1112 853
> > 4 1 102 101 95
> > 4 2 196 198 186
> > 4 4 384 386 374
> > 4 6 576 579 487
> > 8 1 58 57 58
> > 8 2 109 108 105
> > 8 4 209 213 186
> > 8 6 309 312 280
> -
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