Re: SMP and 101% cpu max?

["Jesper Juhl" <jesper.juhl@gmail.com>]

On 3/7/06, Magnus Damm <magnus.damm@gmail.com> wrote:
> Hi guys,
>
> I'm doing some memory related hacking, and part of that is testing the
> current behaviour of the Linux VM. This testing involves running some
> simple tests (building the linux kernel is one of the tests) while
> varying the amount of RAM available to the kernel.
>
> I've tested memory configurations of 64MB, 128MB and 256MB on a Dual
> PIII machine. The tested kernel is 2.6.16-rc5, and user space is based
> on debian-3.1. I run 5 tests per memory configuration, and the machine
> is rebooted between each test.
>
> Problem:
>
> With 128MB and 256MB configurations, a majority of the tests never
> make it over 101% CPU usage when I run "make -j 2 bzImage", building a
> allnoconfig kernel. With 64MB memory, everything seems to be working
> as expected. Also, running "make bzImage" works as expected too.
>
Hmm, I wonder if it's related to the problem I reported here :
http://lkml.org/lkml/2006/2/28/219
Where I need to run make -j 5 or higher to load both cores of my Athlon X2.

--
Jesper Juhl <jesper.juhl@gmail.com>
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