FWIW: Re: SMP and 101% cpu max?

[Linda Walsh <lkml@tlinx.org>]

FYI, running/compiling 2.6.15.5 on a 2x(1GHzxP-III), 1GB
times for "make" -jn bzImage (no modules):
(using export TIMEFORMAT="%2Rsec %2Uusr %2Ssys (%P%% cpu)" )

-j1: 815.80sec 745.64usr 78.74sys (100.00% cpu)
-j2: 445.17sec 778.68usr 86.22sys (100.00% cpu)
-j3: 444.89sec 781.66usr 87.84sys (100.00% cpu)
-j4: 443.08sec 781.81usr 87.97sys (100.00% cpu)
-j5: 445.98sec 782.53usr 87.51sys (100.00% cpu)
-----

I am not seeing the symptom you are describing.  The load
increases proportionately to the 'job limit', but it doesn't
radically change the overall cpu required.  As I have
only 2 cpu's, I can't expect much benefit beyond 2x, with
actual approaching closer to 1.8x.

-l


Jesper Juhl wrote:
> On 3/7/06, Magnus Damm <magnus.damm@gmail.com> wrote:
>   
>> 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.
>