Re: [gentoo-amd64] compiling on dual-cores - only 50% usage per cpu

[Bernhard Auzinger <e0026053@student.tuwien.ac.at>]

Am Sonntag 11 November 2007 schrieb Peter Humphrey:
> On Saturday 10 Nov 2007, Bernhard Auzinger wrote:
> > it's not a important question, but has anybody of you noticed when
> > compiling certain packages the load on both cpu's is only about 50%. I
> > have the feeling that it happens with packages that can not be split up
> > into two jobs. But in this case one cpu should be on 100% load and the
> > other one at ~0%. Maybe someone of you has a good explanation for this
> > behaviour.
>
> I posted a question like this a few months ago, and I did a fair amount of
> detective work. Pretty much inconclusive, I'm afraid, but it seemed to be
> due to a motherboard chipset problem. This is a SuperMicro H8DCE; the
> problem only appeared when this replaced a faulty MSI board. I think the
> conversation ran in May, so you should be able to find it in the archive if
> you're interested.
>
> (I'd noticed that the BOINC scheduler was trying to get two processes run
> at full load, one on each CPU, but according to /top/ and /gkrellm/ each
> was getting just 50%, sometimes one on each CPU and sometimes both on the
> same one. And /top/ seemed confused about which CPU was running which
> tasks!)
>
> I don't run BOINC any more, for other reasons, so I haven't run into the
> problem recently. Kernel compilations seem to go OK, so it's all a bit of a
> mystery. I concluded at the time: "I'm left with a vague feeling of
> dissatisfaction from not knowing what's going on, and a suspicion that
> something in the nForce2 chipset doesn't match what the kernel thinks.
> Kernel versions seem not to affect this problem, at least not in the range
> of versions I could find."
>
> --
> Rgds
> Peter.
> Linux Counter 5290, Aug 93

I don't think that it is a motherboard issue because I watched the same 
behaviour not only on my amd64X2 but also at work at a core2-duo and older 
pentium4's.

I will try to find the thread from may.

Thank you.

Bernhard
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