Messages in this thread | | | Date | Tue, 21 Feb 2006 22:51:24 +0100 | From | "Jesper Juhl" <> | Subject | Re: make -j with j <= 4 seems to only load a single CPU core |
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On 2/21/06, Paul Fulghum <paulkf@microgate.com> wrote: > On Tue, 2006-02-21 at 22:10 +0100, Jesper Juhl wrote: > > > I should probably mention that the kernel I'm currently running and > > observing this behaviour with is 2.6.16-rc4-mm1. > ... > > > I find this quite strange since anything from 'make -j 2' and up > > > should be able to keep both cores resonably busy, but there seems to > > > be a huge difference between j <= 4 and j > 4. > > I've seen the same thing (on Athlon 64x2 64 bit) > but was not sure if it was a problem. > > The break point for me seems to be between -j 2 and -j 3 > -j 2 = serialized (or the appearance of) > -j 3 = both cores mostly busy > > I'm pretty sure with an earlier 2.6 kernel source (but same environment) > I did not see this. I'll start back tracking to earlier kernels > to see if I can identify when this started. >
I know positively that I've seen this with previous 2.6.16-<something> kernels, but not sure which ones exactely. I just dismissed it as something that would probably be fixed soon and then today when I build a few test kernels I noticed it again and thought "ohh, so it didn't get fixed, better report it".
I don't recall seeing it with 2.6.15 and earlier kernels, but I'm not at all sure - especially since I only got this Athlon X2 box recently and the first kernels I ever ran on it were 2.6.15-<something>.
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