Messages in this thread | | | From | Steven Cole <> | Date | Tue, 12 Dec 2000 07:49:48 -0700 | Subject | Re: UP 2.2.18 makes kernels 3% faster than UP 2.4.0-test12 |
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Helge Hafting wrote: >Steven Cole wrote: >[...] >>Simple question here, and risking displaying great ignorance: >>Does it make sense to use make -jN where N is much greater than the >>number of CPUs? > >No, but it makes sense to have N at least one more than the number of >cpus, >if you have the memory. This because your processes occationally >will wait for disk io, and this time may then be utilized to >run the "extra" task. But don't overdo it, as you get less disk >cache this way. make -j3 seems to be fastest on my 2-cpu machine >with 128M ram.
Thanks for the answer. That makes a lot of sense. When I get the time, I'll verify that, at least for this fairly narrowly defined task of building a kernel.
In order to minimize external and variable influences on the CPU load, I performed all these tests in console mode not connected to a network. That may have been an unrealistic test, as that is not how I normally do kernel builds. Having to juggle more work, like running X and KDE, could shift the results (2.2.18 vs 2.4.0-test12) around a bit. I'll repeat the tests with a more normal work environment. If anything statistically significant is found, I'll mention it. Thanks to all for their input.
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