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.
Steven
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