Multi-processor information

andrew at bishop.dropbear.id.au andrew at bishop.dropbear.id.au
Sun Jan 20 15:50:31 EST 2002


On Sun, 20 Jan 2002, Daniel McNamara wrote:

[...]
> I understand that to take advantage of the dual processors my kernel will
> need multi-processor support built in. What I don't fully understand is how
> applications will take advantage of them. Do they just pass calls to the
> kernel and it takes care of it? Or does the program itself also have to be
> compiled with support for multi-processing?

If the program in question runs multiple threads, then linux will be able
to run 2 of them at once.  If it only has one thread, then it will only be
a bit faster (as linux will be able to put other jobs onto the other cpu,
so it doesn't get interrupted).  In the case of apache, it runs multiple
threads (to handle multiple simultaneous conenctions), so it will benefit
from having 2 cpus (2 threads can be running at once).  You don't need to
recompile or anything.

HTH,

Andrew





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