RE: [PATCH] Hook up getcpu system call for IA64

From: Luck, Tony <>
Date: 2007-02-07 08:32:36
> > getcpu system call returns cpu# and node# on which this system call
> > and its caller are running. This patch hooks up its implementation on
> > IA64.
> I know it's trivial to wire up sys_getcpu, but please take this seriously,
> it should be implemented as assembly fsys call.

We did look at whether it was worth doing as a fast syscall.

How often will applications call getcpu() ... I hope that they aren't doing
it hundreds of thousands of times per second (scheduler won't re-assign to
a different cpu more often than every few milli-seconds, so it is pointless
to call that often).

"Slow" syscall is ~1.5us ... which should be in the noise for what I think
is the fastest rate at which applications may call it.

Do you have some example application scenarios where you believe the
rate will be high enough to make a difference?

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Received on Wed Feb 07 08:33:22 2007

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