linux-kernel - Question about setting affinity in 2.4

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Message-ID: <2fe399760702181802q39e75b42iea7f80124506f169@mail.gmail.com>
Date:	Sun, 18 Feb 2007 18:02:17 -0800
From:	"Phy Prabab" <phyprabab@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Question about setting affinity in 2.4

Hello everyone,

I am trying to set affinity on a program to make sure I can get the
best use of the cache as possible and to eliminate as much noise as
possible with running my program.  I have tried unsuccessfully to set
affinity using sched_set/getaffinity and the CPU_SET macros.  In
particular, I can not seem to get the process to use affinity I
specify as in:

int main () {
  cpu_set_t mask;
  cpu_set_t setmask;
  long long x;
  double foo;
  printf("Mask set to %08lx\n", sched_getaffinity(0, &mask));
  CPU_SET(1, &mask);
  if (sched_setaffinity(0, &mask) == -1) {
     printf("error setting affinity.");
  }

  printf("Mask is reset to %08lx\n", sched_getaffinity(0, &mask));
  // do some long lasting calculations ....

  return;
}

No mater what I do, the process is never bond to the processor in
question as exposed by this little appy and by cat /proc/<pid>/cpu.
Is this just impossible to do?

Ah, the kernel I am using is RH 2.4.21-37.ELsmp.

TIA!
Phy
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