[patch v3] manual: add remaining CPU_* macros

[Collin Funk]

DJ Delorie <dj@redhat.com> writes:

> +Here's an example of how to use most of the above to limit the number
> +of CPUs a process runs on, not including error handling or good logic
> +on CPU choices:
> +
> +@example
> +#define _GNU_SOURCE
> +#include <sched.h>
> +#include <sys/sysinfo.h>
> +#include <unistd.h>
> +void limit_cpus (void)
> +@{
> +  unsigned int mycpu;
> +  size_t nproc, cssz, cpu;
> +  cpu_set_t *cs;
> +  getcpu (&mycpu, NULL);
> +  nproc = get_nprocs_conf ();
> +  cssz = CPU_ALLOC_SIZE (nproc);
> +  cs = CPU_ALLOC (nproc);
> +  sched_getaffinity (0, cssz, cs);
> +  if (CPU_COUNT_S (cssz, cs) > nproc / 2)
> +    @{
> +      for (cpu = nproc / 2; cpu < nproc; cpu ++)
> +        if (cpu != mycpu)
> +          CPU_CLR_S (cpu, cssz, cs);
> +      sched_setaffinity (0, cssz, cs);
> +    @}
> +  CPU_FREE (cs);
> +@}
> +@end example

Thanks to Mark for pointing out the issues in the original example. I
learned my lesson and compiled it this time and checked the affinity
before and after. It worked as expected and halved the affinity.

One minor request, though. Can we change:

    void limit_cpus (void)

to:

    void
    limit_cpus (void)

It is more consistent with the rest of the examples in the manual.

Otherwise, the patch is good to me.

Reviewed-by: Collin Funk <collin.funk1@gmail.com>

Collin