Re: (1/4) [PATCH] cpuset -- 2.6.0-test8

[Simon Derr]

Thanks a lot Stephen for your work and for sharing your wisdom with us.

Thank you also William for your remarks.

On Tue, 21 Oct 2003, William Lee Irwin III wrote:
> > +static const int N = (8*sizeof(cpumask_t));
> > +/* this is a cyclic version of next_cpu */
> > +static inline void _next_cpu(const cpumask_t mask, int * index)
> > +{
> > +	for(;;) {
> > +		if (++*index >= N) *index = 0;
> > +		if (cpu_isset(*index, mask)) return;
> > +	}
> > +}
> Best not to insist NR_CPUS % BITS_PER_LONG == 0.
Actually we don't, but you're right, NR_CPUS should definately be used
here.

> > +static void migrate_cpuset_processes(struct cpuset * cs)
> > +	/* This should be a RARE use of the cpusets.
> > +	 * therefore we'll prefer an inefficient operation here
> > +	 * (searching the whole process list)
> > +	 * than adding another list_head in task_t
> > +	 * and locks and list_add for each fork()
> Unfair rwlocks can take boxen out when abused by quadratic algorithms.

I don't see exactly which lock you are talking about here ?
Anyway, the current state of the cpusets is OK for a 'gentle' use. I'm
sure some improvements are needed to protect it from 'evil' users ;-)

	Simon.

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