Messages in this thread | | | Date | Tue, 21 Oct 2003 17:08:08 -0700 | From | William Lee Irwin III <> | Subject | Re: (1/4) [PATCH] cpuset -- 2.6.0-test8 |
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On Tue, Oct 21, 2003 at 04:20:19PM -0700, Stephen Hemminger wrote: > +static const int N = (8*sizeof(cpumask_t)); > +/* mask must NOT be ZERO ! */ > +/* 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.
On Tue, Oct 21, 2003 at 04:20:19PM -0700, Stephen Hemminger wrote: > +/* When a cpuset with attached processes is being realloc'ed CPUs > + * update the processes' masks and migrate them > + */ > +static void migrate_cpuset_processes(struct cpuset * cs) > +{ > + struct task_struct *g, *p; > + /* 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.
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