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    SubjectRe: [PATCH v4 4/5] slub: Only IPI CPUs that have per cpu obj to flush
    On 11/23/2011 08:23 AM, Pekka Enberg wrote:
    > On Tue, 22 Nov 2011, Gilad Ben-Yossef wrote:
    >> static void flush_all(struct kmem_cache *s)
    >> {
    >> - on_each_cpu(flush_cpu_slab, s, 1);
    >> + cpumask_var_t cpus;
    >> + struct kmem_cache_cpu *c;
    >> + int cpu;
    >> +
    >> + if (likely(zalloc_cpumask_var(&cpus, GFP_ATOMIC))) {
    >
    > __GFP_NOWARN too maybe?
    >
    >> + for_each_online_cpu(cpu) {
    >> + c = per_cpu_ptr(s->cpu_slab, cpu);
    >> + if (c->page)
    >> + cpumask_set_cpu(cpu, cpus);
    >> + }
    >> + on_each_cpu_mask(cpus, flush_cpu_slab, s, 1);
    >> + free_cpumask_var(cpus);
    >> + } else
    >> + on_each_cpu(flush_cpu_slab, s, 1);
    >> }
    >

    Since this seems to be a common pattern, how about:

    zalloc_cpumask_var_or_all_online_cpus(&cpus, GFTP_ATOMIC);
    ...
    free_cpumask_var(cpus);

    The long-named function at the top of the block either returns a newly
    allocated zeroed cpumask, or a static cpumask with all online cpus set.
    The code in the middle is only allowed to set bits in the cpumask
    (should be the common usage). free_cpumask_var() needs to check whether
    the freed object is the static variable.

    --
    error compiling committee.c: too many arguments to function



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