Messages in this thread | | | Subject | Re: [PATCH v8 7/8] mm: only IPI CPUs to drain local pages if they exist | Date | Wed, 08 Feb 2012 10:33:13 +0100 | From | "Michal Nazarewicz" <> |
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On Sun, 05 Feb 2012 14:48:41 +0100, Gilad Ben-Yossef <gilad@benyossef.com> wrote: > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d2186ec..3ff5aff 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1161,11 +1161,46 @@ void drain_local_pages(void *arg) > } > /* > - * Spill all the per-cpu pages from all CPUs back into the buddy allocator > + * Spill all the per-cpu pages from all CPUs back into the buddy allocator. > + * > + * Note that this code is protected against sending an IPI to an offline > + * CPU but does not guarantee sending an IPI to newly hotplugged CPUs: > + * on_each_cpu_mask() blocks hotplug and won't talk to offlined CPUs but > + * nothing keeps CPUs from showing up after we populated the cpumask and > + * before the call to on_each_cpu_mask(). > */ > void drain_all_pages(void) > { > - on_each_cpu(drain_local_pages, NULL, 1); > + int cpu; > + struct per_cpu_pageset *pcp; > + struct zone *zone; > + > + /* Allocate in the BSS so we wont require allocation in > + * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y > + */
If you are going to send next iteration, this comment should have “/*” on its own line just like comment below.
> + static cpumask_t cpus_with_pcps; > + > + /* > + * We don't care about racing with CPU hotplug event > + * as offline notification will cause the notified > + * cpu to drain that CPU pcps and on_each_cpu_mask > + * disables preemption as part of its processing > + */ > + for_each_online_cpu(cpu) { > + bool has_pcps = false; > + for_each_populated_zone(zone) { > + pcp = per_cpu_ptr(zone->pageset, cpu); > + if (pcp->pcp.count) { > + has_pcps = true; > + break; > + } > + } > + if (has_pcps) > + cpumask_set_cpu(cpu, &cpus_with_pcps); > + else > + cpumask_clear_cpu(cpu, &cpus_with_pcps); > + } > + on_each_cpu_mask(&cpus_with_pcps, drain_local_pages, NULL, 1); > } > #ifdef CONFIG_HIBERNATION
-- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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