+static int __devinit zone_batchsize(struct zone *zone)
+{
+ int batch;
+
+ /*
+ * The per-cpu-pages pools are set to around 1000th of the
+ * size of the zone. But no more than 1/4 of a meg - there's
+ * no point in going beyond the size of L2 cache.
+ *
+ * OK, so we don't know how big the cache is. So guess.
+ */
+ batch = zone->present_pages / 1024;
+ if (batch * PAGE_SIZE > 256 * 1024)
+ batch = (256 * 1024) / PAGE_SIZE;
+ batch /= 4; /* We effectively *= 4 below */
+ if (batch < 1)
+ batch = 1;
+
+ /*
+ * Clamp the batch to a 2^n - 1 value. Having a power
+ * of 2 value was found to be more likely to have
+ * suboptimal cache aliasing properties in some cases.
+ *
+ * For example if 2 tasks are alternately allocating
+ * batches of pages, one task can end up with a lot
+ * of pages of one half of the possible page colors
+ * and the other with pages of the other colors.
+ */
+ batch = (1 << fls(batch + batch/2)) - 1;
+ return batch;
+}
+
+inline void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
+{
+ struct per_cpu_pages *pcp;
+
+ pcp = &p->pcp[0]; /* hot */
+ pcp->count = 0;
+ pcp->low = 2 * batch;
+ pcp->high = 6 * batch;
+ pcp->batch = max(1UL, 1 * batch);
+ INIT_LIST_HEAD(&pcp->list);
+
+ pcp = &p->pcp[1]; /* cold*/
+ pcp->count = 0;
+ pcp->low = 0;
+ pcp->high = 2 * batch;
+ pcp->batch = max(1UL, 1 * batch);
+ INIT_LIST_HEAD(&pcp->list);
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * Boot pageset table. One per cpu which is going to be used for all
+ * zones and all nodes. The parameters will be set in such a way
+ * that an item put on a list will immediately be handed over to
+ * the buddy list. This is safe since pageset manipulation is done
+ * with interrupts disabled.
+ *
+ * Some NUMA counter updates may also be caught by the boot pagesets.
+ *
+ * The boot_pagesets must be kept even after bootup is complete for
+ * unused processors and/or zones. They do play a role for bootstrapping
+ * hotplugged processors.
+ *
+ * zoneinfo_show() and maybe other functions do
+ * not check if the processor is online before following the pageset pointer.
+ * Other parts of the kernel may not check if the zone is available.
+ */
+static struct per_cpu_pageset
+ boot_pageset[NR_CPUS];
+
+/*
+ * Dynamically allocate memory for the
+ * per cpu pageset array in struct zone.
+ */
+static int __devinit process_zones(int cpu)
+{
+ struct zone *zone, *dzone;
+
+ for_each_zone(zone) {
+
+ zone->pageset[cpu] = kmalloc_node(sizeof(struct per_cpu_pageset),
+ GFP_KERNEL, cpu_to_node(cpu));
+ if (!zone->pageset[cpu])
+ goto bad;
+
+ setup_pageset(zone->pageset[cpu], zone_batchsize(zone));
+ }
+
+ return 0;
+bad:
+ for_each_zone(dzone) {
+ if (dzone == zone)
+ break;
+ kfree(dzone->pageset[cpu]);
+ dzone->pageset[cpu] = NULL;
+ }
+ return -ENOMEM;
+}
+
+static inline void free_zone_pagesets(int cpu)
+{
+#ifdef CONFIG_NUMA
+ struct zone *zone;
+
+ for_each_zone(zone) {
+ struct per_cpu_pageset *pset = zone_pcp(zone, cpu);
+
+ zone_pcp(zone, cpu) = NULL;
+ kfree(pset);
+ }
+#endif
+}
+
+static int __devinit pageset_cpuup_callback(struct notifier_block *nfb,
+ unsigned long action,
+ void *hcpu)
+{
+ int cpu = (long)hcpu;
+ int ret = NOTIFY_OK;
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ if (process_zones(cpu))
+ ret = NOTIFY_BAD;
+ break;
+#ifdef CONFIG_HOTPLUG_CPU
+ case CPU_DEAD:
+ free_zone_pagesets(cpu);
+ break;
+#endif
+ default:
+ break;
+ }
+ return ret;
+}
+
+static struct notifier_block pageset_notifier =
+ { &pageset_cpuup_callback, NULL, 0 };
+
+void __init setup_per_cpu_pageset()
+{
+ int err;
+
+ /* Initialize per_cpu_pageset for cpu 0.
+ * A cpuup callback will do this for every cpu
+ * as it comes online
+ */
+ err = process_zones(smp_processor_id());
+ BUG_ON(err);
+ register_cpu_notifier(&pageset_notifier);
+}
+
+#endif
+