#ifdef CONFIG_SMP
-static int calculate_threshold(struct zone *zone)
+int calculate_pressure_threshold(struct zone *zone)
+{
+ int threshold;
+ int watermark_distance;
+
+ /*
+ * As vmstats are not up to date, there is drift between the estimated
+ * and real values. For high thresholds and a high number of CPUs, it
+ * is possible for the min watermark to be breached while the estimated
+ * value looks fine. The pressure threshold is a reduced value such
+ * that even the maximum amount of drift will not accidentally breach
+ * the min watermark
+ */
+ watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
+ threshold = max(1, (int)(watermark_distance / num_online_cpus()));
+
+ /*
+ * Maximum threshold is 125
+ */
+ threshold = min(125, threshold);
+
+ return threshold;
+}
+
+int calculate_normal_threshold(struct zone *zone)
{
int threshold;
int mem; /* memory in 128 MB units */
for_each_populated_zone(zone) {
unsigned long max_drift, tolerate_drift;
- threshold = calculate_threshold(zone);
+ threshold = calculate_normal_threshold(zone);
for_each_online_cpu(cpu)
per_cpu_ptr(zone->pageset, cpu)->stat_threshold
}
}
+void set_pgdat_percpu_threshold(pg_data_t *pgdat,
+ int (*calculate_pressure)(struct zone *))
+{
+ struct zone *zone;
+ int cpu;
+ int threshold;
+ int i;
+
+ for (i = 0; i < pgdat->nr_zones; i++) {
+ zone = &pgdat->node_zones[i];
+ if (!zone->percpu_drift_mark)
+ continue;
+
+ threshold = (*calculate_pressure)(zone);
+ for_each_possible_cpu(cpu)
+ per_cpu_ptr(zone->pageset, cpu)->stat_threshold
+ = threshold;
+ }
+}
+
/*
* For use when we know that interrupts are disabled.
*/
void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
int delta)
{
- struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset);
-
- s8 *p = pcp->vm_stat_diff + item;
+ struct per_cpu_pageset __percpu *pcp = zone->pageset;
+ s8 __percpu *p = pcp->vm_stat_diff + item;
long x;
+ long t;
+
+ x = delta + __this_cpu_read(*p);
- x = delta + *p;
+ t = __this_cpu_read(pcp->stat_threshold);
- if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) {
+ if (unlikely(x > t || x < -t)) {
zone_page_state_add(x, zone, item);
x = 0;
}
- *p = x;
+ __this_cpu_write(*p, x);
}
EXPORT_SYMBOL(__mod_zone_page_state);
-/*
- * For an unknown interrupt state
- */
-void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
- int delta)
-{
- unsigned long flags;
-
- local_irq_save(flags);
- __mod_zone_page_state(zone, item, delta);
- local_irq_restore(flags);
-}
-EXPORT_SYMBOL(mod_zone_page_state);
-
/*
* Optimized increment and decrement functions.
*
*/
void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
{
- struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset);
- s8 *p = pcp->vm_stat_diff + item;
+ struct per_cpu_pageset __percpu *pcp = zone->pageset;
+ s8 __percpu *p = pcp->vm_stat_diff + item;
+ s8 v, t;
- (*p)++;
+ v = __this_cpu_inc_return(*p);
+ t = __this_cpu_read(pcp->stat_threshold);
+ if (unlikely(v > t)) {
+ s8 overstep = t >> 1;
- if (unlikely(*p > pcp->stat_threshold)) {
- int overstep = pcp->stat_threshold / 2;
-
- zone_page_state_add(*p + overstep, zone, item);
- *p = -overstep;
+ zone_page_state_add(v + overstep, zone, item);
+ __this_cpu_write(*p, -overstep);
}
}
void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
{
- struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset);
- s8 *p = pcp->vm_stat_diff + item;
-
- (*p)--;
+ struct per_cpu_pageset __percpu *pcp = zone->pageset;
+ s8 __percpu *p = pcp->vm_stat_diff + item;
+ s8 v, t;
- if (unlikely(*p < - pcp->stat_threshold)) {
- int overstep = pcp->stat_threshold / 2;
+ v = __this_cpu_dec_return(*p);
+ t = __this_cpu_read(pcp->stat_threshold);
+ if (unlikely(v < - t)) {
+ s8 overstep = t >> 1;
- zone_page_state_add(*p - overstep, zone, item);
- *p = overstep;
+ zone_page_state_add(v - overstep, zone, item);
+ __this_cpu_write(*p, overstep);
}
}
}
EXPORT_SYMBOL(__dec_zone_page_state);
+#ifdef CONFIG_CMPXCHG_LOCAL
+/*
+ * If we have cmpxchg_local support then we do not need to incur the overhead
+ * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
+ *
+ * mod_state() modifies the zone counter state through atomic per cpu
+ * operations.
+ *
+ * Overstep mode specifies how overstep should handled:
+ * 0 No overstepping
+ * 1 Overstepping half of threshold
+ * -1 Overstepping minus half of threshold
+*/
+static inline void mod_state(struct zone *zone,
+ enum zone_stat_item item, int delta, int overstep_mode)
+{
+ struct per_cpu_pageset __percpu *pcp = zone->pageset;
+ s8 __percpu *p = pcp->vm_stat_diff + item;
+ long o, n, t, z;
+
+ do {
+ z = 0; /* overflow to zone counters */
+
+ /*
+ * The fetching of the stat_threshold is racy. We may apply
+ * a counter threshold to the wrong the cpu if we get
+ * rescheduled while executing here. However, the following
+ * will apply the threshold again and therefore bring the
+ * counter under the threshold.
+ */
+ t = this_cpu_read(pcp->stat_threshold);
+
+ o = this_cpu_read(*p);
+ n = delta + o;
+
+ if (n > t || n < -t) {
+ int os = overstep_mode * (t >> 1) ;
+
+ /* Overflow must be added to zone counters */
+ z = n + os;
+ n = -os;
+ }
+ } while (this_cpu_cmpxchg(*p, o, n) != o);
+
+ if (z)
+ zone_page_state_add(z, zone, item);
+}
+
+void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
+ int delta)
+{
+ mod_state(zone, item, delta, 0);
+}
+EXPORT_SYMBOL(mod_zone_page_state);
+
+void inc_zone_state(struct zone *zone, enum zone_stat_item item)
+{
+ mod_state(zone, item, 1, 1);
+}
+
+void inc_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+ mod_state(page_zone(page), item, 1, 1);
+}
+EXPORT_SYMBOL(inc_zone_page_state);
+
+void dec_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+ mod_state(page_zone(page), item, -1, -1);
+}
+EXPORT_SYMBOL(dec_zone_page_state);
+#else
+/*
+ * Use interrupt disable to serialize counter updates
+ */
+void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
+ int delta)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __mod_zone_page_state(zone, item, delta);
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(mod_zone_page_state);
+
void inc_zone_state(struct zone *zone, enum zone_stat_item item)
{
unsigned long flags;
local_irq_restore(flags);
}
EXPORT_SYMBOL(dec_zone_page_state);
+#endif
/*
* Update the zone counters for one cpu.
"numa_local",
"numa_other",
#endif
+ "nr_anon_transparent_hugepages",
"nr_dirty_threshold",
"nr_dirty_background_threshold",
"\n scanned %lu"
"\n spanned %lu"
"\n present %lu",
- zone_nr_free_pages(zone),
+ zone_page_state(zone, NR_FREE_PAGES),
min_wmark_pages(zone),
low_wmark_pages(zone),
high_wmark_pages(zone),
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
- cancel_rearming_delayed_work(&per_cpu(vmstat_work, cpu));
+ cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
per_cpu(vmstat_work, cpu).work.func = NULL;
break;
case CPU_DOWN_FAILED:
projects / mv-sheeva.git / blobdiff