#ifdef CONFIG_SMP
+static 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;
+}
+
static int calculate_threshold(struct zone *zone)
{
int threshold;
}
}
+void reduce_pgdat_percpu_threshold(pg_data_t *pgdat)
+{
+ struct zone *zone;
+ int cpu;
+ int threshold;
+ int i;
+
+ get_online_cpus();
+ for (i = 0; i < pgdat->nr_zones; i++) {
+ zone = &pgdat->node_zones[i];
+ if (!zone->percpu_drift_mark)
+ continue;
+
+ threshold = calculate_pressure_threshold(zone);
+ for_each_online_cpu(cpu)
+ per_cpu_ptr(zone->pageset, cpu)->stat_threshold
+ = threshold;
+ }
+ put_online_cpus();
+}
+
+void restore_pgdat_percpu_threshold(pg_data_t *pgdat)
+{
+ struct zone *zone;
+ int cpu;
+ int threshold;
+ int i;
+
+ get_online_cpus();
+ for (i = 0; i < pgdat->nr_zones; i++) {
+ zone = &pgdat->node_zones[i];
+ if (!zone->percpu_drift_mark)
+ continue;
+
+ threshold = calculate_threshold(zone);
+ for_each_online_cpu(cpu)
+ per_cpu_ptr(zone->pageset, cpu)->stat_threshold
+ = threshold;
+ }
+ put_online_cpus();
+}
+
/*
* For use when we know that interrupts are disabled.
*/
"\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),