[PATCH] Add prefetching to get_page_state()

Fetch the next cacheline as we're counting up the fields in this one.

mm/page_alloc.c

@@ -715,16 +715,21 @@ EXPORT_PER_CPU_SYMBOL(page_states);
 
 void __get_page_state(struct page_state *ret, int nr)
 {
-	int cpu;
+	int cpu = 0;
 
 	memset(ret, 0, sizeof(*ret));
-	for (cpu = 0; cpu < NR_CPUS; cpu++) {
+	while (cpu < NR_CPUS) {
 		unsigned long *in, *out, off;
 
-		if (!cpu_online(cpu))
+		if (!cpu_online(cpu)) {
+			cpu++;
 			continue;
+		}
 
 		in = (unsigned long *)&per_cpu(page_states, cpu);
+		cpu++;
+		if (cpu < NR_CPUS && cpu_online(cpu))
+			prefetch(&per_cpu(page_states, cpu));
 		out = (unsigned long *)ret;
 		for (off = 0; off < nr; off++)
 			*out++ += *in++;