ia64/linux-2.6.18-xen.hg

view lib/percpu_counter.c @ 782:9ab1c319531f

merge with linux-2.6.18-xen.hg
author Isaku Yamahata <yamahata@valinux.co.jp>
date Wed Jan 28 13:07:23 2009 +0900 (2009-01-28)
parents 831230e53067
children
line source
1 /*
2 * Fast batching percpu counters.
3 */
5 #include <linux/percpu_counter.h>
6 #include <linux/module.h>
8 void percpu_counter_mod(struct percpu_counter *fbc, s32 amount)
9 {
10 long count;
11 s32 *pcount;
12 int cpu = get_cpu();
14 pcount = per_cpu_ptr(fbc->counters, cpu);
15 count = *pcount + amount;
16 if (count >= FBC_BATCH || count <= -FBC_BATCH) {
17 spin_lock(&fbc->lock);
18 fbc->count += count;
19 *pcount = 0;
20 spin_unlock(&fbc->lock);
21 } else {
22 *pcount = count;
23 }
24 put_cpu();
25 }
26 EXPORT_SYMBOL(percpu_counter_mod);
28 /*
29 * Add up all the per-cpu counts, return the result. This is a more accurate
30 * but much slower version of percpu_counter_read_positive()
31 */
32 s64 percpu_counter_sum(struct percpu_counter *fbc)
33 {
34 s64 ret;
35 int cpu;
37 spin_lock(&fbc->lock);
38 ret = fbc->count;
39 for_each_possible_cpu(cpu) {
40 s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
41 ret += *pcount;
42 }
43 spin_unlock(&fbc->lock);
44 return ret < 0 ? 0 : ret;
45 }
46 EXPORT_SYMBOL(percpu_counter_sum);