This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / lib / percpu_counter.c

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
new file mode 100644 (file)
index 0000000..8504490
--- /dev/null
+++ b/lib/percpu_counter.c
@@ -0,0 +1,46 @@
+/*
+ * Fast batching percpu counters.
+ */
+
+#include <linux/percpu_counter.h>
+#include <linux/module.h>
+
+void percpu_counter_mod(struct percpu_counter *fbc, s32 amount)
+{
+       long count;
+       s32 *pcount;
+       int cpu = get_cpu();
+
+       pcount = per_cpu_ptr(fbc->counters, cpu);
+       count = *pcount + amount;
+       if (count >= FBC_BATCH || count <= -FBC_BATCH) {
+               spin_lock(&fbc->lock);
+               fbc->count += count;
+               *pcount = 0;
+               spin_unlock(&fbc->lock);
+       } else {
+               *pcount = count;
+       }
+       put_cpu();
+}
+EXPORT_SYMBOL(percpu_counter_mod);
+
+/*
+ * Add up all the per-cpu counts, return the result.  This is a more accurate
+ * but much slower version of percpu_counter_read_positive()
+ */
+s64 percpu_counter_sum(struct percpu_counter *fbc)
+{
+       s64 ret;
+       int cpu;
+
+       spin_lock(&fbc->lock);
+       ret = fbc->count;
+       for_each_possible_cpu(cpu) {
+               s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
+               ret += *pcount;
+       }
+       spin_unlock(&fbc->lock);
+       return ret < 0 ? 0 : ret;
+}
+EXPORT_SYMBOL(percpu_counter_sum);