lib: percpu_counter variable batch

Because the current batch setup has an quadric error bound on the counter, allow for an alternative setup. Signed-off-by: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ashr · Oct 17, 2007 · 252e0ba · 252e0ba
1 parent 3cb4f9f
commit 252e0ba
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Showing 2 changed files with 12 additions and 4 deletions.
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
@@ -32,9 +32,14 @@ struct percpu_counter {
 
 void percpu_counter_init(struct percpu_counter *fbc, s64 amount);
 void percpu_counter_destroy(struct percpu_counter *fbc);
-void percpu_counter_add(struct percpu_counter *fbc, s32 amount);
+void __percpu_counter_add(struct percpu_counter *fbc, s32 amount, s32 batch);
 s64 percpu_counter_sum(struct percpu_counter *fbc);
 
+static inline void percpu_counter_add(struct percpu_counter *fbc, s32 amount)
+{
+	__percpu_counter_add(fbc, amount, FBC_BATCH);
+}
+
 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
 {
 	return fbc->count;
@@ -70,6 +75,9 @@ static inline void percpu_counter_destroy(struct percpu_counter *fbc)
 {
 }
 
+#define __percpu_counter_add(fbc, amount, batch) \
+	percpu_counter_add(fbc, amount)
+
 static inline void
 percpu_counter_add(struct percpu_counter *fbc, s32 amount)
 {

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
@@ -14,15 +14,15 @@ static LIST_HEAD(percpu_counters);
 static DEFINE_MUTEX(percpu_counters_lock);
 #endif
 
-void percpu_counter_add(struct percpu_counter *fbc, s32 amount)
+void __percpu_counter_add(struct percpu_counter *fbc, s32 amount, s32 batch)
 {
 	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) {
+	if (count >= batch || count <= -batch) {
 		spin_lock(&fbc->lock);
 		fbc->count += count;
 		*pcount = 0;
@@ -32,7 +32,7 @@ void percpu_counter_add(struct percpu_counter *fbc, s32 amount)
 	}
 	put_cpu();
 }
-EXPORT_SYMBOL(percpu_counter_add);
+EXPORT_SYMBOL(__percpu_counter_add);
 
 /*
  * Add up all the per-cpu counts, return the result.  This is a more accurate