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Subject[PATCH 04/10] lib: percpu_counter_mod64
Add percpu_counter_mod64() to allow large modifications.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/percpu_counter.h | 9 +++++++++
lib/percpu_counter.c | 28 ++++++++++++++++++++++++++++
2 files changed, 37 insertions(+)
Index: linux-2.6/include/linux/percpu_counter.h
===================================================================
--- linux-2.6.orig/include/linux/percpu_counter.h 2007-04-12 13:54:55.000000000 +0200
+++ linux-2.6/include/linux/percpu_counter.h 2007-04-12 14:00:21.000000000 +0200
@@ -36,6 +36,7 @@ static inline void percpu_counter_destro
}

void percpu_counter_mod(struct percpu_counter *fbc, s32 amount);
+void percpu_counter_mod64(struct percpu_counter *fbc, s64 amount);
s64 percpu_counter_sum(struct percpu_counter *fbc);

static inline s64 percpu_counter_read(struct percpu_counter *fbc)
@@ -81,6 +82,14 @@ percpu_counter_mod(struct percpu_counter
preempt_enable();
}

+static inline void
+percpu_counter_mod64(struct percpu_counter *fbc, s64 amount)
+{
+ preempt_disable();
+ fbc->count += amount;
+ preempt_enable();
+}
+
static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
return fbc->count;
Index: linux-2.6/lib/percpu_counter.c
===================================================================
--- linux-2.6.orig/lib/percpu_counter.c 2006-07-31 13:07:38.000000000 +0200
+++ linux-2.6/lib/percpu_counter.c 2007-04-12 14:17:12.000000000 +0200
@@ -25,6 +25,34 @@ void percpu_counter_mod(struct percpu_co
}
EXPORT_SYMBOL(percpu_counter_mod);

+void percpu_counter_mod64(struct percpu_counter *fbc, s64 amount)
+{
+ long count;
+ s32 *pcount;
+ int cpu;
+
+ if (amount >= FBC_BATCH || amount <= -FBC_BATCH) {
+ spin_lock(&fbc->lock);
+ fbc->count += amount;
+ spin_unlock(&fbc->lock);
+ return;
+ }
+
+ 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_mod64);
+
/*
* Add up all the per-cpu counts, return the result. This is a more accurate
* but much slower version of percpu_counter_read_positive()
--

-
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