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-rw-r--r--include/linux/percpu_counter.h11
-rw-r--r--lib/percpu_counter.c27
2 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index c88d67b..8a7d510 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -40,6 +40,7 @@ void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
s64 __percpu_counter_sum(struct percpu_counter *fbc);
+int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs);
static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
@@ -98,6 +99,16 @@ static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
fbc->count = amount;
}
+static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
+{
+ if (fbc->count > rhs)
+ return 1;
+ else if (fbc->count < rhs)
+ return -1;
+ else
+ return 0;
+}
+
static inline void
percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index aeaa6d7..ec9048e 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -137,6 +137,33 @@ static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
return NOTIFY_OK;
}
+/*
+ * Compare counter against given value.
+ * Return 1 if greater, 0 if equal and -1 if less
+ */
+int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
+{
+ s64 count;
+
+ count = percpu_counter_read(fbc);
+ /* Check to see if rough count will be sufficient for comparison */
+ if (abs(count - rhs) > (percpu_counter_batch*num_online_cpus())) {
+ if (count > rhs)
+ return 1;
+ else
+ return -1;
+ }
+ /* Need to use precise count */
+ count = percpu_counter_sum(fbc);
+ if (count > rhs)
+ return 1;
+ else if (count < rhs)
+ return -1;
+ else
+ return 0;
+}
+EXPORT_SYMBOL(percpu_counter_compare);
+
static int __init percpu_counter_startup(void)
{
compute_batch_value();
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