diff options
| -rw-r--r-- | include/linux/percpu_counter.h | 4 | ||||
| -rw-r--r-- | lib/percpu_counter.c | 19 |
2 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index 0a4f54dd4737..01861eebed79 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -44,6 +44,7 @@ void percpu_counter_add_batch(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, s32 batch); +void percpu_counter_sync(struct percpu_counter *fbc); static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs) { @@ -172,6 +173,9 @@ static inline bool percpu_counter_initialized(struct percpu_counter *fbc) return true; } +static inline void percpu_counter_sync(struct percpu_counter *fbc) +{ +} #endif /* CONFIG_SMP */ static inline void percpu_counter_inc(struct percpu_counter *fbc) diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c index a66595ba5543..a2345de90e93 100644 --- a/lib/percpu_counter.c +++ b/lib/percpu_counter.c @@ -99,6 +99,25 @@ void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch) EXPORT_SYMBOL(percpu_counter_add_batch); /* + * For percpu_counter with a big batch, the devication of its count could + * be big, and there is requirement to reduce the deviation, like when the + * counter's batch could be runtime decreased to get a better accuracy, + * which can be achieved by running this sync function on each CPU. + */ +void percpu_counter_sync(struct percpu_counter *fbc) +{ + unsigned long flags; + s64 count; + + raw_spin_lock_irqsave(&fbc->lock, flags); + count = __this_cpu_read(*fbc->counters); + fbc->count += count; + __this_cpu_sub(*fbc->counters, count); + raw_spin_unlock_irqrestore(&fbc->lock, flags); +} +EXPORT_SYMBOL(percpu_counter_sync); + +/* * Add up all the per-cpu counts, return the result. This is a more accurate * but much slower version of percpu_counter_read_positive() */ |