From 3cbc564024d8f174202f023e8a2991782f6a9431 Mon Sep 17 00:00:00 2001 From: Ravikiran G Thirumalai Date: Fri, 23 Jun 2006 02:05:40 -0700 Subject: [PATCH] percpu_counters: create lib/percpu_counter.c - Move percpu_counter routines from mm/swap.c to lib/percpu_counter.c Signed-off-by: Ravikiran Thirumalai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/percpu_counter.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 lib/percpu_counter.c (limited to 'lib/percpu_counter.c') diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c new file mode 100644 index 00000000000..7a87003f8e8 --- /dev/null +++ b/lib/percpu_counter.c @@ -0,0 +1,46 @@ +/* + * Fast batching percpu counters. + */ + +#include +#include + +void percpu_counter_mod(struct percpu_counter *fbc, long amount) +{ + long count; + long *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() + */ +long percpu_counter_sum(struct percpu_counter *fbc) +{ + long ret; + int cpu; + + spin_lock(&fbc->lock); + ret = fbc->count; + for_each_possible_cpu(cpu) { + long *pcount = per_cpu_ptr(fbc->counters, cpu); + ret += *pcount; + } + spin_unlock(&fbc->lock); + return ret < 0 ? 0 : ret; +} +EXPORT_SYMBOL(percpu_counter_sum); -- cgit v1.2.3