From c67ad917cbf21b2862e2cf8e8b28339872ef7927 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sun, 15 Jul 2007 23:39:51 -0700 Subject: percpu_counters(): use cpu notifiers per-cpu counters presently must iterate over all possible CPUs in the exhaustive percpu_counter_sum(). But it can be much better to only iterate over the presently-online CPUs. To do this, we must arrange for an offlined CPU's count to be spilled into the counter's central count. We can do this for all percpu_counters in the machine by linking them into a single global list and walking that list at CPU_DEAD time. (I hope. Might have race windows in which the percpu_counter_sum() count is inaccurate?) Cc: Gautham R Shenoy Cc: Oleg Nesterov Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/percpu_counter.h | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) (limited to 'include') diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index f5aa593ccf32..3d9f70972cdf 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -8,6 +8,7 @@ #include #include +#include #include #include #include @@ -17,6 +18,9 @@ struct percpu_counter { spinlock_t lock; s64 count; +#ifdef CONFIG_HOTPLUG_CPU + struct list_head list; /* All percpu_counters are on a list */ +#endif s32 *counters; }; @@ -26,18 +30,8 @@ struct percpu_counter { #define FBC_BATCH (NR_CPUS*4) #endif -static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount) -{ - spin_lock_init(&fbc->lock); - fbc->count = amount; - fbc->counters = alloc_percpu(s32); -} - -static inline void percpu_counter_destroy(struct percpu_counter *fbc) -{ - free_percpu(fbc->counters); -} - +void percpu_counter_init(struct percpu_counter *fbc, s64 amount); +void percpu_counter_destroy(struct percpu_counter *fbc); void percpu_counter_mod(struct percpu_counter *fbc, s32 amount); s64 percpu_counter_sum(struct percpu_counter *fbc); -- cgit v1.2.3-59-g8ed1b