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author | Andrew Morton <akpm@linux-foundation.org> | 2007-07-15 23:39:51 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-16 09:05:41 -0700 |
commit | c67ad917cbf21b2862e2cf8e8b28339872ef7927 (patch) | |
tree | 362d8cf8668998b8cd5deb611693f584b8df5ee5 /include | |
parent | 85420ccad1610f123365eec89848ef25641bc6b7 (diff) | |
download | linux-c67ad917cbf21b2862e2cf8e8b28339872ef7927.tar.gz linux-c67ad917cbf21b2862e2cf8e8b28339872ef7927.tar.bz2 linux-c67ad917cbf21b2862e2cf8e8b28339872ef7927.zip |
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 <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/percpu_counter.h | 18 |
1 files changed, 6 insertions, 12 deletions
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 <linux/spinlock.h> #include <linux/smp.h> +#include <linux/list.h> #include <linux/threads.h> #include <linux/percpu.h> #include <linux/types.h> @@ -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); |