From 128fb95650b3273a8dc9ba5514b6fe7db8ea30bf Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 6 Dec 2006 20:36:50 -0800 Subject: [PATCH] [PATCH] taskstats_exit_alloc: optimize/simplify If there are no listeners, every task does unneeded kmem_cache alloc/free on exit. We don't need listeners->sem for 'if (!list_empty())' check. Yes, we may have a false positive, but this doesn't differ from the case when the listener is unregistered after we drop the semaphore. So we don't need to do allocation beforehand. Signed-off-by: Oleg Nesterov Cc: Balbir Singh Acked-by: Shailabh Nagar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/taskstats.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/kernel/taskstats.c b/kernel/taskstats.c index f5f92014ae..d9d7c35762 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -416,7 +416,6 @@ err: void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu) { struct listener_list *listeners; - struct taskstats *tmp; /* * This is the cpu on which the task is exiting currently and will * be the one for which the exit event is sent, even if the cpu @@ -424,19 +423,11 @@ void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu) */ *mycpu = raw_smp_processor_id(); - *ptidstats = NULL; - tmp = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL); - if (!tmp) - return; - listeners = &per_cpu(listener_array, *mycpu); - down_read(&listeners->sem); - if (!list_empty(&listeners->list)) { - *ptidstats = tmp; - tmp = NULL; - } - up_read(&listeners->sem); - kfree(tmp); + + *ptidstats = NULL; + if (!list_empty(&listeners->list)) + *ptidstats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL); } /* Send pid data out on exit */ -- 2.39.5