[PATCH] taskstats_tgid_alloc: optimization

Every subthread (except first) does unneeded kmem_cache_alloc/kmem_cache_free.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/taskstats_kern.h b/include/linux/taskstats_kern.h
index a437ca0d226b..664224008fb2 100644
--- a/include/linux/taskstats_kern.h
+++ b/include/linux/taskstats_kern.h
@@ -32,6 +32,9 @@ static inline void taskstats_tgid_alloc(struct signal_struct *sig)
         struct taskstats *stats;
         unsigned long flags;
 
+        if (sig->stats != NULL)
+                return;
+
         stats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
         if (!stats)
                 return;