do_wait() wakeup optimization: change __wake_up_parent() to use filtered wakeup
authorOleg Nesterov <oleg@redhat.com>
Wed, 23 Sep 2009 22:56:46 +0000 (15:56 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 24 Sep 2009 14:20:59 +0000 (07:20 -0700)
commit0b7570e77f7c3abd43107dabc47ea89daf9a1cba
tree8dd93b4a189b4e98384d4470a289ecfb7818cc26
parenta2322e1d272938d192d8c24cdacf57c0c7a2683f
do_wait() wakeup optimization: change __wake_up_parent() to use filtered wakeup

Ratan Nalumasu reported that in a process with many threads doing
unnecessary wakeups.  Every waiting thread in the process wakes up to loop
through the children and see that the only ones it cares about are still
not ready.

Now that we have struct wait_opts we can change do_wait/__wake_up_parent
to use filtered wakeups.

We can make child_wait_callback() more clever later, right now it only
checks eligible_child().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ratan Nalumasu <rnalumasu@gmail.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c
security/selinux/hooks.c