The patch titled do_wait() wakeup optimization: change __wake_up_parent() to use filtered wakeup has been added to the -mm tree. Its filename is do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: do_wait() wakeup optimization: change __wake_up_parent() to use filtered wakeup From: Oleg Nesterov <oleg@xxxxxxxxxx> 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@xxxxxxxxxx> Acked-by: Roland McGrath <roland@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Ratan Nalumasu <rnalumasu@xxxxxxxxx> Cc: Vitaly Mayatskikh <vmayatsk@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/exit.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff -puN kernel/exit.c~do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup kernel/exit.c --- a/kernel/exit.c~do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup +++ a/kernel/exit.c @@ -1093,6 +1093,7 @@ struct wait_opts { int __user *wo_stat; struct rusage __user *wo_rusage; + wait_queue_t child_wait; int notask_error; }; @@ -1566,20 +1567,35 @@ static int ptrace_do_wait(struct wait_op return 0; } +static int child_wait_callback(wait_queue_t *wait, unsigned mode, + int sync, void *key) +{ + struct wait_opts *wo = container_of(wait, struct wait_opts, + child_wait); + struct task_struct *p = key; + + if (!eligible_child(wo, p)) + return 0; + + return default_wake_function(wait, mode, sync, key); +} + void __wake_up_parent(struct task_struct *p, struct task_struct *parent) { - wake_up_interruptible_sync(&parent->signal->wait_chldexit); + __wake_up_sync_key(&parent->signal->wait_chldexit, + TASK_INTERRUPTIBLE, 1, p); } static long do_wait(struct wait_opts *wo) { - DECLARE_WAITQUEUE(wait, current); struct task_struct *tsk; int retval; trace_sched_process_wait(wo->wo_pid); - add_wait_queue(¤t->signal->wait_chldexit,&wait); + init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); + wo->child_wait.private = current; + add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); repeat: /* * If there is nothing that can match our critiera just get out. @@ -1620,7 +1636,8 @@ notask: } end: __set_current_state(TASK_RUNNING); - remove_wait_queue(¤t->signal->wait_chldexit,&wait); + remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); + if (wo->wo_info) { struct siginfo __user *infop = wo->wo_info; _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are linux-next.patch cred_guard_mutex-do-not-return-eintr-to-user-space.patch rework-fix-is_single_threaded.patch getrusage-fill-ru_maxrss-value.patch getrusage-fill-ru_maxrss-value-update.patch ptrace-__ptrace_detach-do-__wake_up_parent-if-we-reap-the-tracee.patch do_wait-wakeup-optimization-shift-security_task_wait-from-eligible_child-to-wait_consider_task.patch do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup.patch do_wait-wakeup-optimization-child_wait_callback-check-__wnothread-case.patch signals-tracehook_notify_jctl-change.patch utrace-core.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html