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| author | Oleg Nesterov <oleg@redhat.com> | 2009-12-17 15:27:15 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-17 15:45:31 -0800 |
| commit | 9cd80bbb07fcd6d4d037fad4297496d3b132ac6b (patch) | |
| tree | 322216d34b6d5ba2366f53ba0d677950c4cde766 /kernel/fork.c | |
| parent | 0f67b0b0392ccca98459bf40b36c0037793b5f71 (diff) | |
| download | linux-9cd80bbb07fcd6d4d037fad4297496d3b132ac6b.tar.gz linux-9cd80bbb07fcd6d4d037fad4297496d3b132ac6b.tar.bz2 linux-9cd80bbb07fcd6d4d037fad4297496d3b132ac6b.zip | |
do_wait() optimization: do not place sub-threads on task_struct->children list
Thanks to Roland who pointed out de_thread() issues.
Currently we add sub-threads to ->real_parent->children list. This buys
nothing but slows down do_wait().
With this patch ->children contains only main threads (group leaders).
The only complication is that forget_original_parent() should iterate over
sub-threads by hand, and de_thread() needs another list_replace() when it
changes ->group_leader.
Henceforth do_wait_thread() can never see task_detached() && !EXIT_DEAD
tasks, we can remove this check (and we can unify do_wait_thread() and
ptrace_do_wait()).
This change can confuse the optimistic search in mm_update_next_owner(),
but this is fixable and minor.
Perhaps badness() and oom_kill_process() should be updated, but they
should be fixed in any case.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ratan Nalumasu <rnalumasu@gmail.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 202a0ba63d3c..5b2959b3ffc2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1291,7 +1291,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, } if (likely(p->pid)) { - list_add_tail(&p->sibling, &p->real_parent->children); tracehook_finish_clone(p, clone_flags, trace); if (thread_group_leader(p)) { @@ -1303,6 +1302,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, p->signal->tty = tty_kref_get(current->signal->tty); attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); attach_pid(p, PIDTYPE_SID, task_session(current)); + list_add_tail(&p->sibling, &p->real_parent->children); list_add_tail_rcu(&p->tasks, &init_task.tasks); __get_cpu_var(process_counts)++; } |