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Message-ID: <20110418134518.GD15951@redhat.com>
Date: Mon, 18 Apr 2011 15:45:18 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Tejun Heo <tj@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: "Nikita V. Youshchenko" <nyoushchenko@...sta.com>,
Matt Fleming <matt@...sole-pimps.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/7] signal: retarget_shared_pending: optimize
while_each_thread() loop
retarget_shared_pending() blindly does recalc_sigpending_and_wake() for
every sub-thread, this is suboptimal. We can check t->blocked and stop
looping once every bit in shared_pending has the new target.
Note: we do not take task_is_stopped_or_traced(t) into account, we are
not trying to speed up the signal delivery or to avoid the unnecessary
(but harmless) signal_wake_up(0) in this unlikely case.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
kernel/signal.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
--- sigprocmask/kernel/signal.c~3_optimize_retarget_loop 2011-04-17 21:08:05.000000000 +0200
+++ sigprocmask/kernel/signal.c 2011-04-17 21:28:21.000000000 +0200
@@ -2033,8 +2033,18 @@ static void retarget_shared_pending(stru
t = tsk;
while_each_thread(tsk, t) {
- if (!signal_pending(t) && !(t->flags & PF_EXITING))
- recalc_sigpending_and_wake(t);
+ if ((t->flags & PF_EXITING))
+ continue;
+ if (!has_pending_signals(&shared_pending, &t->blocked))
+ continue;
+
+ sigandsets(&shared_pending, &shared_pending, &t->blocked);
+
+ if (!signal_pending(t))
+ signal_wake_up(t, 0);
+
+ if (sigisemptyset(&shared_pending))
+ break;
}
}
--
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