Re: [git pull] scheduler fixes

!MAILaRCHIVE_VOTE_RePLACE
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To: Matthew Wilcox <matthew@...>
Cc: Sven Wegener <sven.wegener@...>, Linus Torvalds <torvalds@...>, Zhang, Yanmin <yanmin_zhang@...>, Andi Kleen <andi@...>, LKML <linux-kernel@...>, Alexander Viro <viro@...>, Andrew Morton <akpm@...>, Thomas Gleixner <tglx@...>, H. Peter Anvin <hpa@...>
Date: Sunday, May 11, 2008 - 9:01 am

* Matthew Wilcox <matthew@wil.cx> wrote:


this needs to check for ret != 0 as well, otherwise we can be woken but 
a timeout can also trigger => we lose a wakeup. I.e. like the patch 
below. Hm?

	Ingo

----------------------------->
Subject: semaphore: fix #3
From: Ingo Molnar <mingo@elte.hu>
Date: Sun May 11 09:51:07 CEST 2008

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/semaphore.c |   24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

Index: linux/kernel/semaphore.c
===================================================================
--- linux.orig/kernel/semaphore.c
+++ linux/kernel/semaphore.c
@@ -194,6 +194,13 @@ struct semaphore_waiter {
 	struct task_struct *task;
 };
 
+static noinline void __sched __up(struct semaphore *sem)
+{
+	struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list,
+						struct semaphore_waiter, list);
+	wake_up_process(waiter->task);
+}
+
 /*
  * Because this function is inlined, the 'state' parameter will be
  * constant, and thus optimised away by the compiler.  Likewise the
@@ -231,6 +238,10 @@ static inline int __sched __down_common(
 	}
 
 	list_del(&waiter.list);
+	if (unlikely(!list_empty(&sem->wait_list)) &&
+					((sem->count > 1) || ret))
+		__up(sem);
+
 	return ret;
 }
 
@@ -254,9 +265,10 @@ static noinline int __sched __down_timeo
 	return __down_common(sem, TASK_UNINTERRUPTIBLE, jiffies);
 }
 
-static noinline void __sched __up(struct semaphore *sem)
-{
-	struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list,
-						struct semaphore_waiter, list);
-	wake_up_process(waiter->task);
-}
+
+	/*
+	 * Rotate sleepers - to make sure all of them get woken in case
+	 * of parallel up()s:
+	 */
+	list_move_tail(&waiter->list, &sem->wait_list);
+
--
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Messages in current thread:
AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Tue May 6, 1:48 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Tue May 6, 7:44 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Tue May 6, 10:11 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Tue May 6, 11:41 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andi Kleen, (Wed May 7, 7:00 am)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Wed May 7, 9:59 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 7:46 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andi Kleen, (Wed May 7, 8:21 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 10:36 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 12:20 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 12:35 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:05 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:24 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:36 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:55 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 1:59 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 2:17 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:49 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:19 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 10:44 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 2:43 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 3:14 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 3:39 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 4:44 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 5:21 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 5:30 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 5:29 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Thu May 8, 2:48 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:29 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 12:08 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Thu May 8, 12:17 am)
[git pull] scheduler fixes, Ingo Molnar, (Thu May 8, 11:10 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 7:03 am)
Re: [git pull] scheduler fixes, Sven Wegener, (Sun May 11, 10:10 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 9:01 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 9:06 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 9:45 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 7:48 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 8:50 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 8:52 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 9:02 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 9:54 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:22 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 10:32 am)
Re: [git pull] scheduler fixes, Linus Torvalds, (Sun May 11, 12:47 pm)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:46 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 9:26 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 10:00 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:18 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 10:42 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:48 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 11:19 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 11:29 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 10:11 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Tue May 13, 10:21 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 10:42 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Tue May 13, 11:28 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 1:13 pm)
Re: [git pull] scheduler fixes, Linus Torvalds, (Tue May 13, 1:22 pm)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 5:05 pm)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 7:14 am)
Re: [git pull] scheduler fixes, Adrian Bunk, (Thu May 8, 11:33 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Thu May 8, 11:41 am)
Re: [git pull] scheduler fixes, Adrian Bunk, (Thu May 8, 3:42 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:14 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andi Kleen, (Wed May 7, 10:57 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Wed May 7, 11:31 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 12:22 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Wed May 7, 10:35 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:00 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:02 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:26 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:28 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 3:05 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Tue May 6, 11:59 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 12:46 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 8:09 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 12:23 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 11:24 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:34 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 12:37 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Thu May 8, 10:58 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Tue May 6, 1:21 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 12:38 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 12:55 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:08 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:22 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:31 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:49 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 2:02 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:17 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 2:27 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:43 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 3:01 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 3:24 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 3:44 pm)
Oi. NFS people. Read this., Matthew Wilcox, (Wed May 7, 4:00 pm)
Re: Oi. NFS people. Read this., Trond Myklebust, (Wed May 7, 6:10 pm)
Re: Oi. NFS people. Read this., J. Bruce Fields, (Thu May 8, 9:43 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 3:09 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:47 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:25 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Wed May 7, 1:16 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:27 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 1:45 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Tue May 6, 1:39 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 2:49 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 1:31 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Tue May 6, 1:49 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Tue May 6, 2:07 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Sun May 11, 7:11 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 12:36 pm)
Re: AIM7 40% regression with 2.6.26-rc1, J. Bruce Fields, (Tue May 6, 12:44 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 12:42 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 4:28 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Tue May 6, 12:39 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 12:51 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 1:42 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Tue May 6, 12:45 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 7:18 am)