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Subject: Re: [PATCH 0/5] ipc/sem.c: multiple fixes
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@google.com>,
        Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <efault@gmx.de>
Date: Mon, 17 Oct 2011 14:43:48 +0200
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On Sat, 2011-10-15 at 15:21 +0200, Manfred Spraul wrote:
> Hi all,
> 
> The wakeup scheme used by semtimedop() does not work as intended on -rt.
> 
> The following series:
> - fixes one bug that I noticed while thinking about a -rt compatible
>   implementation
> - prevents the code from returning to user space due to spurious wakeups.
>   (noticed by Peter Zijlstra)
> - moves private structures from include/linux/sem.h to ipc/sem.c
> - saves some memory if sysvipc is disabled.
> - reworks the wakeup scheme and adds a 2nd wakeup scheme that is based
>   on a completion. For CONFIG_PREEMPT_RT_BASE, this scheme is used.
> 
> What do you think?
> The rework of the wakeup should also help to convert the code to
> using the wake_up_list framework.
> 
> Andrew: Could you replace the patches in -mm with this series?
> I would prefer to keep the current scheme as the default, it's
> ~5% faster (6.5 usec vs. 6.8 usec per wakeup).
> 
> The patches pass checkpatch.pl and I didn't observe any problems
> with my test apps.

For patches 1-4:

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

I still need to kick my brain in gear and parse patch 5.