delayed wakeup list [LWN.net]

From:		Peter Zijlstra <a.p.zijlstra@chello.nl>
To:		Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>
Subject:		[RFC][PATCH 0/3] delayed wakeup list
Date:		Wed, 14 Sep 2011 15:30:34 +0200
Message-ID:		<20110914133034.687048806@chello.nl>
Cc:		linux-kernel@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>, Darren Hart <dvhart@linux.intel.com>, Manfred Spraul <manfred@colorfullife.com>, David Miller <davem@davemloft.net>, Eric Dumazet <eric.dumazet@gmail.com>, Mike Galbraith <efault@gmx.de>, Peter Zijlstra <a.p.zijlstra@chello.nl>
Archive-link:		Article, Thread

This patch-set provides the infrastructure to delay/batch task wakeups.

This is useful for locking primitives that can effect multiple wakeups
per operation and want to avoid lock internal lock contention by
delaying the wakeups until we've released the lock internal locks.

Patch 2 converts futexes
Patch 3 converts sysv sems, and is broken

[ I've been staring at patch 3 way too long, so I thought I'd post it just
  to get a few more eyes on it.. ]

Alternatively it can be used to avoid issuing multiple wakeups, and
thus save a few cycles, in packet processing. Queue all target tasks
and wakeup once you've processed all packets. That way you avoid
waking the target task multiple times if there were multiple packets
for the same task.

No actual such usage yet, but ISTR talking to some net folks a long while back
about this, is there still interest, Dave, Eric?

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