Date: Thu, 21 Feb 2008 11:48:51 -0500 (EST)
From: Steven Rostedt <rostedt@goodmis.org>
To: Gregory Haskins <ghaskins@novell.com>
cc: mingo@elte.hu, a.p.zijlstra@chello.nl, tglx@linutronix.de,
       linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
       bill.huey@gmail.com, kevin@hilman.org, cminyard@mvista.com,
       dsingleton@mvista.com, dwalker@mvista.com, npiggin@suse.de,
       dsaxena@plexity.net, ak@suse.de, gregkh@suse.de, sdietrich@novell.com,
       pmorreale@novell.com, mkohari@novell.com
Subject: Re: [PATCH [RT] 10/14] adjust pi_lock usage in wakeup
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References: <20080221152504.4804.8724.stgit@novell1.haskins.net>
 <20080221152717.4804.56212.stgit@novell1.haskins.net>
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On Thu, 21 Feb 2008, Gregory Haskins wrote:

> From: Peter W.Morreale <pmorreale@novell.com>
>
> In wakeup_next_waiter(), we take the pi_lock, and then find out whether
> we have another waiter to add to the pending owner.  We can reduce
> contention on the pi_lock for the pending owner if we first obtain the
> pointer to the next waiter outside of the pi_lock.
>
> This patch adds a measureable increase in throughput.

I see how this may decrease contention (slightly less time in holding the
pi_lock). But, please, when stating something like: "adds a measurable
increase in throughput", show the benchmark numbers.

-- Steve

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