linux-kernel - Re: [PATCH v7 1/4] spinlock: A new lockref structure for lockless update of refcount

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Date:	Fri, 30 Aug 2013 12:12:27 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	sedat.dilek@...il.com
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Waiman Long <waiman.long@...com>,
	Ingo Molnar <mingo@...nel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Jeff Layton <jlayton@...hat.com>,
	Miklos Szeredi <mszeredi@...e.cz>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	"Chandramouleeswaran, Aswin" <aswin@...com>,
	"Norton, Scott J" <scott.norton@...com>
Subject: Re: [PATCH v7 1/4] spinlock: A new lockref structure for lockless
 update of refcount

On Fri, 30 Aug 2013 17:38:47 +0200
Sedat Dilek <sedat.dilek@...il.com> wrote:


> A Samsung series-5 ultrabook.
> 
> $ grep "model name" /proc/cpuinfo | uniq
> model name      : Intel(R) Core(TM) i5-2467M CPU @ 1.60GHz

I believe the number of CPUs is more important. But as this is an
ultrabook, I doubt that is very high.

Now I know this isn't going to be popular, but I'll suggest it anyway.
What about only implementing the lockref locking when CPUs are greater
than 7, 7 or less will still use the normal optimized spinlocks.

-- Steve
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