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

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Message-ID: <20130830171707.GV31370@twins.programming.kicks-ass.net>
Date:	Fri, 30 Aug 2013 19:17:07 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Waiman Long <Waiman.Long@...com>,
	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>,
	Steven Rostedt <rostedt@...dmis.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 Thu, Aug 29, 2013 at 09:43:07AM -0700, Linus Torvalds wrote:

> We'll see. The real problem is that I'm not sure if I can even see the
> scalability issue on any machine I actually personally want to use
> (read: silent). On my current  system I can only get up to 15%
> _raw_spin_lock by just stat'ing the same file over and over and over
> again from lots of threads.

Yeah, silent basically limits you to i7 single socket systems and sadly
Intel doesn't seem to want to make those with more than 4 cores on :/

I've got a i7-K part (SNB iirc) with a _huge_ scythe cooler and a high
efficiency fanless PSU for a system that's near noiseless -- as in my
Thinkpad actually makes more noise.
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