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From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
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Subject: Re: [PATCH v7 1/4] qrwlock: A queue read/write lock implementation
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Date: Wed, 18 Dec 2013 12:16:11 -0800
In-Reply-To: <20131218194615.GG16438@laptop.programming.kicks-ass.net> (Peter
	Zijlstra's message of "Wed, 18 Dec 2013 20:46:15 +0100")
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Peter Zijlstra <peterz@infradead.org> writes:

> On Wed, Dec 18, 2013 at 11:38:29AM -0800, Andi Kleen wrote:
>> (maybe it would be time to get rid of the patchable LOCK though?)
>
> With the argument that Intel simply doesn't ship UP chips anymore, with
> the exception of quark which should probably run custom UP kernels due
> to size constraints anyway?

That, and:

- Anything with a single core only has very fast LOCK
- LOCK generally became much faster everywhere.
- The original reason was for single cpu VM guests, but even those
should increasingly have at least two VCPUs.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only