linux-kernel - Re: [PATCH RFC 0/7] x86: convert ticketlocks to C and remove duplicate code

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Message-ID: <4E28B749.10304@goop.org>
Date:	Thu, 21 Jul 2011 16:33:29 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Nick Piggin <npiggin@...nel.dk>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: Re: [PATCH RFC 0/7] x86: convert ticketlocks to C and remove duplicate
 code

On 06/29/2011 01:44 PM, Andi Kleen wrote:
> Jeremy Fitzhardinge <jeremy@...p.org> writes:
>> I couldn't measure a consistent performance difference between the two
>> implemenations; there seemed to be +/- ~1% +/-, which is the level of
>> variation I see from simply recompiling the kernel with slightly
>> different code alignment.
> I ran your new locks in my lock tester and I have a similar experience.
> There's some variation, but it seems to be in the usual variance.
> In some cases the C locks were actually faster.

Yes, I observed cases where they were faster.  What is your lock
tester?  Does it test the lock code in isolation, or in situ?

Thanks,
    J
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