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Message-ID: <4577E095.1040904@yahoo.com.au>
Date: Thu, 07 Dec 2006 20:36:21 +1100
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Larry Finger <Larry.Finger@lwfinger.net>, Andrew Morton <akpm@osdl.org>,
       Benoit Boissinot <bboissin@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.19-rc5-mm1 progression
References: <456718F6.8040902@lwfinger.net>	 <40f323d00611240836q6bcf7374gd47c7a97d1d4f8e3@mail.gmail.com>	 <20061125112437.3d46eff4.akpm@osdl.org>  <4574E86B.10403@lwfinger.net> <1165407170.12561.12.camel@twins>
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Peter Zijlstra wrote:
> On Mon, 2006-12-04 at 21:32 -0600, Larry Finger wrote:

>>There are at least two patches in 2.6.19-rc5-mm2 that make my system much more responsive for 
>>interactive jobs. The one that has the majority of the effect is:
>>
>>radix-tree-rcu-lockless-readside.patch
>>
>>I have not been able to isolate the second patch, which has the lesser effect. All I can say is that 
>>it occurred before the above patch in patches/series. This patch was tested against 2.6.19 and fixed 
>>most of the problem on that version.
> 
> 
> Curious...
> 
> This patch introduces the direct pointer optimisation for single element
> radix trees and makes the radix tree safe to read in a lock-less manner
> which is not used -yet-. The only difference that that should have is
> that the elements are freed using rcu callback instead of directly.
> 
> /me puzzled how this has a large effect on interactivity.
> 
> Nick?

I have already got the direct data optimisation upstream. It might be
possible that it is some interaction with the extra rcu callbacks going
off... I don't know :\

-- 
SUSE Labs, Novell Inc.
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