Message-ID: <3F56AF70.7030009@cyberone.com.au>
Date: Thu, 04 Sep 2003 13:20:16 +1000
From: Nick Piggin <piggin@cyberone.com.au>
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To: Steven Cole <elenstev@mesatop.com>
CC: William Lee Irwin III <wli@holomorphy.com>,
       Daniel Phillips <phillips@arcor.de>,
       Antonio Vargas <wind@cocodriloo.com>, Larry McVoy <lm@bitmover.com>,
       CaT <cat@zip.com.au>, Anton Blanchard <anton@samba.org>,
       linux-kernel@vger.kernel.org
Subject: Re: Scaling noise
References: <20030903040327.GA10257@work.bitmover.com>	 <20030903124716.GE2359@wind.cocodriloo.com>	 <1062603063.1723.91.camel@spc9.esa.lanl.gov>	 <200309040350.31949.phillips@arcor.de> <1062641965.3483.78.camel@spc>	 <20030904023501.GE4306@holomorphy.com> <1062643242.3483.85.camel@spc>
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Steven Cole wrote:

>On Wed, 2003-09-03 at 20:35, William Lee Irwin III wrote:
>
>>On Wed, Sep 03, 2003 at 08:19:26PM -0600, Steven Cole wrote:
>>
>>>I would never call the SMP locking pathetic, but it could be improved.
>>>Looking at Figure 6 (Star-CD, 1-64 processors on Altix) and Figure 7
>>>(Gaussian 1-32 processors on Altix) on page 13 of "Linux Scalability for
>>>Large NUMA Systems", available for download here:
>>>http://archive.linuxsymposium.org/ols2003/Proceedings/
>>>it appears that for those applications, the curves begin to flatten
>>>rather alarmingly.  This may have little to do with locking overhead.
>>>
>>Those numbers are 2.4.x
>>
>
>Yes, I saw that.  It would be interesting to see results for recent
>2.6.0-textX kernels.  Judging from other recent numbers out of osdl, the
>results for 2.6 should be quite a bit better.  But won't the curves
>still begin to flatten, but at a higher CPU count?  Or has the miracle
>goodness of RCU pushed those limits to insanely high numbers?
>

They fixed some big 2.4 scalability problems, so it wouldn't be as
impressive as plain 2.4 -> 2.6. However there are obviously hardware
scalability limits as well as software ones. So a more interesting
comparison would of course be 2.6 vs LM's SSI clusters.


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