Message-ID: <458C97ED.4000904@cybsft.com>
Date: Fri, 22 Dec 2006 20:43:57 -0600
From: "K.R. Foley" <kr@cybsft.com>
Organization: Cybersoft Solutions, Inc.
User-Agent: Thunderbird 1.5.0.9 (X11/20061206)
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To: "Chen, Tim C" <tim.c.chen@intel.com>
CC: mingo@elte.hu, linux-kernel@vger.kernel.org,
       "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Subject: Re: 2.6.19-rt14 slowdown compared to 2.6.19
References: <9D2C22909C6E774EBFB8B5583AE5291C0199950A@fmsmsx414.amr.corp.intel.com>
In-Reply-To: <9D2C22909C6E774EBFB8B5583AE5291C0199950A@fmsmsx414.amr.corp.intel.com>
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Chen, Tim C wrote:
> Ingo,
>  
> We did some benchmarking on 2.6.19-rt14, compared it with 2.6.19 
> kernel and noticed several slowdowns.  The test machine is a 2 socket
> woodcrest machine with your default configuration.
>  
> Netperf TCP Streaming was slower by 40% ( 1 server and 1 client 
> each bound to separate cpu cores on different socket, network
> loopback mode was used).  
> 
> Volanomark was slower by 80% (Server and Clients communicate with 
> network loopback mode. Idle time goes from 1% to 60%)
> 
> Re-Aim7 was slower by 40% (idle time goes from 0% to 20%)
> 
> Wonder if you have any suggestions on what could cause the slowdown.  
> We've tried disabling CONFIG_NO_HZ and it didn't help much.
>
> Thanks.
> 
> Tim

Take a look at this. Not sure if this is the same problem but it looks
like a candidate. I can definitely say that some latencies I have seen
in my recent testing have gone away in the last few versions
2.6.20-rc1-rt{3,4}.

-- 
	kr
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