Re: 2.6.19-rt14 slowdown compared to 2.6.19

[K.R. Foley]

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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