Re: sched: Avoid SMT siblings in select_idle_sibling() if possible

[Mike Galbraith]

On Thu, 2012-02-23 at 16:19 +0530, Srivatsa Vaddagiri wrote:

> I am seeing 2.6% _improvement_ in volanomark score by enabling SD_BALANCE_WAKE 
> at SMT/MC domains.

That's an unexpected (but welcome) result.

> Machine : 2 Quad-core Intel X5570 CPU (H/T enabled)
> Kernel  : tip (HEAD at 6241cc8)
> Java	: OpenJDK 1.6.0_20
> Volano  : 2_9_0
> 
> Volano benchmark was run 4 times with and w/o SD_BALANCE_WAKE enabled in
> SMT/MC domains.
> 
> 				Average score	std. dev
> 
> SD_BALANCE_WAKE disabled	369459.750	4825.046
> SD_BALANCE_WAKE enabled		379070.500	379070.5
> 
> I am going to try pipe benchmark next. Do you have suggestions for any other 
> benchmarks I should try to see the effect of SD_BALANCE_WAKE turned on in 
> SMT/MC domains?

Unpinned netperf TCP_RR and/or tbench pairs?  Anything that's wakeup
heavy should tell the tail.

-Mike

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