Date:	Mon, 15 Apr 2013 14:04:09 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Len Brown <lenb@...nel.org>, mingo@...hat.com,
	peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, pjt@...gle.com,
	namhyung@...nel.org, efault@....de, morten.rasmussen@....com,
	vincent.guittot@...aro.org, gregkh@...uxfoundation.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, len.brown@...el.com,
	rafael.j.wysocki@...el.com, jkosina@...e.cz,
	clark.williams@...il.com, tony.luck@...el.com,
	keescook@...omium.org, mgorman@...e.de, riel@...hat.com,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [patch v7 0/21] sched: power aware scheduling

On 04/14/2013 11:59 PM, Borislav Petkov wrote:
> On Sun, Apr 14, 2013 at 09:28:50AM +0800, Alex Shi wrote:
>> Even some scenario the total energy cost more, at least the avg watts
>> dropped in that scenarios.
> 
> Ok, what's wrong with x = 32 then? So basically if you're looking at
> avg watts, you don't want to have more than 16 threads, otherwise
> powersaving sucks on that particular uarch and platform. Can you say
> that for all platforms out there?

The cpu freq boost make the avg watts higher with x = 32, and also make
higher power efficiency. We can disable cpu freq boost for this if we
want lower power consumption all time.
But for my understanding, the power efficient is better way to save power.
As to other platforms, I'm glad to see any testing or try and give me
results...
> 
> Also, I've added in the columns below the Energy = Power * Time thing.

Thanks. btw the third data of each column is 'performance/watt'. that
shows similar meaning on the other side. :)
> 
> And the funny thing is, exactly there where avg watts is better in
> powersaving, energy for workload retire is worse. And the other way
> around. Basically, avg watts vs retire energy is reciprocal. Great :-\.
> 
>> Len said he has low p-state which can work there. but that's is
>> different. I had sent some data in another email list to show the
>> difference:
>>
>> The following is 2 times kbuild testing result for 3 kinds condiation on
>> SNB EP box, the middle column is the lowest p-state testing result, we
>> can see, it has the lowest power consumption, also has the lowest
>> performance/watts value.
>> At least for kbuild benchmark, powersaving policy has the best
>> compromise on powersaving and power efficient. Further more, due to cpu
>> boost feature, it has better performance in some scenarios.
>>
>>    powersaving + ondemand  userspace + fixed 1.2GHz performance+ondemand
>> x = 8    231.318 /75 57           165.063 /166 36        253.552 /63 62
>> x = 16   280.357 /49 72           174.408 /106 54        296.776 /41 82
>> x = 32   325.206 /34 90           178.675 /90 62         314.153 /37 86
>>
>> x = 8    233.623 /74 57           164.507 /168 36        254.775 /65 60
>> x = 16   272.54  /38 96           174.364 /106 54        297.731 /42 79
>> x = 32   320.758 /34 91           177.917 /91 61         317.875 /35 89
>> x = 64   326.837 /33 92           179.037 /90 62         320.615 /36 86
> 
> 	    17348.850		    27400.458		   15973.776
> 	    13737.493		    18487.248		   12167.816
> 	    11057.004		    16080.750		   11623.661
> 
> 	    17288.102		    27637.176		   16560.375
> 	    10356.52		    18482.584		   12504.702
> 	    10905.772		    16190.447		   11125.625
> 	    10785.621		    16113.330		   11542.140
> 


-- 
Thanks Alex
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