Message-ID: <51E47BE2.3000801@linux.intel.com>
Date: Mon, 15 Jul 2013 15:46:58 -0700
From: Arjan van de Ven <arjan@linux.intel.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Morten Rasmussen <morten.rasmussen@arm.com>, mingo@kernel.org,
        vincent.guittot@linaro.org, preeti@linux.vnet.ibm.com,
        alex.shi@intel.com, efault@gmx.de, pjt@google.com, len.brown@intel.com,
        corbet@lwn.net, akpm@linux-foundation.org,
        torvalds@linux-foundation.org, tglx@linutronix.de,
        catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
        linaro-kernel@lists.linaro.org
Subject: Re: [RFC][PATCH 0/9] sched: Power scheduler design proposal
References: <1373385338-12983-1-git-send-email-morten.rasmussen@arm.com> <20130713064909.GW25631@dyad.programming.kicks-ass.net> <51E166C8.3000902@linux.intel.com> <20130715195914.GC23818@dyad.programming.kicks-ass.net> <51E45E8B.705@linux.intel.com> <20130715210650.GF23818@dyad.programming.kicks-ass.net>
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>> so depending of the mix of compute and memory instructions, different tradeoffs
>> might be needed.
>>
>> (for an example of this, AMD exposes a CPU counter for this as of recently and added
>> patches to "ondemand" to use it)
>
> OK, but isn't that part of why the micro controller might not make you go
> faster even if you do program a higher P state?
>
> But yes, I understand this issue in the 'traditional' cpufreq sense. There's no
> point in ramping the speed if all you do is stall more.
>
> But I was under the impression the 'hardware' was doing this. If not then we
> need the whole go-faster and go-slower thing and places to call them and means
> to determine to call them etc.

so the answer is "somewhat" and "on some cpus"
not all generations of Intel cpus are the same in this regard ;-(

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