On Mon, Mar 05, 2012 at 09:39:34PM -0500, Phillip Susi wrote:
With correct frequency management, the lower power per instruction of
the lower frequencies outweighs the reduced time in the lower C
states.
This is (broadly speaking) untrue. There's a bunch of fixed costs that a
naive P=IV²
On 3/8/2012 9:47 AM, Matthew Garrett wrote:
This is (broadly speaking) untrue. There's a bunch of fixed costs that a
naive P=IV² doesn't take into account. Assuming a fixed amount of work,
race to idle is almost always the most power efficient strategy.
What fixed costs? If you spend 5
On Thu, Mar 08, 2012 at 11:03:42AM -0500, Phillip Susi wrote:
On 3/8/2012 9:47 AM, Matthew Garrett wrote:
This is (broadly speaking) untrue. There's a bunch of fixed costs that a
naive P=IV² doesn't take into account. Assuming a fixed amount of work,
race to idle is almost always the most
On 3/8/2012 11:10 AM, Matthew Garrett wrote:
Yes, if those are the actual power figures. But they're typically not
going to be.
Can you be a little less vague and hand wavy?
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On Thu, Mar 08, 2012 at 11:22:04AM -0500, Phillip Susi wrote:
On 3/8/2012 11:10 AM, Matthew Garrett wrote:
Yes, if those are the actual power figures. But they're typically not
going to be.
Can you be a little less vague and hand wavy?
My i7 draws about 7W when fully loaded at 800MHz, and
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On 03/08/2012 12:11 PM, Matthew Garrett wrote:
My i7 draws about 7W when fully loaded at 800MHz, and about 27W when
fully loaded at 2.7GHz. That's a 3.4x performance improvement at a
3.9x power increase. So, naively, that does result in a fixed
On Thu, Mar 08, 2012 at 05:29:47PM -0500, Phillip Susi wrote:
You also need to remember that 3.4x the clock speed does not mean you
actually end up finishing your work 3.4x faster. Intel recommends
using the ondemand governor, so if you are claiming they are wrong,
and you save more power
