Kaitlin Murphy of Intel(r) on the Atom processor’s power management capabilities
August 8th, 2008Last week’s webinar left off with several questions from the participants. I answered mine in an earlier post. My collaborator Kaitlin Murphy has provided answers to the hardware questions. Courtesy of Intel and Kaitlin I was permitted to post her answers here:
Q: What kind of power benefit we can gain by entering C6 of Atom CPU?
In the C6 state, the Intel(r) Atom processor will consume approximately 6% of the power it would consume in the C0 state. This roughly correlates to 100 mW, although the exact value may vary depending on which SKU of the processor is used and other factors. Obviously, the more time the Intel(r) Atom processor spends in the C6 state (or any other sleep state), the more power savings will be realized.
Q: What is the typical power consumption on a MID device using Atom on C0 and C6?
The power consumption of the Intel(r) Atom processor will vary significantly by usage conditions. For the MID type application, the average power is 160 - 220 mW, with ~100 mW idle power. (Idle and Average Power power quoted is using a mean leakage CPU which means that 50% of the CPUs will have leakage values below the median value and 50% will have leakage values above the median.) These numbers will differ in an embedded use case.
Q: Is it possible to disable part of the chipset (in our case, no video needed).
On the Intel(r) System Controller Hub US15W, it is possible to effectively disable the graphics core via clock gating. Intel does offer other “headless” products - such as the Intel(r) EP80579 which may work for your application, depending on your needs.
Q: …can [you] give me a [watt per MHZ] value?
This will be SKU dependant. For the Intel(r) Atom Z530 SKU at 1.6 GHz, the TDP is 2.2 W. Therefore, your theoretical W/MHz value is ~727 MHz/W. A similar calculation applied to the Z510 SKU yields ~550 MHz/W.
Q: How much as a percentage does the SpeedStep technology help if I have a real time application and cannot go to the lowest C state?
Intel(r) Enhanced Speed Step Technology can still be a big asset in power savings and power management - even if you can’t go into the lowest C state(s). The amount of time a processor can spend in a lower sleep state is primarily dependant on what it has been tasked to do. There is no reason a processor can’t handle real time requests when operating at a frequency lower than HFM. In fact, I’ve seen customers de-rate a processor (essentially forcing it to run at a lower frequency, simulating SpeedStep) if lower power consumption is a requirement.
Again: A big thank you to Kaitlin, Intel, and all of our participants.
