It is not Moblin, but standard linux kernel which doesn't provide user interface to force CPU into Cx state other than C0. From my point of view, this interface is totally meaningless because Cx>C0 means CPU stop working. Even you can force CPU into some C state, external interrupt will wakeup the CPU immediately, or system will fall into a mess. It is kernel who well knows when CPU can be put into some Cx state safely and how long it will stay based on complex calculation. For user, it is impossible to know it. If you'd like measure power consumption when system is in idle, just let it go. Even put system into S3 state is a bit more make sense.
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Smart Yang Sent: 2009年9月16日 14:55 To: Zhang, Austin; [email protected]; [email protected] Subject: Re: [Moblin Dev] low power state of atom Hi Austin, We can make or modify some driver to "setting" CPU into some state. And the whole process need no intervention from user mode. We want to know whether moblin has some low level interface or driver which can make CPU enter some power state. And we can invoke them to set CPU state which is most like deciding by OS as you mentioned. Message: 9 Date: Wed, 16 Sep 2009 14:41:59 +0800 From: "Zhang, Austin" <[email protected]> To: ??? <[email protected]>, Arjan van de Ven <[email protected]> Cc: dev <[email protected]> Subject: Re: [Moblin Dev] low power state of atom Message-ID: <38d9f46dff92c54980d2f2c1e8ee313001ab921...@pdsmsx503.ccr.corp.intel.com> Content-Type: text/plain; charset="gb2312" > how can we get this tool.so we can exactly know which C and P states the system using. > then, > how can we set the CPU into Deeper sleep?like pxa270?we can change cpu mode by writting cp15 register > > we check the datasheet of both z5xx and SCH(us15wx) ,but find no description of how can we generate the signals which can force CPU enter Deeper sleep. Why not google :) http://www.lesswatts.org/projects/powertop/ Again, like arjan said, when you are trying to 'setting' it, that means your cpu is working, so at this kind of situation, you CAN NOT enter into deep c because cpu is working to your task. Please let OS/CPU decide when and which level it should go to rather than 'setting' it. > my purpose is to check the cpu Actual power loss when cpu work in Deeper sleep(C4)?or Deep power down(C6)?. Maybe you should use some physical device like power meter rather than by 'setting something and check it' for this purpose. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ??? Sent: Wednesday, September 16, 2009 2:20 PM To: Arjan van de Ven Cc: dev Subject: Re: [Moblin Dev] low power state of atom Hi? thanks for your answer? first? ?I suspect that your system WILL go into C4. If you are not sure, you can run the powertop tool,?how can we get this tool.so we can exactly know which C and P states the system using. then, how can we set the CPU into Deeper sleep?like pxa270?we can change cpu mode by writting cp15 register we check the datasheet of both z5xx and SCH(us15wx) ,but find no description of how can we generate the signals which can force CPU enter Deeper sleep. _______________________________________________ Moblin dev Mailing List [email protected] To manage or unsubscribe from this mailing list visit: http://lists.moblin.org/listinfo/dev or your user account on http://moblin.org once logged in. For more information on the Moblin Developer Mailing lists visit: http://moblin.org/community/mailing-lists _______________________________________________ Moblin dev Mailing List [email protected] To manage or unsubscribe from this mailing list visit: http://lists.moblin.org/listinfo/dev or your user account on http://moblin.org once logged in. For more information on the Moblin Developer Mailing lists visit: http://moblin.org/community/mailing-lists
