Messages in this thread | | | Date | Tue, 19 May 2015 10:50:17 +0200 | From | Borislav Petkov <> | Subject | Re: Mwait usage on AMD processors |
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On Tue, May 19, 2015 at 03:25:53PM +0800, Huang Rui wrote: > Apology that cause to misunderstand. It's not as same as intel. > Intel is able to go to C1E like you said, the C1E has less power > consumption than C1 on Intel platform.
You still misunderstand - I'm not talking about Intel platforms here but AMD ones. On AMD we never enter idle with MWAIT - we do HLT which enters C1 and then the hw enters C1E when a bunch of conditions are fulfilled.
> The faster waiting exit speed. But it's hard to test the improvement, > do you have any idea? It's told by HW designer.
You can test the improvement with a special setup only. Unless you can read out power consumption of a box while it is idle.
The exit-idle speed only does not suffice to switch to MWAIT though, IMHO. I think power consumption in idle should be the relevant metric here.
> Current CPU, power consumption cannot go to deeper low power state > (C1) via mwaitx/mwait. But HW designers will implement it in future > processors.
So future CPUs we will switch to MWAIT. I don't see a problem with that.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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