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Date: Thu, 14 May 2015 16:20:51 +0200 From: Borislav Petkov <bp@...en8.de> To: Huang Rui <ray.huang@....com> Cc: Len Brown <lenb@...nel.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-kernel@...r.kernel.org, Fengguang Wu <fengguang.wu@...el.com>, Aaron Lu <aaron.lu@...el.com>, Tony Li <tony.li@....com>, Thomas Gleixner <tglx@...utronix.de> Subject: Re: Mwait usage on AMD processors On Thu, May 14, 2015 at 09:38:57PM +0800, Huang Rui wrote: > Is C1E here you mentioned is waiting state that use mwaitx enters at > AMD platform? If yes, please see below comments: > > Current processor: > Power saving: C0 < C1E (AMD) < C1 How is C1 > C1E ? C1E is the Enhanced C1. > Performance: Halt < Mwait <= Mwaitx What performance? You're idle. > Halt -> C1, and Mwaitx/Mwait -> C1E (AMD) Huh? Right now we do HLT on all AMD and the hw enters C1E after a bunch of stuff is fulfilled first. Are the plans to enter C1E from MWAIT now? > Consider about the balance between power consumption and performance, > so we want to expose the interface. And mwaitx has different opcode > with traditional mwait. There's alternative()'s for that. > Due to C1E (AMD) less power saving that real C1, so you can think it > still in C0 at current. Which CPUs, current or upcoming? If you want to do MWAITX for upcoming CPUs, simply define your own idle routine and select it in select_idle_routine(). > In furture processor: > HW designer would do Mwaitx -> C1 or deeper low power state. > > BTW, could I expose it and send the patches to review? You can always send out the patches, sure. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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