linux-kernel - Re: [RFC PATCH 2/4] x86, mwaitt: introduce mwaitx idle with a configurable timer

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Date:	Mon, 25 May 2015 12:43:48 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Huang Rui <ray.huang@....com>
Cc:	Borislav Petkov <bp@...e.de>, Len Brown <lenb@...nel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Aaron Lu <aaron.lu@...el.com>, "Li, Tony" <Tony.Li@....com>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [RFC PATCH 2/4] x86, mwaitt: introduce mwaitx idle with a
 configurable timer


* Huang Rui <ray.huang@....com> wrote:

> No, the timeout value doesn't decide how 'deep' the power state 
> enters. Basically, the same power consumption with any timeout.
> 
> I summarized the comparison of mwait and mwaitx
> 
>                 MWAIT                           MWAITX
> opcode          0f 01 c9           |            0f 01 fb
> ECX[0]                  value of RFLAGS.IF seen by instruction
> ECX[1]          unused/#GP if set  |            enable timer if set
> ECX[31:2]                     unused/#GP if set
> EAX                             unused
> EBX[31:0]       unused             |            max wait time (loops)
> 
> 
>                 MONITOR                         MONITORX
> opcode          0f 01 c8           |            0f 01 fa
> EAX                     (logical) address to monitor
> ECX                     #GP if not zero

Ok, thanks for the clarification!

Thanks,

	Ingo
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