From: Borislav Petkov <bp@alien8.de>
To: Huang Rui <ray.huang@amd.com>
Cc: Len Brown <lenb@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-kernel@vger.kernel.org,
Fengguang Wu <fengguang.wu@intel.com>,
Aaron Lu <aaron.lu@intel.com>, Tony Li <tony.li@amd.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Mwait usage on AMD processors
Date: Thu, 14 May 2015 16:20:51 +0200 [thread overview]
Message-ID: <20150514142051.GD29125@pd.tnic> (raw)
In-Reply-To: <20150514133857.GB6552@hr-slim.amd.com>
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.
--
next prev parent reply other threads:[~2015-05-14 14:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-14 6:54 Mwait usage on AMD processors Huang Rui
2015-05-14 9:21 ` Borislav Petkov
2015-05-14 10:17 ` Huang Rui
2015-05-14 11:23 ` Borislav Petkov
2015-05-14 13:38 ` Huang Rui
2015-05-14 14:20 ` Borislav Petkov [this message]
2015-05-19 7:25 ` Huang Rui
2015-05-19 8:50 ` Borislav Petkov
2015-05-19 9:42 ` Huang Rui
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