lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150514142051.GD29125@pd.tnic>
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ