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Message-ID: <alpine.DEB.2.11.1505212128250.31710@nanos>
Date: Thu, 21 May 2015 21:30:16 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Borislav Petkov <bp@...e.de>
cc: Huang Rui <ray.huang@....com>,
One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
Ingo Molnar <mingo@...nel.org>, Len Brown <lenb@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"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>,
Frédéric Weisbecker <fweisbec@...il.com>,
Andy Lutomirski <luto@...capital.net>
Subject: Re: [RFC PATCH 2/4] x86, mwaitt: introduce mwaitx idle with a
configurable timer
On Thu, 21 May 2015, Borislav Petkov wrote:
> On Thu, May 21, 2015 at 10:56:32PM +0800, Huang Rui wrote:
> > Looks like good use case. Boris, could we try to implement it?
>
> Andy had some suggestions on how to do it here:
>
> https://lkml.kernel.org/r/555D3629.8080002@kernel.org
>
> which should be doable. Also, you'd probably need to set ECX[0]=0b too,
> so that MWAITX doesn't get woken up by interrupts while MWAIT-ing with
> interrupts disabled. I.e., this sequence:
>
> cli
> rdtsc
> shove the computed timeout into ebx
> mov $2,%ecx # this enables the timer and disables IRQs while MWAITing
> mwaitx
> sti
And the above sucks for udelay, because you disable interrupts for
random amounts of time.
Thanks,
tglx
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