linux-kernel - Re: [PATCH v6 2/2] x86, mwaitt: introduce mwaitx delay with a configurable timer

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Message-ID: <20150807044636.GB7607@hr-slim.amd.com>
Date:	Fri, 7 Aug 2015 12:46:37 +0800
From:	Huang Rui <ray.huang@....com>
To:	Borislav Petkov <bp@...e.de>
CC:	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	John Stultz <john.stultz@...aro.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	<linux-kernel@...r.kernel.org>, <x86@...nel.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Aaron Lu <aaron.lu@...el.com>, Tony Li <tony.li@....com>,
	Andreas Herrmann <herrmann.der.user@...il.com>
Subject: Re: [PATCH v6 2/2] x86, mwaitt: introduce mwaitx delay with a
 configurable timer

On Thu, Aug 06, 2015 at 05:14:40PM +0200, Borislav Petkov wrote:
> On Wed, Aug 05, 2015 at 11:18:52AM +0800, Huang Rui wrote:
> > +static void delay_mwaitx(unsigned long __loops)
> > +{
> > +	u32 delay, loops = __loops;
> > +	u64 end, start;
> 
> Hmm, this truncates __loops in case someone wants to delay for more
> than (u32)-1 TSC clocks. I guess the right thing to do is to do the
> calculation with u64s and MWAITX_MAX_LOOPS will keep us within bounds.
> 

Yes, you're right. Thanks to update. :)

Thanks,
Rui
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