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From: Thomas Gleixner <tglx@linutronix.de>
To: Bin Gao <bin.gao@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	John Stultz <john.stultz@linaro.org>,
	Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org, bin.gao@intel.com
Subject: Re: [PATCH v2] x86/tsc: Set X86_FEATURE_TSC_RELIABLE to skip refined calibration
Date: Wed, 12 Oct 2016 09:52:34 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1610120948250.5032@nanos> (raw)
In-Reply-To: <20161011211121.GA15041@worksta>

On Tue, 11 Oct 2016, Bin Gao wrote:
> On Fri, Aug 26, 2016 at 12:14:58PM +0200, Thomas Gleixner wrote:
> 
> The Linux kernel does think a reliable calibration implies the reliability (i.e.
> no watchdog required). I'm posting some code pieces to explain.

I know that and I know exactly how all that works. And I certainly did not
ask for an explanation of the current state of affairs. Here is what I
wrote:

> > Second thoughts. We should seperate the calibration aspect from the reliablity
> > aspect.
> > 
> > If a MSR/CPUID readout provides reliable calibration then this does not tell
> > us about the reliablity (i.e. no watchdog required). So having two flags for
> > this - and sure you can set both on those SoCs is the proper solution.

In other words: I want to have two seperate flags:

1) FEATURE_KNOWN_FREQUENCY     - Grab the frequency from CPUID/MSR or whatever
   			       	 and skip the whole calibration thing

2) FEATURE_RELIABLE	       - Do not invoke the watchdog

Thanks,

	tglx
     



 

  reply	other threads:[~2016-10-12  7:56 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-16 17:42 Bin Gao
2016-08-24  8:51 ` Thomas Gleixner
2016-08-25 16:43   ` Bin Gao
2016-08-26 10:11     ` Thomas Gleixner
2016-08-26 10:14       ` Thomas Gleixner
2016-10-11 21:11         ` Bin Gao
2016-10-12  7:52           ` Thomas Gleixner [this message]
2016-10-13 23:16             ` [PATCH v3] x86/tsc: add X86_FEATURE_TSC_KNOWN_FREQ flag Bin Gao
2016-10-20  9:57               ` Thomas Gleixner
2016-10-20 10:17                 ` Peter Zijlstra
2016-10-20 19:37                   ` Thomas Gleixner
2016-10-21  5:47                     ` Peter Zijlstra
2016-10-21  8:05                       ` Thomas Gleixner

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