Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate()

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From	Andi Kleen <ak@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate()
Date	Wed, 03 Jun 2015 01:40:01 +0200
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X-Original-Cc	Andy Lutomirski <luto@amacapital.net>, Adrian Hunter <adrian.hunter@intel.com>, LKML <linux-kernel@vger.kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Len Brown <lenb@kernel.org>
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On Tue, Jun 02, 2015 at 11:03:26PM +0200, Thomas Gleixner wrote:
> 
> 
> On Tue, 2 Jun 2015, Andi Kleen wrote:
> 
> > > There's the code in tsc_msr.c.  It should be relatively
> > > straightforward to extend it to cover everything that intel_pstate
> > > supports.
> > 
> > That's a good idea, but we still need an always working fallback when the
> > model number is not available. So Adrian's patch is needed in any
> > case.
>  
> Nonsense. The slow calibration is already a working fallback.

Please read Adrian's description again. It's not working when the PIT read is
too slow. That is when the new algorithm is needed.

-Andi
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Re: [PATCH RFC] x86, tsc: Allow for high latency in  quick_pit_calibrate() Andi Kleen <ak@linux.intel.com> - 2015-06-03 01:40 +0200
  Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate() Andy Lutomirski <luto@amacapital.net> - 2015-06-03 02:30 +0200
    Re: [PATCH RFC] x86, tsc: Allow for high latency in  quick_pit_calibrate() Andi Kleen <ak@linux.intel.com> - 2015-06-03 02:50 +0200
      Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate() Andy Lutomirski <luto@amacapital.net> - 2015-06-03 03:00 +0200
        Re: [PATCH RFC] x86, tsc: Allow for high latency in  quick_pit_calibrate() Thomas Gleixner <tglx@linutronix.de> - 2015-06-03 18:30 +0200
        Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate() Adrian Hunter <adrian.hunter@intel.com> - 2015-06-04 13:40 +0200

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