Messages in this thread | | | Date | Tue, 2 Jun 2015 17:39:38 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH RFC] x86, tsc: Allow for high latency in quick_pit_calibrate() |
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On Tue, Jun 02, 2015 at 05:21:27PM -0700, Andy Lutomirski wrote: > On Tue, Jun 2, 2015 at 4:38 PM, Andi Kleen <ak@linux.intel.com> wrote: > > 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. > > > > tglx's suggestion was to use slow calibration as a fallback.
You mean the last fallback we have today?
That one doesn't work if the PIT read is too slow.
And Adrian's patch is fixing that.
-Andi
-- ak@linux.intel.com -- Speaking for myself only
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