Re: [PATCH V2] perf: x86: Improve accuracy of perf/sched clock

[Peter Zijlstra]

On Mon, Aug 17, 2015 at 10:34:03AM +0300, Adrian Hunter wrote:
> On 29/07/15 00:14, Adrian Hunter wrote:
> > When TSC is stable perf/sched clock is based on it.
> > However the conversion from cycles to nanoseconds
> > is not as accurate as it could be.  Because
> > CYC2NS_SCALE_FACTOR is 10, the accuracy is +/- 1/2048
> > 
> > The change is to calculate the maximum shift that
> > results in a multiplier that is still a 32-bit number.
> > For example all frequencies over 1 GHz will have
> > a shift of 32, making the accuracy of the conversion
> > +/- 1/(2^33)
> > 
> > Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> 
> Is this OK?

Yes I think so, sorry I got backlogged with preparation for Seattle.

Thomas, if you see this, could you merge with my ACK on, otherwise I'll
queue it the normal route once I'm back.
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