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On 9/18/20 8:21 PM, jr wrote:
> "jr" <cre### [at] gmail com> wrote:
...
>
> no sleep. :-( so, if you (WFP)/anyone is interested, I can add to the ..
> mystery.
>
> I have the same alpha.10064268 installed on two machines, and I mean the same.
> both built from the same tarball using nearly identical package build scripts.
> on one machine, as posted, I see a decrease in time by (just) better than 50%
> for the coloured background. on the other, the alpha behaves as you describe,
> time up from seconds to over a quarter of an hour. wow. I also tried two older
> 3.8.0-alphas (9893777 and 9945627) on a third box, they too run faster by around
> 50% when colour is used. one thing I noticed is that where time decreases, on
> the older boxes, the "CPU detected" reads "Intel,SSE2,AVX", whereas for the ..
> misbehaving alpha (newer box) it's "Intel,SSE,AVX,AVX2,FMA3". no idea whether
> that is relevant, still, it'd be interesting to know what CPU flags others see.
> anyway, as Kenneth intimated, computing, eh? -- all good fun.
>
>
Jim, and all thanks for the data. And jr, especially, for picking up the
"Intel,SSE,AVX,AVX2,FMA3" bit. It is what I see here for run time
optimization. I've hit a few other cases where - for whatever reasons -
that run time CPU optimization isn't faster for me, though usually it
is. Nothing previously was anywhere as dramatic a slow down.
I've never looked over Christoph's am3 code. Guess I'll go take a peek.
Bill P.
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