Re: -warmup

[chris]

On Fri, 18 Aug 2023 11:02:49 +0000 (UTC), Werner LEMBERG wrote:
> To summarize: Benchmark comparisons only work if there is a sound
> mathematical foundation to reduce the noise.

I am probably not qualified, but I am following the discussion for some 
time. And I think there is a problem with the benchmarking itself. If I 
understand correctly the nice tables show the same code on the same 
machine so 40% difference or so is not ok.

I had a quick look at ftbench.c and I have the impression that the 
timer ist using by clock_gettime for every single iteration twice. I 
had expected to do N iterations with a single clock_gettime before and 
after N iterations. If the benchmarked code is short this will 
accumulate errors that cannot be removed afterwards. But I may be 
wrong...

Greetings, chris