How is GHz days computed?

[ATH]

My 5960X 8-core running at 3.5 Ghz should roughly give 8*3.5 = 28 Ghz-days per day.

Actually it completes an LL test giving ~ 215 Ghz-days in roughly 60 hours = 2.5 days:
215/2.5 = 86 Ghz-days per day, so 3x more than the simple calculation.


Ghz-days is just a measure for a certain amount of TFLOP (not FLOPS). A rough estimate of how many TFLOP each test takes at each FFT level.

We found out in this thread: http://mersenneforum.org/showthread.php?t=22745
that 1 Ghz-day = 172.8 TFLOP, which is the amount an old Core2 processor could do on 1 core running at 1 Ghz in 1 day.

Since new processors can do more TFLOP per Ghz due to AVX, AVX2/FMA it would make more sense to switch everything to TFLOP or PFLOP.

[kladner]

Originally Posted by daxmick

Alas, it appears there is no "back of the envelope" way for a layman, such as myself, to pre-calculate my GHz-days. Oh well. I'll just watch the https://www.mersenne.org/cpus/ page for my CPUs and see what they return.

Thank you to everyone for your patience in getting this concept through my thick skull.

There is a Ghz days per day calculator for CPUs here:
http://www.mersenne.ca/throughput.php
For GPUs doing mfaktc Trial Factoring:
http://www.mersenne.ca/mfaktc.php
For GPUs running LL testing via CUDALucas:
http://www.mersenne.ca/cudalucas.php