Comment by menaerus
1 year ago
Yes, you're correct that your CPU has 8 CCDs but the bw with 8 threads is already too low. Those 8 cores should be able to get you at roughly half of the theoretical bw. 8x zen5 cores for comparison can reach the ~230 GB/s mark.
Can you repeat the same lkwid experiment but with 1, 2 and 4 threads? I'm wondering when is it that it begins to detoriate quickly.
Maybe also worth doing is repeating the 8 threads but forcing lkwid to pick every third physical core so that you get 1 thread per CCD experiment setting.
1: 33586.74 2: 47371.93 4: 65870.07
With `likwid-bench -i 100 -t load -w M0:5GB:1 -w M1:5GB:1 -w M2:5GB:1 -w M3:5GB:1 -w M4:5GB:1 -w M5:5GB:1 -w M6:5GB:1 -w M7:5GB:1` we get 187976.60
Obvious there's a bottleneck either going on somewhere - at 33.5GB/s per channel, that would get close to 400GB/s, what you'd expect, but the reality is that it doesn't get to half of that. Bad MC? Bottleneck w/ the MB? Hard to tell, not sure that without swapping hardware there's much more that can be done to diagnose things.
Mixed results. I suspect you might have an ES (engineering sample) of your CPU.
Besides not having ES markings, It is a retail serial and stepping in dmidecode, so that's unlikely.
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