Ryzen 2 and BMI2?

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Gian-Carlo Pascutto
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Re: Ryzen 2 and BMI2?

Post by Gian-Carlo Pascutto » Wed May 16, 2018 12:35 pm

syzygy wrote:
Tue May 15, 2018 11:08 pm
Did Crafty as included in SPEC CPU2000 not use any of those on platforms where they were available? (Probably not, I guess...)
You have to ask Bob (I don't have a SPEC2000 license) but it's hard to imagine that non-Intel and non-AMD SPEC members wouldn't object to that. Using generic intrinsics like those of GCC (builtin_ffs or what's it called) doesn't work either because it needs to be compilable by pretty much every ages old proprietary compiler out there too.
Apparently SPEC CPU2017 not includes Deep Sjeng but also Leela. Nice :)
Yeah. I regret that SPEC CPU2017 allows parallelism in "speed" benchmarks though (even if only xz uses it). But it's an impossible situation given increasing core counts and how boost speeds influence these benchmarks.

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Re: Ryzen 2 and BMI2?

Post by yurikvelo » Mon May 18, 2020 7:59 am

Still true for Zen 2.
BMI2 compiles are much slower than POPCNT

Joost Buijs
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Re: Ryzen 2 and BMI2?

Post by Joost Buijs » Mon May 18, 2020 9:27 am

yurikvelo wrote:
Mon May 18, 2020 7:59 am
Still true for Zen 2.
BMI2 compiles are much slower than POPCNT
I'm still waiting for the Intel 10980XE that I want to use for a new workstation, in the mean time I bought an AMD 3970X because I didn't want to wait any longer. It's a nice processor as long as you don't overclock it with precision boost (otherwise it runs extremely hot), PEXT and PDEP are unusable, maybe even worse as Zen 1. I tried to emulate PEXT in software and that runs faster as the native CPU instruction. AVX2 on the AMD is slow too, and it misses AVX-512.

Maybe scatter-gather is not so important for a chess engine, but there are other applications in which it is very useful.

I will keep the AMD 3970X for bulk applications, but as soon as the 10980XE is readily available I will use that one for a new workstation.

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