Bmi2 and AMD

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Leo
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Bmi2 and AMD

Post by Leo » Thu May 21, 2020 3:51 pm

Do we know if AMD has has fixed its Bmi2 problems?
Advanced Micro Devices fan.

MonteCarlo
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Re: Bmi2 and AMD

Post by MonteCarlo » Thu May 21, 2020 4:27 pm

There was a recent update of an old thread viewtopic.php?f=7&t=67432 that suggested there is no improvement.

I'm also not aware of any improvements, but I only follow these things loosely, so take with a grain of salt :)

Dann Corbit
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Re: Bmi2 and AMD

Post by Dann Corbit » Thu May 21, 2020 5:03 pm

Compile for modern. A BMI compile on AMD is bad. Look at the BMI compiles here:
http://ipmanchess.yolasite.com/amd---in ... -bench.php
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yurikvelo
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Re: Bmi2 and AMD

Post by yurikvelo » Thu May 21, 2020 5:18 pm

Zen3 promise 10-15% IPC improvement.
Maybe they will implement hardware BMI2 execution as a part of this 10-15% target

AVX-512 is set to be only in Zen4 (along with DDR5)

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yurikvelo
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Re: Bmi2 and AMD

Post by yurikvelo » Thu May 21, 2020 10:40 pm

Fishtest run BMI2 compiles for all AMD CPU with BMI2 support.
make ARCH=x86-64-bmi2

It's not good.

Leo
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Re: Bmi2 and AMD

Post by Leo » Fri May 22, 2020 2:39 am

MonteCarlo wrote:
Thu May 21, 2020 4:27 pm
There was a recent update of an old thread viewtopic.php?f=7&t=67432 that suggested there is no improvement.

I'm also not aware of any improvements, but I only follow these things loosely, so take with a grain of salt :)
Thanks.
Advanced Micro Devices fan.

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