Stockfish much slower on windows 8 than on windows 10 for me

[FireTea]

Triple boot with Windows 8, Windows 10 and Linux showed that an old Windows 8 Stockfish 12 (as well as 11 and most likely other versions of the engine) was about 25% slower (no matter if using 1, 8 or 16 threads) on my amd Ryzen 1700. So exactly the same hardware.

I was expecting perhaps some slight penalty in the opposite direction due to spectre fixes in the Windows 10 version but I see no reason for this result. Large pages are off in both cases.

Any ideas? Could it be due to an old Windows 8 installation missing some instructions useful for Ryzen cpu?

I did not use the bmi versions of the engine since Ryzen implements these instruction sets in software...

[nabildanial]

Triple boot with Windows 8, Windows 10 and Linux showed that an old Windows 8 Stockfish 12 (as well as 11 and most likely other versions of the engine) was about 25% slower (no matter if using 1, 8 or 16 threads) on my amd Ryzen 1700. So exactly the same hardware.

I was expecting perhaps some slight penalty in the opposite direction due to spectre fixes in the Windows 10 version but I see no reason for this result. Large pages are off in both cases.

Any ideas? Could it be due to an old Windows 8 installation missing some instructions useful for Ryzen cpu?

I did not use the bmi versions of the engine since Ryzen implements these instruction sets in software...

This probably the reason for the speedup.

[FireTea]

Triple boot with Windows 8, Windows 10 and Linux showed that an old Windows 8 Stockfish 12 (as well as 11 and most likely other versions of the engine) was about 25% slower (no matter if using 1, 8 or 16 threads) on my amd Ryzen 1700. So exactly the same hardware.

I was expecting perhaps some slight penalty in the opposite direction due to spectre fixes in the Windows 10 version but I see no reason for this result. Large pages are off in both cases.

Any ideas? Could it be due to an old Windows 8 installation missing some instructions useful for Ryzen cpu?

I did not use the bmi versions of the engine since Ryzen implements these instruction sets in software...

This probably the reason for the speedup.

Thank you, that seems reasonable! Had never heard about that...