Simplify and improve x86/amd64 CPU build flags

[raymond]

regarding ticket #2329

http://trac.wildfiregames.com/ticket/2329

It is better to make core2 flag as default?

Why not: "‘core2’
Intel Core 2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support."

Maybe "SSE2, SSE3 and SSSE" (in core2) improve the performance?
(​https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/i386-and-x86-64-Options.html#i386-and-x86-64-Options)

Pentium III last produced until 2002.
Note: SSE II support: 99 %; SSE III support: 95% (​http://feedback.wildfiregames.com/static/cpucaps.html)

So increasing the requirements to Core2Duo CPU is not a problem.

Edited May 19, 2014 by raymond

[fabio]

No numbers for the change at hand now, but the performance changes of that commit should be very small. You can try it yourself with:

./pyrogenesis -replay=/path/to/commands.txt

I used pentium3 because it just matches what was previously used (sse, which first appeared on p3).

Note that core2 also requires SSSE3, only supported by 64.7% (I am using a CoreDuo myself, so Core2 won't work here).

Eventually we could force a minimum newer CPU (pentium-m or pentium4), losing (unless they change the default build flag) about 1-5% users (which IMO are too many, anyway) if there are clear performance advantages.

Also keep in mind that on x86-64 (which is used by most Linux users) the minimum supported CPU is already a much newer CPU (core2 like).

[raymond]

Good compromise to use pentium-m or pentium4 optimization. Maybe test it for performance advantages against optimization "pentium3".

Edited May 19, 2014 by raymond

[Josh]

There was some testing awhile ago, and if I remember correctly, the improvements by optimizing the build flags were within the margin of error.

[raymond]

No numbers for the change at hand now, but the performance changes of that commit should be very small. You can try it yourself with:

./pyrogenesis -replay=/path/to/commands.txt

I used pentium3 because it just matches what was previously used (sse, which first appeared on p3).

Note that core2 also requires SSSE3, only supported by 64.7% (I am using a CoreDuo myself, so Core2 won't work here).

Eventually we could force a minimum newer CPU (pentium-m or pentium4), losing (unless they change the default build flag) about 1-5% users (which IMO are too many, anyway) if there are clear performance advantages.

Also keep in mind that on x86-64 (which is used by most Linux users) the minimum supported CPU is already a much newer CPU (core2 like).

I checked http://feedback.wildfiregames.com/static/cpucaps.html again: SSSE3 is now at 80.2%. Maybe at the end of the development process for A17 you could enable core2duo support as minimum?

No intention for you to upgrade to a minimum Core2Duo system? A Core2Duo system (or a cheap Core i3) are really cheap today

Edited July 9, 2014 by raymond

[raymond]

The stats at http://feedback.wildfiregames.com/static/cpucaps.html (could anyone trigger to update it?!)

"Based on data submitted by players of 0 A.D. from 2014-01-01 to 2014-07-01"

So I think there are not so many Pentium 3 users now. There are also 96.4% of users, who used a x86-64 processor.

Edited January 5, 2016 by raymond