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AVX2 vs SSE4.1
#1
Hello. I read that AVX2 version of GSDx has better performance in Software Graphics mode than SSE4.1, but I wonder: if I will be using Hardware Graphics mode with AVX2, it will has the same performance as SSE4.1 or worse?

My CPU is Intel i5-4670.

Greetings,
Feliks
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#2
avx2 is to my knowledge not supported. Only AVX can be chosen. AVX2 might be supported in future versions.

For hardware rendering AVX and SSE4.1 are equal.
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#3
(05-02-2014, 10:13 AM)feliks Wrote: Hello. I read that AVX2 version of GSDx has better performance in Software Graphics mode than SSE4.1, but I wonder: if I will be using Hardware Graphics mode with AVX2, it will has the same performance as SSE4.1 or worse?

My CPU is Intel i5-4670.

Greetings,
Feliks

Both are instruction sets extensions for the CPU, actually all those MMX, SSE and such are focused in float point processing and vectors.

Besides they don't replace the other, they are added.

Just as a simple example, once upon a time many graphical functions based on multiply two numbers and then add to one the original numbers (and are very common and often used) and so many programs did it till a new instruction was incorporated in the set that did it at once and then was much more effective. Former programs multiplying and then adding continued doing so, newer programs used a simple MAD instruction to do it. Later on it was further expanded as FMA (Fuzzed Multiply Add) instructions and so on...

Many such instructions exist on GPUs also, but in the case it is meant to the CPU and can be performed only in CPUs supporting the extension, of course.

Anyway, the rule is use the more advanced if you can, nothing from the formers are lost.

Edit: In the particular case the newer instructions helped the software mode due to making the CPU more efficient treating graphics (more specifically vectors) and then those instructions were in GPUs already or couldn't be used there.
Imagination is where we are truly real
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#4
(05-02-2014, 10:13 AM)feliks Wrote: if I will be using Hardware Graphics mode with AVX2, it will has the same performance as SSE4.1 or worse?

Same performance. In HW mode, all the GSdx variants which your CPU support will perform the same.

And also in software mode the difference is very small and probably not noticeable (think maybe more 1 fps).

(05-02-2014, 02:10 PM)willkuer Wrote: avx2 is to my knowledge not supported.

It is supported.
[i7-3630qm/gt650m-2G/Win-7] [i7-4500u/R.HD8850m/Win-8.1] [2010-MBA/OSX-10.9.x]. Scroll smoothly with SmoothWheel for Firefox.
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#5
Yeah, but then there is the most common mistake of thinking the new set do anything to better old programs. To be efficient the instructions "Must" be used by the programs, conversely, compiling a program flagging it as meant for the newer set but not using any the instructions is utter stupidity since does nothing to enhance the program yet actually restricting it to be used only with newer CPUs, so, no sane developer ever do it.

Edit: Of course newer CPUs might improve things even for old implementations but this is another case and situation which does not depend on software at all.

PS: Notice that the plugins for older instructions sets are conserved, not removed, and this is because that last factor. Despite the avx2 plugin is able to use all instructions from the former sets (like SSEx) it would push out every CPU not supporting avx2... then the older ones are still needed.
Imagination is where we are truly real
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#6
(05-02-2014, 03:14 PM)avih Wrote: It is supported.

Now I see it. This is new or? Somehow missed that this was added.
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#7
It was added shortly after AVX2 CPUs became available.
[i7-3630qm/gt650m-2G/Win-7] [i7-4500u/R.HD8850m/Win-8.1] [2010-MBA/OSX-10.9.x]. Scroll smoothly with SmoothWheel for Firefox.
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