array performance / direct memory access?

Gillian · 2014-03-05T01:44:17

After playing quite a bit with angelscript lately, I have noticed that accessing array elements is pretty costly: I am trying to write some data processing algorithms using anglescript, and it is pretty fast, except when accessing array elements. For data intensive algorithms, that's unfortunately not ideal :-(. I have first modified the array add-on to speed up element access, but it's not the bottleneck. After doing some profiling, it appears that most of the time is spent in the code that does the native function call, not the function itself. So I am wondering if there would be a way to register a specific data type in the engine that you would access directly in memory, without having to go thru a function call. Something like a buffer that could be shared between the C++ and the script, but with an operator [] built-in (directly in the engine) that returns the appropriate location in memory without having to go thru a function call. It would have to be smart enough to return the right type and size too (I think it it were limited to simple types such as int, float, double, etc. it would be enough). It could be pretty close to javascript's ArrayBuffer I guess, but with data type safety). I know it's not the main purpose of the engine (and it would actually break the data access safety), but it could be a great addon for data intensive apps. What do you think?

gjl

Author

468

January 16, 2014 04:44 PM

Ok, thanks, I will check this out and see what it could look like.

gjl

Author

468

January 20, 2014 11:20 AM

After some more testing, it appears that using the JIT with appropriate settings just makes performance so good that this is not required anymore! (JIT compiled code is just incredibly faster).

The first time I tried the JIT, I forgot to add the asEP_INCLUDE_JIT_INSTRUCTIONS option, hence the poor performance, By the way, why would this option not be automatically added to the engine when a JIT Compiler is registered?

theoutfield

291

January 20, 2014 07:48 PM

Are you using the JIT compiler from here

theoutfield

291

January 20, 2014 07:51 PM

The forum must not like direct links. Are you using the JIT compiler from here . If so could you post some results or a comparison? I haven't tried the JIT compiler. Angelscript has been fast enough for anything I've tried to do.

ThyReaper

488

January 20, 2014 08:30 PM

The forum must not like direct links. Are you using the JIT compiler from here . If so could you post some results or a comparison? I haven't tried the JIT compiler. Angelscript has been fast enough for anything I've tried to do.

Here are a few benchmarks I test against while developing the JIT:

Math:

No JIT: 1.55231ms

JIT: 0.570772ms

Script Call:

No JIT: 8.14899ms

JIT: 3.93928ms

System Call:

No JIT: 6.20815ms

JIT: 2.48501ms

Strings:

No JIT: 0.346983ms

JIT: 0.089297ms

Classes:

No JIT: 1.69336ms

JIT: 0.990286ms

System Classes:

No JIT: 6.21726ms

JIT: 1.6591ms

Switches:

No JIT: 2.57504ms

JIT: 0.261695ms

At least for these benchmarks, it's typically 2-4x faster. Specific use cases can go up to 10x faster (like the switch test).

theoutfield

291

January 21, 2014 02:33 AM

ThyReaper,

Those are some pretty good results. I am going to try this out when a I get a chance. Are there any things to watch out for, or is it pretty much plug and play? From the brief docs on Github it seems like its just a matter of registering the JIT compiler with the script engine and then business as usual. Great job, and thanks for the contribution!

Tony

WitchLord

4,860

January 21, 2014 03:19 PM

After some more testing, it appears that using the JIT with appropriate settings just makes performance so good that this is not required anymore! (JIT compiled code is just incredibly faster).

The first time I tried the JIT, I forgot to add the asEP_INCLUDE_JIT_INSTRUCTIONS option, hence the poor performance, By the way, why would this option not be automatically added to the engine when a JIT Compiler is registered?

I'll consider adding some check for this, though probably not to automatically turn on asEP_INCLUDE_JIT_INSTRUCTIONS. That wouldn't work with pre-compiled bytecode anyway.

AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

gjl

Author

468

January 21, 2014 07:30 PM

I'll consider adding some check for this, though probably not to automatically turn on asEP_INCLUDE_JIT_INSTRUCTIONS. That wouldn't work with pre-compiled bytecode anyway.

That's right, I had not thought about this!

gjl

Author

468

January 21, 2014 07:32 PM

And yes, that's the JIT I am using, I don't think there is any other anyway... I have just found a small memory leak, but otherwise it is really worth it! Any chance this would become integrated with angelscript directly in the future?

WitchLord

4,860

January 21, 2014 08:08 PM

And yes, that's the JIT I am using, I don't think there is any other anyway... I have just found a small memory leak, but otherwise it is really worth it! Any chance this would become integrated with angelscript directly in the future?

No. I have no plans to make this or any other JIT compiler part of the AngelScript SDK. BlindMind's JIT compiler is a completely separate project and is best maintained that way.

I believe BlindMind has made a good job of making the integration of the JIT compiler as smooth as possible anyway.

AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

array performance / direct memory access?

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