[Bf-committers] gDEBugger GDC Video: Advanced OpenGL, OpenGL ES and OpenCL debugging and profiling using gDEBugger

[Yves Poissant]

Not cheap but very usefull indeed. It is no magic however. You need to 
already have experience with OpenGL, The debugger can flag missused or 
overused API calls as well as deprecated OpenGL APIs. Several statistics are 
reported too. The most usefull output is the OpenGL calls dump per frame. 
With instrumentation drivers on the graphics card, it is informative to 
watch different counters while the appliaction is running.

That said, this debugger is not a replacement for true application profiler.

The trial version is quite crippled but it can give you a good idea of what 
it can do. You can obtain another 7 days trial extension from the company. 
For proper evaluation, you will need constant use for several days in order 
to fully understand all the tools it includes. No need for special build 
versions for your application. The debugger intercept all calls to the 
OpenGL driver.

One interresting discovery I made while using this debugger is that all the 
OpenGL optimizing tricks that were presented at Siggraph in previous years 
do not apply with the new graphics cards. These tricks are oftentime 
detrimental to optimizing OpenGL on new GPUs. So take care with old 
optimizing advises you will find on the web.

One issue I found with the locked version is that if you want to profile OGL 
on different graphics cards, you need to change the graphics card and its 
drivers on that locked-on computer. Not an easy proposition. That said, you 
can buy 3 locked licence for the price of a floating one.

Also, for the price of that tool, it is not a tool that I constantly use. I 
use it for short but intensive profiling periods and then don't use it for 
loooong period of times. So if I had to pay for the tool myself (my employer 
did), I would think more than twice. Especially given that now that I've 
used this profiler, I have a pretty good idea of how I would profile an 
OpenGL application without the tool and just by using the instrumentation 
drivers for OpenGL and the profiling API that are provided for free by 
Nvidia.

I'm not aware of any truely equivalent free software anywhere. There are 
some remnents of such free tools from the times of SGI OpenGL but they are 
essentialy of no use today.

Yves

----- Original Message ----- 
From: "Dalai Felinto" <dfelinto at gmail.com>
To: "bf-blender developers" <bf-committers at blender.org>
Sent: Wednesday, March 24, 2010 12:38 PM
Subject: Re: [Bf-committers] gDEBugger GDC Video: Advanced OpenGL,OpenGL ES 
and OpenCL debugging and profiling using gDEBugger


> Complementing:
> gdebugger has a trial for 7 days and is cross-plataform. The price is not
> cheap ($790 Node Locked and $2450 Floating - * Linux has only floating) 
> but
> I believe they are other tools out there that can do similar and are open
> software. Not sure about interface, performance, ...
>
> Cheers,
> Dalai
>
> 2010/3/24 Dalai Felinto <dfelinto at gmail.com>
>
>> Hi folks,
>> I watched the following video and I'm quite impressed:
>> http://nvidia.fullviewmedia.com/gdc2010/13-avi-shapira.html
>>
>> In BGE current profiling the whole Rasterizer is keep as an unique entry.
>> With this debugger you can actually see where is the actual bottleneck
>> (Fragment, Vertex, ...). The same can be applied for Blender I believe.
>>
>> When I find time I'll try to run it on simple BGE demos. I have a feeling
>> that this can help to fix some bugs we have (e.g. alpha flickering). Also
>> from a user perspective, that sounds as a handy tool to help
>> game optimization (assuming we can tackle the main BGE GL problems that 
>> may
>> be present).
>>
>> Maybe an interesting GSOC for someone? (to implement openGL Rasterizer
>> profile and fix/optimize BGE openGL errors)?
>>
>> Cheers,
>> Dalai
>>
>> http://blenderecia.orgfree.com
>>
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