How to interpret Profile Results

[Rafael Spring]

It's an Intel HD 4400. Here's some more information from GpuCapsViewer:

- Windows 8.1 64-bit build 9600
- OpenGL info:
 - GL_VERSION: 4.3.0 - Build 10.18.14.4170 (# ext: 208)
 - GL_RENDERER: Intel(R) HD Graphics 4400
  GPU 1 - Intel(R) HD Graphics Family
- GPU: Haswell
- Device  ID: 8086- A16
- Subvendor: Unknown (1414-   5)
- Driver version: 10.18.14.4170 ig75icd64.dll
- Bios version: Intel Video BIOS
- GPU memory size: 1024MB
- GPU cores: 40
- GPU Texture units: 1
- TDP: 84 Watts


On Fri, Oct 30, 2015 at 10:00 PM, Nigel Stewart <nigels.com at gmail.com>
wrote:

> Rafael,
>
> What specific GPU is in the Surface Pro?  At a fine granularity timing
> tends to vary due to threading, contention and threading.
>
> - Nigel
> On Oct 31, 2015 2:16 AM, "Rafael Spring" <rafael at dotproduct3d.com> wrote:
>
>> Hello,
>>
>> we are currently doing some performance testing of our GPU code and have
>> found that apitrace (a tool we really appreciate!) contains a profiling
>> tool that works with OpenGL.
>>
>> However we are a bit unsure how to interpret the results. According to
>> the Profile Results a lot of GPU time seems to be spent in draw calls of a
>> few simple shaders that don't draw a lot of pixels, whereas the complex
>> shaders that draw lots of pixels seem to be fairly quick. Also some of the
>> GPU draw call times seem to vary by orders of magnitude for the same shader
>> and operation (i.e. one call takes ~20 us and the next draw call,
>> performing the exact same operation with the same shader but possibly to a
>> different part of the framebuffer, takes 10000 us).
>> We suspect the execution times aren't always true compute times but may
>> contain stall times. Another theory is that some of the draw call times are
>> actually just scheduling times and the real computation time ends up
>> counting towards another draw call timing, when a batch of operations gets
>> executed.
>>
>> Any insight into how to interpret the Profile Results and how to derive
>> optimization insight from it would be greatly appreciated.
>>
>> For testing we are currently using a MS Surface Pro 3 tablet running
>> Windows 8.1.
>>
>> Thanks,
>> Rafael
>>
>>
>> --
>> Rafael Spring
>> CTO, Co-Founder
>> DotProduct LLC / DotProduct GmbH
>> rafael at dotproduct3d.com
>> www.dotproduct3d.com
>> m: +49 1525 3822738
>> @DotProduct3D
>>
>> _______________________________________________
>> apitrace mailing list
>> apitrace at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/apitrace
>>
>>


-- 
Rafael Spring
CTO, Co-Founder
DotProduct LLC / DotProduct GmbH
rafael at dotproduct3d.com
www.dotproduct3d.com
m: +49 1525 3822738
@DotProduct3D
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