Re: Triangle performance problem

Subject: Re: Triangle performance problem

From: Paul Sargent <email@hidden>

Date: Mon, 18 May 2009 11:33:50 +0100

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On 18 May 2009, at 10:59, Space Ship Traveller wrote:

Here are some details from the OpenGL Profiler I managed to figure out some things (I just included the top 5 as all the other ones are not that interesting):

GL Function # of Calls Total Time (µsec) Avg Time (µsec) % GL Time % App Time
CGLFlushDrawable 1,265 4087917 3231.56 82.08 6.86
glDrawArrays 2,106 260195 123.55 5.22 0.44
glBegin 14,525 140308 9.66 2.82 0.24
glClear 1,265 139147 110.00 2.79 0.23
glDrawElements 3,398 121990 35.90 2.45 0.20

So, from this I can see that glDrawArrays is taking up 5% of OpenGL time.

... and 0.44% of the App time. If you got this time to zero you'd be speeding up your application by 0.44%.

This is not what is limiting your performance, it's the 93% of CPU time spent outside of OpenGL (100% - 7% App Time)

What is OpenGL time? Is that the time my process spends in the OpenGL library?

Yep, exactly... and app time is the time spent in your whole application. At the moment only 7% of your time is spent in OpenGL.

Is there any documentation about how to make this faster? Is this considered slow?

I'd say you need to be looking outside of your drawing code. Try firing up Shark and see what that tells you.

Paul

BTW: working those numbers backwards. I'll assume this was 1,265 frames (i.e. one clear, and one flush per frame)

Thats

1->2 glDrawArrays per frame

2 -> 3 glDrawElements per frame

11->12 glBegins per frame

A. Your not giving OpenGL much work to do, so extrapolating performance is not really valid.

B. Your code has glBegins in it, so it's not on a fast path.

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Follow-Ups:

Re: Triangle performance problem
- From: Space Ship Traveller <email@hidden>
Re: Triangle performance problem
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References:

>Triangle performance problem (From: Space Ship Traveller <email@hidden>)

>Re: Triangle performance problem (From: Steven Canfield <email@hidden>)

>Re: Triangle performance problem (From: Space Ship Traveller <email@hidden>)