Re: Performance problem

[Andre Bleau <bleau at igb dot umontreal dot ca>]

If I am interpreting the output below correctly, you are developing an 
OpenGL program under X11; that's the main reason it is so slow.

OpenGL under X11 renders everything in software, without any hardware 
acceleration, so it's rendering is orders of magnitude slower. It is true 
that Cygwin's I/O and memory management are somewhat slower than under 
Linux, but that's peanuts compared to the OpenGL penalty.

If you want a fast program, you will have to use Window's native OpenGL 
implementation, which renders through hardware accelerators. That's what 
the OpenGL package for Cygwin provides.

Unfortunately, to use Window's native OpenGL implementation, you will have 
to rewrite completely such parts of your program as window management and 
user interface.

Last point (before you ask): the OpenGL implementation under X11 cannot be 
easily modified to use hardware acceleration, and I doubt it can be 
modified at all to do so. To know why, please search the archives for this 
list.

Vladimir Baltchev <vbaltch at orthosoft dot ca> wrote:
> Hi there,
> We are about to port Unix - Irix and Linux applications to Windows using 
> Cygwin. However the Cygwin version is very slow compared to Linux, even I 
> compiled with the optimize option -O2. It is a Windows 2000, the program 
> is a segmentation editor using Qt, OpenGl and some image processing.
> What is the reason? Is it OpenGL on cygwin, or both?
> Here is the library dependency list:
> segeditorMax.exe
> C:\cygwin\usr\X11R6\bin\libGL.dll
> C:\cygwin\usr\X11R6\bin\libX11.dll
> C:\cygwin\bin\cygwin1.dll
> C:\winnt\System32\KERNEL32.dll
> C:\winnt\System32\NTDLL.DLL
> C:\cygwin\usr\X11R6\bin\libXext.dll
> C:\cygwin\usr\X11R6\bin\libGLU.dll
> c:\qt-cygwin\qt-3\bin\cygqt-mt-3.dll
> C:\cygwin\usr\X11R6\bin\libICE.dll
> C:\cygwin\usr\X11R6\bin\libSM.dll
> C:\cygwin\usr\X11R6\bin\libXrender.dll
> C:\cygwin\bin\cygpng12.dll
> C:\cygwin\bin\cygz.dll
> C:\winnt\System32\ADVAPI32.DLL
> C:\winnt\System32\RPCRT4.DLL
> c:\Vlad\build\Dev\lib\libOip.dll
> C:\winnt\System32\GDI32.dll
> C:\winnt\System32\USER32.DLL



André Bleau, Cygwin's OpenGL package maintainer.

email: bleau at igb dot umontreal dot ca
(Fight SPAM: encode your email-address)

Please address all questions and problem reports about Cygwin's OpenGL 
package to cygwin@cygwin.com . 


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