I think this is the same issue that another user reported and which has been fixed in the VirtualGL CVS head. When an application has set the render mode to GL_SELECT and calls glFlush() while doing front buffer rendering, this causes very slow glReadPixels() performance on nVidia hardware. The fix was to detect whether GL_SELECT is enabled whenever the VirtualGL readback function is called and, if so, to temporarily disable it before performing the readback.
Unfortunately, SourceForge has still not re-enabled their CVS server in the wake of last week's security attack, so I cannot access the VirtualGL code right now. If I could, I would spin a pre-release build for you to try out. On 1/31/11 8:52 AM, David Björkevik wrote: > Dear List > > I have an installation of VirtualGL using Cendio Thinlinc on an 8 core > machine with Nvidia Quadro graphics. > > Performance is excellent except when our application uses "picking" to > detect what part of the OpenGL scene the user is clicking at. > > After picking, the program hangs for about a second with no regard to > the size of the model itself. When halting with GDB, the backtrace shows > the > > I tried the VGL_PROFILE option. Standard values for Readback are in the > 300-600 Mpixels/sec range. However, when picking, this drops to <1 > Mpixels/sec. > > Any pointers or ideas? > > Thanks! > > /David > > > > > ------------------------------------------------------------------------------ > Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! > Finally, a world-class log management solution at an even better price-free! > Download using promo code Free_Logger_4_Dev2Dev. Offer expires > February 28th, so secure your free ArcSight Logger TODAY! > http://p.sf.net/sfu/arcsight-sfd2d > > > > _______________________________________________ > VirtualGL-Users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/virtualgl-users ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ VirtualGL-Users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/virtualgl-users
