> From: Keith Whitwell [mailto:[EMAIL PROTECTED]] > > Just look at /proc/pci or similar on a linux box. All the > pci cards have > memory ranges assigned to them - that's where your on-card > memory lives in the > physical address space. The pci bus hardware diverts memory > accesses in this > range to the appropriate card. But don't use it if you can > avoid it, as > Gareth mentioned, because it is as slow as a dog. > > Keith
If you do a small loop that stores a constant value into the grafics board's pci mapped memory window (which size must not be equal to the total amount of grafics memory) then you may get transfer rate values up to the maximum speed of the PCI bus protocoll, or much less if the grafics board does slow down due to design. If you instruct the grafics board to initiate an AGP transfer reading from main memory, then you could currently get AGP 4x Speed (4x = 4 times PCI speed) or the maximum memory bandwidht (some 1,6 to 3,2 GB/sec is common memory performance) whichever is smaller. If the grafics board does the requests slower, then its so by its design. Regards Alex. _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
