On 6 Sep, this message from Mark Vojkovich echoed through cyberspace: > On Thu, 5 Sep 2002, Michel Lanners wrote: > >> On 4 Sep, this message from Mark Vojkovich echoed through cyberspace: >> >> Is there any way to grab a screenshot really fast. I mean like a 1280x1024 >> >> 32bbp screenshot in a couple of milliseconds? I am using XShmGetImage() >> >> right now, but a screenshot of the size mentioned above takes about 110 to >> >> 120 milliseconds. Doing the math this gives me a bandwidth of about 40 to >> >> 45 MB/s. Surely there must be a faster way of doing it. >> >> >> >> The system i am sitting on is a Linux box, XFree 4.2.0, nVidia graphics >> >> (GF2) with the nVidia binary driver. >> >> >> > No, there's not a way to copy quickly from the framebuffer. >> > Reads across AGP are limited to PCI bandwidth. I am seeing over >> > 100 MB/sec in general though (closer to 150 MB/sec on fast P4s). >> >> Would there be a way to use the graphic chip's blitter to copy the >> framebuffer contents over AGP to main memory? >> >> Cheers > > The nvidia driver does use the graphics engine to do the copy. > Running that benchmark on other drivers you'll see they get about > a tenth the performance of the nvidia driver.
Out of curiosity, are you using any PCI 'high-performance' commands like MemoryReadMultiple or MemoryWriteInvalidate to transfer over the bus? Cheers Michel ------------------------------------------------------------------------- Michel Lanners | " Read Philosophy. Study Art. 23, Rue Paul Henkes | Ask Questions. Make Mistakes. L-1710 Luxembourg | email [EMAIL PROTECTED] | http://www.cpu.lu/~mlan | Learn Always. " _______________________________________________ Xpert mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xpert
