On Tue, 2002-10-22 at 21:51, Keith Packard wrote: > How expensive is it on a uniprocessor system? Copying data prior to DMA > is not free, especially if the buffers span a significant fraction of > the cache size.
Its actually very hard to measure, because the impact is felt down the line not immediately. Not only do you pay the tlb flush cost you then pay repeated reload costs to get TLB's back. x86 isnt very good at "drop one tlb" I can believe there are objects in 3D rendering big enough to be worth mapping but I'd be guessing to name a size. Linus as a chip hacker might actually have more detailed numbers. Is it neccessary to copy all the data then DMA it or can you pipeline it so that the DMA is writing out some of the cache while you copy data in and verify it ? ------------------------------------------------------- This sf.net emial is sponsored by: Influence the future of Java(TM) technology. Join the Java Community Process(SM) (JCP(SM)) program now. http://ad.doubleclick.net/clk;4699841;7576301;v?http://www.sun.com/javavote _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
