On 27/08/16 05:07 AM, Mario Kleiner wrote: > On 08/18/2016 04:32 AM, Michel Dänzer wrote: >> On 18/08/16 08:51 AM, Mario Kleiner wrote: >>> >>> and the offload gpu imports those and renders into them. That saves >>> one extra copy, so should be somewhat more efficient. >> >> Using two shared buffers actually isn't as efficient as possible wrt >> inter-GPU bandwidth. > > Out of interest, why? You'd have only one detiling copy VRAM -> RAM? Yeah, that's basically it. With a single shared buffer, only the parts which have changed since last time need to be copied between the GPUs; the slave GPU can copy the other changed parts from its other local scanout pixmap (with TearFree enabled; note that this isn't quite implemented yet in our drivers for slave output, but I'm planning to do it soon). With two shared pixmaps, some changed parts have to be copied between GPUs several times. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
