Jan Knutar wrote: > On Tuesday 28 October 2008, RC wrote: >> On Mon, 27 Oct 2008 23:30:02 +0200 >> >> Jan Knutar <jknutar at nic.fi> wrote: >>> This makes no difference, XV transfers the video as 12bpp (YV12) >>> regardless of x11 colour depth. >> Point taken. I suppose with such a low BPP that would preclude >> overwhelming the PCI bus at that resolution as well. > > > Well it's not overwhelmed if it's keeping up ;) > > I've seen similar differences between PCI and PCIe myself. Maybe the Xv > driver doesn't DMA? At least lspci shows busmaster capability for the PCI graphics, and with pictures that are not so big the speed is reasonable. I finished up plugging in my old PCI-e card in the remaining 4x-slot (which is able to retain a 16x-card since it is open on the back side - had I known this earlier, I wouldn't have bothered to getting a decent PCI graphics card). Point is, more than ~60MB/s on PCI are not that easy to achieve, PCIe per lane offers 250MB/s. A 1280x720 video at 24bpp, 24fps has around 80MB/s, which are quite close to the theoretical maximum of PCI, but less than a third of the theoretical maximum of a PCIe-1x (let alone 16x). Complicating the fact is the nvidia closed source driver, where no-one can be sure what happens internally... I'd be happy to switch to nv or maybe nouveau, if it correctly supports XV and multi-head (and perferrably twin-view on one card). 3d is of no interest to me whatsoever. -- cheers, Alexe
