On Tue, Feb 25, 2014 at 11:11 AM, Christian König <deathsimple@xxxxxxxxxxx> wrote: > Am 24.02.2014 20:39, schrieb Marek Olšák: > >> On Mon, Feb 24, 2014 at 5:40 PM, Christian König >> <deathsimple@xxxxxxxxxxx> wrote: >>> >>> Am 24.02.2014 16:20, schrieb Marek Olšák: >>>> >>>> 1) Add virtual memory support for VRAM. Our GPUs support virtual memory, >>>> which not only solves fragmentation issues, but it also allows each >>>> buffer >>>> to be partially in VRAM and partially in GTT, which becomes more >>>> important >>>> with large buffers like 100 MB. Moving whole buffers back and forth >>>> between >>>> VRAM and GTT is inefficient if you can do it at page granularity. Also, >>>> due >>>> to fragmentation, we can never really use all of VRAM, but only about >>>> 90-95%. >>> >>> >>> Yeah, I'm also thinking about this for quite some time now. The basic >>> problem is that while our GPUs support VM they don't support faulting >>> pages >>> in and continuing (at least nobody got that working reliable so far). >>> E.g. >>> when you hit a page fault you can't relocate the page and then continue. >>> >>> Support for partially resident textures on newer hardware currently works >>> by >>> splitting the buffer up into smaller buffers in userspace and then >>> actively >>> checking in the shader if we hit a buffer that's not currently in memory, >>> but that's not really applicable in the general use case (to much shader >>> overhead). >> >> I was thinking of splitting buffers into smaller chunks and treating >> them like independent TTM buffers, i.e. one radeon_bo would contain an >> array of TTM buffers which would be validated independently of each >> other. The chunks would only be mapped together to make them look like >> one buffer. This would be hidden from userspace and there would only >> be one GEM handle for the whole buffer, so that DRI2 sharing works. > > > My thoughts where more to to this on the userspace side, but doing it in the > kernel indeed avoids a bunch of problems with sharing the buffer. > > Sounds like a plan to me. The only thing I can currently see missing is > handling of scanout buffers. Do we have a flag for this while creating the > buffer? We have a flag in Mesa, but not in the kernel. We can put it in drm_radeon_gem_create::flags though. Marek _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
