I think that pinned VRAM memory (memory that's reserved for kernel use only) is subtracted from the total VRAM size. amdgpu DRM 3.9.0 has a new query that returns both the total physical and total usable VRAM, but Mesa doesn't use it. Marek On Sat, Dec 10, 2016 at 11:31 PM, Kai Wasserbäch <kai at dev.carbon-project.org> wrote: > Alex Deucher wrote on 10.12.2016 23:03: >> On Sat, Dec 10, 2016 at 4:52 PM, Kai Wasserbäch >> <kai at dev.carbon-project.org> wrote: >>> [Please CC me on all replies, I'm not subscribed to this list.] >>> >>> Dear Alex, >>> Alex Deucher wrote on 10.12.2016 22:40: >>>> On Fri, Dec 9, 2016 at 3:27 PM, Kai Wasserbäch >>>> <kai at dev.carbon-project.org> wrote: >>>>> [Please CC me on all replies, I'm not subscribed to this list.] >>>>> >>>>> Hey, >>>>> I've been noticing that GLX_MESA_query_renderer reports less video memory when I >>>>> use amdgpu for my Hawaii PRO GPU, than when I use radeon. Since I'm pretty happy >>>>> with amdgpu (as I do not use HDMI audio) and it's the code, that gets active >>>>> improvements, I'd like to stay with it, but having 40 MB of video memory >>>>> "vanish" is not nice. >>>>> With radeon GLX_MESA_query_renderer reports 4096 MB RAM (as expected, the R9 290 >>>>> was sold/advertised with that), while I'm seeing 4056 MB with amdgpu (last >>>>> tested kernel: 4.8.13). >>>>> >>>>> As I'm not sure, whether this is a bug or rather some always reserved memory >>>>> area, which gets subtracted before reporting the available memory, I didn't file >>>>> a bug report and rather am writing this e-mail. If it's a bug I'm happy to file >>>>> the report against amdgpu. >>>> >>>> IIRC, the driver interfaces used to get the information exposed via >>>> that extension are slightly different. radeon exposes the total >>>> amount of vram while amdgpu reports the total amount of free vram. >>>> The actual amount of free vram is probably pretty close. >>> >>> thanks for the explanation! >>> >>> But I'd like to point out that some of the automatic configuration tools shipped >>> with games (and probably other programs) are deciding upon the reported values >>> to which quality level they should default. Maybe reporting the theoretical VRAM >>> might be better (you could always report the actual values through sysfs or some >>> other channel)? >> >> I think all of the relevant info is available already, we'd just need >> to update mesa to make both drivers report something consistent. The >> extension isn't clear on whether it should be free memory or total >> memory. The extension says: >> >> GLX_RENDERER_VIDEO_MEMORY_MESA 1 Number of megabytes of video >> memory available to the renderer > > I agree, that the language of the spec isn't explicit in what should be reported. > >> That sort of implies free memory, but I guess most apps probably care >> more about the overall memory size. > > From what I've seen, that seems the case (no matter through which extension this > value is queried). It seems like this is how it's handled on Windows: if you > have 4 GB of VRAM, we default to high level textures, if you have 8 GB, we > default to ultra, etc. > > Cheers, > Kai > > > _______________________________________________ > amd-gfx mailing list > amd-gfx at lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx >
