Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 47

Thread: Quad-Monitor AMD/NVIDIA Linux Gaming: What You Need To Know

  1. #21
    Join Date
    Aug 2012
    Location
    Pennsylvania, United States
    Posts
    1,858

    Default

    Quote Originally Posted by agd5f View Post
    AMD GPUs only have two PLLs which means we can only support two independent non-DP clocks. If you want to use more than two monitors, the additional monitors have to be DP. If you try again with 2 DVI/HDMI and 2 DP monitors it should work. Catalyst enforces this requirement. On radeon we allow PLL sharing where it's possible (e.g., multiple panels with the same clock) which is why it works there. That has it's own limitations however. E.g., if you try and change to a configuration that requires more than two PLLs, the modeset will fail.
    Alex does the PLL sharing affect the performance? Or is Radeon just not good at multi-monitor at this point? Or is the driver (not sure if its RadeonSI or R600g) for the 6950 just not as close to Catalyst for FPS? Just trying to figure out the numbers gap between Radeon and Catalyst on some of these benchmarks

  2. #22
    Join Date
    Dec 2007
    Posts
    2,315

    Default

    Quote Originally Posted by Ericg View Post
    Alex does the PLL sharing affect the performance? Or is Radeon just not good at multi-monitor at this point? Or is the driver (not sure if its RadeonSI or R600g) for the 6950 just not as close to Catalyst for FPS? Just trying to figure out the numbers gap between Radeon and Catalyst on some of these benchmarks
    PLLs don't affect gfx performance. Having a huge desktop does however. Not only are you rendering to a much larger surface, you have more contention in the memory controller for bandwidth (display controllers and the gfx hardware). You can save bandwidth by doing pageflips rather than blit for buffer swaps, but at the moment, the open source drivers don't support non-vsynced pageflipping due to limitations in the xserver. When you are rendering to huge buffers you also tend to run out of vram so buffers may end up ping-ponging between vram and system memory from frame to frame. Improving the buffer placement heuristics in the open source driver would probably help a lot in vram limited cases.

  3. #23
    Join Date
    Nov 2009
    Location
    Italy
    Posts
    905

    Default

    Quote Originally Posted by agd5f View Post
    You can save bandwidth by doing pageflips rather than blit for buffer swaps, but at the moment, the open source drivers don't support non-vsynced pageflipping due to limitations in the xserver.
    Which ones? Afaik Intel already does Async Display Flipping thanks to DRI3.
    ## VGA ##
    AMD: X1950XTX, HD3870, HD5870
    Intel: GMA45, HD3000 (Core i5 2500K)

  4. #24
    Join Date
    Aug 2012
    Location
    Pennsylvania, United States
    Posts
    1,858

    Default

    Quote Originally Posted by agd5f View Post
    PLLs don't affect gfx performance. Having a huge desktop does however. Not only are you rendering to a much larger surface, you have more contention in the memory controller for bandwidth (display controllers and the gfx hardware). You can save bandwidth by doing pageflips rather than blit for buffer swaps, but at the moment, the open source drivers don't support non-vsynced pageflipping due to limitations in the xserver. When you are rendering to huge buffers you also tend to run out of vram so buffers may end up ping-ponging between vram and system memory from frame to frame. Improving the buffer placement heuristics in the open source driver would probably help a lot in vram limited cases.
    2 Questions outta that...

    1) Is a the 'non vsynced pageflipping' issue present on Wayland?

    2) Will 'ping-ponging' be an issue on HSA systems? AMD CPU with an AMD dedicated card. I haven't checked out the HSA spec so I don't know if you can request to be put on graphics RAM vs system RAM or if you really are just saying "I need a buffer with xyz size" and get given back a pointer and youre blind to whether or not its on DDR3 ( / 4) or GDDR5. Just a thought that came up, figured I'd throw it in haha

  5. #25
    Join Date
    May 2013
    Posts
    38

    Default

    Quote Originally Posted by agd5f View Post
    AMD GPUs only have two PLLs which means we can only support two independent non-DP clocks. If you want to use more than two monitors, the additional monitors have to be DP. If you try again with 2 DVI/HDMI and 2 DP monitors it should work. Catalyst enforces this requirement. On radeon we allow PLL sharing where it's possible (e.g., multiple panels with the same clock) which is why it works there. That has it's own limitations however. E.g., if you try and change to a configuration that requires more than two PLLs, the modeset will fail.
    Here's some more reading backing what agd5f saying.

    http://www.anandtech.com/show/7400/t...eat-asus-xfx/3

    One side question: Does open source radeon driver support 4K display now?

  6. #26
    Join Date
    Dec 2007
    Posts
    2,315

    Default

    Quote Originally Posted by darkbasic View Post
    Which ones? Afaik Intel already does Async Display Flipping thanks to DRI3.
    That requires dri3 and present support. The problem in pre-dri3 land is that the xserver doesn't make the swap interval available to the driver so they can decide whether they want to flip or swap. There have been several attempts to fix it, but nothing has ever made it upstream.

  7. #27
    Join Date
    Aug 2012
    Location
    Pennsylvania, United States
    Posts
    1,858

    Default

    Quote Originally Posted by agd5f View Post
    That requires dri3 and present support. The problem in pre-dri3 land is that the xserver doesn't make the swap interval available to the driver so they can decide whether they want to flip or swap. There have been several attempts to fix it, but nothing has ever made it upstream.
    I'm assuming though that DRI3 and Present support is on the roadmap for Radeon?

  8. #28
    Join Date
    Dec 2007
    Posts
    2,315

    Default

    Quote Originally Posted by Ericg View Post
    I'm assuming though that DRI3 and Present support is on the roadmap for Radeon?
    Yes it is.

  9. #29
    Join Date
    Aug 2012
    Location
    Pennsylvania, United States
    Posts
    1,858

    Default

    Quote Originally Posted by agd5f View Post
    Yes it is.
    Juuuust checking, thanks for answering questions Alex

  10. #30
    Join Date
    Dec 2007
    Posts
    2,315

    Default

    Quote Originally Posted by lovenemesis View Post
    Here's some more reading backing what agd5f saying.

    http://www.anandtech.com/show/7400/t...eat-asus-xfx/3

    One side question: Does open source radeon driver support 4K display now?
    The driver side should be fine assuming you have a new enough kernel to properly parse the 4k modes from the monitor.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •