https://bugs.freedesktop.org/show_bug.cgi?id=97260
--- Comment #20 from Kai kai@dev.carbon-project.org --- Created attachment 125820 --> https://bugs.freedesktop.org/attachment.cgi?id=125820&action=edit dmesg output with additional debug info from attachment 125808
(In reply to Alex Deucher from comment #16)
Does just reverting this chunk fix the issue?
@@ -1630,6 +1631,9 @@ int radeon_modeset_init(struct radeon_device *rdev)
rdev->ddev->mode_config.funcs = &radeon_mode_funcs;
if (radeon_use_pflipirq == 2 && rdev->family >= CHIP_R600)rdev->ddev->mode_config.async_page_flip = true;if (ASIC_IS_DCE5(rdev)) { rdev->ddev->mode_config.max_width = 16384; rdev->ddev->mode_config.max_height = 16384;
Yes, just removing the default enable here has the same effect as reverting the entire patch.
(In reply to Michel Dänzer from comment #18)
Created attachment 125808 radeon: Add some page flip debugging output
Well, that's a surprising result of the bisection.
I can imagine two possible causes, or possibly some combination thereof:
- The processing of asynchronous flips or the corresponding completion
interrupts is delayed for some reason
- Using flips instead of blits for buffer swaps lowers the load on the GPU 3D engine, so the SMU doesn't switch to higher clocks
The attached debugging patch should give us more information about the former. With it applied, run the following while an affected application is running in fullscreen:
sudo sh -c 'echo 2 >/sys/module/drm/parameters/debug'; sleep 1; sudo sh -c 'echo 0 >/sys/module/drm/parameters/debug'
Then attach the resulting dmesg output.
Here you go. That was generated by running XCOM 2.
BTW, does the problem still happen with Alex's current drm-next-4.9-wip branch?
Haven't tested that yet. Maybe somebody else can do that. ;-)
(In reply to Michel Dänzer from comment #19)
BTW, there are some potential workarounds:
Disable DRI3 for affected games with the environment variable LIBGL_DRI3_DISABLE=1
Enable sync-to-vblank in affected applications, or force it with
vblank_mode=3
Well, this is going to be odd: I had VSync enabled in XCOM, since without that option I got poorer performance in the past than with it. Now, after your note here I actually *disabled* the VSync option in the game. 4.6.4 (or 4.7.0 without the offending commit/the enable removed) shows no longer a performance difference and I'm getting ~30 FPS in XCOM 2. BUT with your ASYNC patch (vanilla 4.7.0) and VSync turned of in the game gives me ALSO ~30 FPS! I'd still say this is a regression as there is no difference without your patch, but maybe this information can help you in narrowing down the cause?
I hope I haven't missed any open question. Let me know if you need anything else.