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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [bisected] R9 290 low performance in Linux 4.7"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97260#c20">Comment # 20</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [bisected] R9 290 low performance in Linux 4.7"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97260">bug 97260</a>
from <span class="vcard"><a class="email" href="mailto:kai@dev.carbon-project.org" title="Kai <kai@dev.carbon-project.org>"> <span class="fn">Kai</span></a>
</span></b>
<pre>Created <span class=""><a href="attachment.cgi?id=125820" name="attach_125820" title="dmesg output with additional debug info from attachment 125808">attachment 125820</a> <a href="attachment.cgi?id=125820&action=edit" title="dmesg output with additional debug info from attachment 125808">[details]</a></span>
dmesg output with additional debug info from <span class=""><a href="attachment.cgi?id=125808" name="attach_125808" title="radeon: Add some page flip debugging output">attachment 125808</a> <a href="attachment.cgi?id=125808&action=edit" title="radeon: Add some page flip debugging output">[details]</a></span> <a href='page.cgi?id=splinter.html&bug=97260&attachment=125808'>[review]</a>
(In reply to Alex Deucher from <a href="show_bug.cgi?id=97260#c16">comment #16</a>)
<span class="quote">> 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;</span >
Yes, just removing the default enable here has the same effect as reverting the
entire patch.
(In reply to Michel Dänzer from <a href="show_bug.cgi?id=97260#c18">comment #18</a>)
<span class="quote">> Created <span class=""><a href="attachment.cgi?id=125808" name="attach_125808" title="radeon: Add some page flip debugging output">attachment 125808</a> <a href="attachment.cgi?id=125808&action=edit" title="radeon: Add some page flip debugging output">[details]</a></span> <a href='page.cgi?id=splinter.html&bug=97260&attachment=125808'>[review]</a>
> 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.</span >
Here you go. That was generated by running XCOM 2.
<span class="quote">> BTW, does the problem still happen with Alex's current drm-next-4.9-wip
> branch?</span >
Haven't tested that yet. Maybe somebody else can do that. ;-)
(In reply to Michel Dänzer from <a href="show_bug.cgi?id=97260#c19">comment #19</a>)
<span class="quote">> 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</span >
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.</pre>
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