[Bug 50616] New: glClear occasionally taking >60ms

[Bug 50616] New: glClear occasionally taking >60ms

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=50616

             Bug #: 50616
           Summary: glClear occasionally taking >60ms
    Classification: Unclassified
           Product: Mesa
           Version: 8.0
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: minor
          Priority: medium
         Component: Drivers/Gallium/r600
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: curaga@operamail.com


I have a test app that draws 65k point sprites, apitrace:
http://kiwi6.com/file/0c0512r1no (980kb).

Apitrace says that on average glClear takes 28ms, and many clear calls take
over 60ms. Surely it shouldn't take that long?

If it were because of tearing prevention, it should take at most 16ms (1/60Hz).


--

vblank_mode=0 had no change, oprofile says Mesa takes less than 2% cpu.
Latencytop shows radeon_fence_wait taking between 3 and 5ms during rendering.

--

Mesa 8.0.3
Linux 3.2.17
HD4350 / r600g

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[Bug 50616] glClear occasionally taking >60ms

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https://bugs.freedesktop.org/show_bug.cgi?id=50616

--- Comment #1 from Lauri Kasanen <curaga@operamail.com> 2012-06-02 06:32:41 PDT ---
http://kiwi6.com/file/95a4z148f2 (550kb)

The timing output from apitrace.

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[Bug 50616] glClear occasionally taking >60ms

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https://bugs.freedesktop.org/show_bug.cgi?id=50616

--- Comment #2 from Alex Deucher <agd5f@yahoo.com> 2012-06-03 08:08:04 PDT ---
Does setting:
Option "SwapbuffersWait" "false"
in the device section of your xorg.conf help?

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[Bug 50616] glClear occasionally taking >60ms

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https://bugs.freedesktop.org/show_bug.cgi?id=50616

--- Comment #3 from Lauri Kasanen <curaga@operamail.com> 2012-06-03 08:22:27 PDT ---
No, it does not.

It improved the average a tiny bit, but the long ones were still there.

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[Bug 50616] glClear occasionally taking >60ms

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=50616

--- Comment #4 from Michel Dänzer <michel@daenzer.net> 2012-06-05 03:46:52 PDT ---
(In reply to comment #3)
> It improved the average a tiny bit, but the long ones were still there.

Did you try it with vblank_mode=0 as well?


Calling glFinish() instead of glFlush() before glXSwapBuffers() might give a
better idea of where the time is actually spent.


P.S. Please attach files here directly instead of referencing external sites.

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[Bug 50616] glClear occasionally taking >60ms

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=50616

--- Comment #5 from Lauri Kasanen <curaga@operamail.com> 2012-06-05 11:42:35 PDT ---
OK, with swapbufferswait off, vblank_mode=0, and added glFinish, most of the
time is indeed spent in glFinish, up to 60ms.

glClear takes on average 110 us, with the highest being 2.6ms. Still high, but
not alarmingly so.

I suppose this means the card is just that slow?

PS:
On the files, last time I tried to attach apitrace output here I hit a size
limit...

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[Bug 50616] glClear occasionally taking >60ms

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=50616

--- Comment #6 from Michel Dänzer <michel@daenzer.net> 2012-06-06 02:13:30 PDT ---
(In reply to comment #5)
> I suppose this means the card is just that slow?

It means the time is spent for the actual rendering, not just for the clears.
Maybe you can narrow it down further, e.g. by sprinkling glFinish() calls
across more places.

You might get better performance out of the card with a current 3.5-rc kernel
thanks to better tiling setup, but it is a lower end card, so I wouldn't expect
any miracles. :)

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[Bug 50616] glClear occasionally taking >60ms

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=50616

Lauri Kasanen <curaga@operamail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |NOTABUG

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