Re: Fw: framebuffer blitting performance loss 2.6.12 -> 2.6.13-rc3

Hi everybody!

quoted

I haven't seen any significant performance penalty, between 2.6.12-rc5-mm1
and 2.6.13-rc3-mm1.

Based on your results, I would pinpoint the culprit to be in
video/console/bitblit.c.  However, the changes there are minor, and should not
alter the peformance.

So.. what happened here?  Is the problem still present in 2.6.13-rc4?

Yes, the problem still is present in 2.6.13-rc4.
================================================

There is only an insignificant difference of max +/- 2ms between
2.6.13-rc3 and 2.6.13-rc4 for all measurements.

Test 1:   reset;time cat scrolltest0
Test 2:   reset;time cat scrolltest80
Test 3:   reset;time cat scrolltest160

scrolltest0 is a file with 2000 empty lines.
scrolltest80 is a file with 2000 lines of 80 characters each.
scrolltest 160 is a file with 2000 lines of 160 characters each.

vesafb tests are made with the original vesafb of the respective kernel versions,
cyblafb tests all use the same source file, accelerations: fillrect, bitblit, copyarea
2.6.13-rc* are compiled for 1000Hz system timer as it is also used for 2.6.12.

chipset: trident cyberblade/i1
video mode: vesa 0x307 (1280x1024@75hz)
8x16 font

Nothing but the kernel changed between the tests,
the time values given are system time in seconds.


vga=0x307 | test 1   test 2   test 3  | test 1   test 2    test 3           |    video=vesafb:ypan      |       video=vesafb
-----------+---------------------------+---------------------------
2.6.12     | 3,753s   4,825s   5,936s  | 4,258s  65,645s  126,898s
2.6.13-rc4 | 3,937s   5,135s   6,302s  | 4,304s  71,515s  138,674s
          |  +4,9%   +6,42%   +6,17%  | +1,08%   +8,94%    +9,28%


vga=0x307 | test 1   test 2   test 3  | test 1   test 2    test 3           |    video=cyblafb          |   video=cyblafb:noypan
-----------+---------------------------+---------------------------
2.6.12     | 0,228s   0,549s   0,870s  | 7,692s   8,015s    8,335s
2.6.13-rc4 | 0,235s   0,654s   1,072s  | 7,699s   8,120s    8,549s
          | +3,07%  +19,13%  +23,22%  | +0,09%   +1,31%    +2,57%


The numbers show very clearly that 2.6.13-rc* blitting is much slower than
the blitting of 2.6.12. For cyblafb the time spend for the actual blitting is
about 257ms for test3, so the actual performance loss for the pre-driver part
is above 30%

Now for a real world example:

     reset; time cat patch-2.6.13-rc4

cyblafb, kernel 2.6.12     : 173,013s
cyblafb, kernel 2.6.13-rc4 : 196,181s
  difference              :  23,168s ( +13,4% )

Could anyone take the time to measure performance of some other drivers?
Those using ypan scrolling and hardware accelerated bitblit should be
most affected.


cu,
Knut





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