From: Knut P. <Knu...@t-...> - 2005-07-29 14:52:57
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Hi everybody! >>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 |