Messages in this thread | | | Subject | MTRR vesafb and wrong X performance | From | Pawel Fengler <> | Date | Thu, 25 Nov 2004 00:15:39 +0100 |
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Dear Sirs,
Recenly, I test five big distributions with almost all kernels from 2.4.21 to 2.6.9 on several slow computers with many different (not quite new) graphics cards (most of them - nvidia: Riva TNT, GeForce, GeForce2 and S3Savage). I observe very wrong Xserver performance on each of kernel 2.6.x and good performance on every 2.4.x kernel when computer boot with vesafb For example, when I try mplayer or xine - CPU utilization by X process is 30 times larger on 2.6.x kernel then 2.4.x
==> top_2.4.27-0.pre2.1mdk <== top - 14:27:50 up 7 min, 1 user, load average: 0.67, 0.25, 0.11 Tasks: 45 total, 3 running, 42 sleeping, 0 stopped, 0 zombie Cpu(s): 27.4% user, 1.5% system, 0.0% nice, 71.1% idle Mem: 190780k total, 106124k used, 84656k free, 5864k buffers Swap: 626452k total, 0k used, 626452k free, 63480k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1549 pf 25 0 16684 16m 12m R 26.4 8.7 0:16.00 mplayer 1398 root 25 0 42620 9596 3028 S 0.3 5.0 0:03.33 X 1561 pf 25 0 13032 12m 12m R 0.3 6.8 0:00.18 mplayer
==> top_2.6.8.1-12mdk <== top - 20:41:33 up 13 min, 1 user, load average: 0.93, 0.35, 0.21 Tasks: 48 total, 2 running, 46 sleeping, 0 stopped, 0 zombie Cpu(s): 61.7% us, 3.5% sy, 0.0% ni, 34.5% id, 0.0% wa, 0.1% hi, 0.0% si Mem: 191608k total, 113028k used, 78580k free, 6064k buffers Swap: 626452k total, 0k used, 626452k free, 66712k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 3841 pf 15 0 34320 16m 27m S 36.2 8.7 0:21.94 mplayer 3655 root 16 0 44448 9708 36m R 26.0 5.1 0:17.99 X 3715 pf 15 0 3224 1768 2764 S 0.8 0.9 0:00.82 rxvt.bin 3842 pf 15 0 29932 12m 27m S 0.5 6.8 0:00.28 mplayer
Every time when I use 2.6.x kernel I get warnigs (in xorg.log) similar this: (WW) NV(0): Failed to set up write-combining range (0xe3000000,0x1000000)
When I use boot option "video=vesafb:nomtrr" with any 2.6.x kernel, Xserver performance is nearly as good as under 2.4.x kernel and warning (in xorg.log) does not appear.
It seems to be a problem with mtrr and vesafb described several times, for example Jan 18, 2004 in thread "Overlapping MTRRs in 2.6.1" but it was a long time ago.
My questions are simple: 1. The problem is because of a kernel bug or because of kernel feature? 2. Is this the same problem all the time not resolved yet or I found several different kernel bugs (with the same symptoms)? I did not test 2.6.0, 2.6.2 and 2.6.5 kernel yet:-)
Inspite of this problem is not as important as for example kernel panic I am sure because of it many of trivial users think linux is slowly :-)
Pawel Fengler
P.S. Sorry for my English. It is not as perfect as I wish it to be.
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