Am Freitag, 17. April 2009 schrieb Brice Goglin: > > $ uname -a > > Linux Zweiblum 2.6.26-2-686 #1 SMP Thu Mar 26 01:08:11 UTC 2009 i686 > > GNU/Linux > > $ egrep '_PAT(_| )' < /boot/config-2.6.26-2-686 > > # CONFIG_X86_PAT is not set
> PAT wasn't supported at all in 2.6.26. Mh, at least the configuration option is mentioned in the kernel config, even though it's disabled. > But it doesn't mean that it's the same than having PAT disabled in > 2.6.29 since the whole ioremap implementation has been intrusively > modified. I'm reporting back with some delay as I struggled a bit to produce a custom compiled 2.6.29 kernel - I was not prepared for the initrd and kernel-patch changes introduced by kernel-package 12 and documentation of the new behaviour is still rather sparse... I now rebuild the Debian 2.6.29 kernel source package using the same configuration as the official image, but I enabled PAT. Unfortunately PAT does not seem to be the (only) culprit, I still get: $ egrep 'tiling' < /var/log/Xorg.0.log (EE) intel(0): Failed to set tiling on front buffer: rejected by kernel (EE) intel(0): Failed to set tiling on back buffer: rejected by kernel (EE) intel(0): Failed to set tiling on depth buffer: rejected by kernel as with the original 2.6.29 image and Xorg compositing performance is still unusuably slow. $ uname -a Linux Zweiblum 2.6.29.debian.pat.20090418.1 #1 SMP Sat Apr 18 10:26:43 CEST 2009 i686 GNU/Linux $ egrep '_PAT(_|=| )' < /boot/config-2.6.29.debian.pat.20090418.1 CONFIG_X86_PAT=y $ egrep PAT < /var/log/dmesg [ 0.000000] x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106 [ 0.004000] x86 PAT enabled: cpu 1, old 0x7040600070406, new 0x7010600070106 Compared to the official 2.6.29 image, x11perf shows doubled performance: 1200000 trep @ 0.0218 msec ( 46000.0/sec): Char in 80-char aa line (Charter 10) However this is still several times slower than with the Debian kernel 2.6.26 image and does not improve usability. Greetings, Gunter
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