** Description changed: - When comparing /proc/mtrr of intrepid and current jaunty i noticed there - is an entry missing. + [Impact] + This bug is one of a set of fairly serious issues that afflict -intel users on Jaunty. The problem is that X and the kernel are miscommunicating about MTRR's, and X ends up deleting ones it shouldn't. + + The user-visible effect of this is poor performance in video playback, + such as very choppy flash video. + + [Solution] + The solution for this issue is composed by a kernel patch and a xorg patch, both from the -intel upstream developers. Both of these patches are upstream, and currently included as of the 2.6.30 kernel and -intel 2.7.99.x in Karmic, which does not exhibit the bug. For Jaunty both of these need backported. + + Kernel patch: http://people.ubuntu.com/~apw/lp314928-jaunty/0001 + -UBUNTU-SAUCE-drm-i915-Set-up-an-MTRR-covering-the-GT.patch + + -intel patch: + http://launchpadlibrarian.net/28453154/122_dont_fixup_mtrrs_in_gem_config.patch + + The kernel patch sets the MTRR correctly and the Xorg patch assures that + reloading xorg doesn't wipe it. + + It's not necessary to roll out both patches simultaneously, but both + linux and -intel need their patches in order to make the bug be + resolved. + + [Test Case] + 0. Verify flash video playback is relatively okay + 1. Note contents of /proc/mtrr + 2. Restart xorg + 3. Note contents of /proc/mtrr again, and how it has changed since #1 + 4. See that flash video playback is laggy + + [Regression Potential] + Reasonably low. This change has been reviewed and tested upstream and in karmic for quite a while, and the specific patches being proposed in this SRU have been provided for testers via a PPA and verified to solve the bug. Due to the nature of the patch, it's not possible to prove definitively that it can't cause regression, so it would be advisable to test this thoroughly in jaunty-proposed. + + [Original Report] + When comparing /proc/mtrr of intrepid and current jaunty i noticed there is an entry missing. Intrepid: reg00: base=0x00000000 ( 0MB), size=1024MB: write-back, count=1 reg01: base=0x40000000 (1024MB), size= 512MB: write-back, count=1 reg02: base=0x5f700000 (1527MB), size= 1MB: uncachable, count=1 reg03: base=0x5f800000 (1528MB), size= 8MB: uncachable, count=1 reg04: base=0xb0000000 (2816MB), size= 256MB: write-combining, count=1 Jaunty: reg00: base=0x000000000 ( 0MB), size= 1024MB, count=1: write-back reg01: base=0x040000000 ( 1024MB), size= 512MB, count=1: write-back reg02: base=0x05f700000 ( 1527MB), size= 1MB, count=1: uncachable reg03: base=0x05f800000 ( 1528MB), size= 8MB, count=1: uncachable So I tried adding it back by using: sudo -s echo "base=0xb0000000 size=0x10000000 type=write-combining" > /proc/mtrr I have noticed a few things after adding that entry: - glxgears is now about twice as fast (I know its not a real benchmark ;) - 2D Performance does not seem affected however (just testing a bit with x11perf/gtkperf) - it fixes the corruption on the ttys (bug 312677) I also noticed that this entry gets removed everytime xorg gets restarted. But I'm not sure with all the recent changes in memory management if that entry should still be there or not. ------------- lspci 00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03) 00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03) 00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03) 00:1c.0 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 1 (rev 03) 00:1c.2 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 3 (rev 03) 00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 03) 00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 03) 00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 03) 00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 03) 00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 03) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d3) 00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 03) 00:1e.3 Modem: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Modem Controller (rev 03) 00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 03) 00:1f.2 IDE interface: Intel Corporation 82801FBM (ICH6M) SATA Controller (rev 03) 00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 03) 02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5751M Gigabit Ethernet PCI Express (rev 11) 04:00.0 CardBus bridge: Texas Instruments PCI4510 PC card Cardbus Controller (rev 03) 04:00.1 FireWire (IEEE 1394): Texas Instruments PCI4510 IEEE-1394 Controller (rev 01) 04:02.0 Network controller: Intel Corporation PRO/Wireless 2200BG [Calexico2] Network Connection (rev 05)
-- [i915GM] MTRR entry gets removed when restarting xorg - causes corruption on ttys https://bugs.launchpad.net/bugs/314928 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
