I got fed up with my 945gm not being capabile of 60fps glxgears.
commit d938da6b132a2d6addeba4c57a67ec3c07824843
Author: Ville Syrjälä <ville.syrj...@linux.intel.com>
Date: Fri Mar 22 20:08:03 2019 +0200
drm/i915: Disable C3 when enabling vblank interrupts on i945gm
The main difference compared to the older pm_qos attempts is that I
found a way to dig out the exact c3 disable latency, so we should have a
reasonable guarantee that we do disable c3 but not c2. The power cost of
not using c3 seems to be about 0.7W on my machine (with the display on),
so this isn't exactly cheap :(
I did spend quite a bit of time at some point digging through the
chipset docs (such as they are). It's been a while since I did that but
I'll try to summarize what I recall; Gen3 introduced some kind of new
mechanism by which the gmch can wake up the CPU. The old AGPBUSY/PM_BUSY
involved the ICH as well IIRC, whereas the new mechanism supposedly does
not. IIRC the new mechanism already appears in the i915gm docs, but my
theory is that i945gm is where it actually got into use and either it is
broken or we're missing some magic undocumented bit somewhere. I did try
(blindly if necessary) poking at various registers that seemed relevant.
Alas, I was unable to find a magic bit to make C3+vblank interrupts
cooperate.
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https://bugs.launchpad.net/bugs/1087582
Title:
[gen3] Bad GPU performance whilst CPU is in deep sleep
Status in xf86-video-intel:
Fix Released
Status in xserver-xorg-video-intel package in Ubuntu:
Incomplete
Bug description:
I have an Acer AOD250(KAV60) netbook.
On Ubuntu 12.10 with glxgears I get 50-60 fps, while on Lubuntu I get half
that and sometimes worse.
The odd thing about this is that when I start moving my mouse around it
straightens up and goes back to roughly 55-60 fps, and once I stop moving the
mouse, the performance drops again.
I know the chipset and GPU isn't the best out there, but it shouldn't be
acting like this(before, I was able to use Celestia with ease but now I get
below 5 fps).
Latest available BIOS(v1.29)
Intel Atom N270 1.6GHz(1 core, 2 threads)
1024RAM
Intel 945GMA(8MB VRAM from BIOS)
Tested glxgears from mesa-utils "8.0.1+git20110129+d8f7d6b-0ubuntu2"
ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: xserver-xorg-video-intel 2:2.20.9-0ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-19.30-generic 3.5.7
Uname: Linux 3.5.0-19-generic i686
ApportVersion: 2.6.1-0ubuntu6
Architecture: i386
Date: Fri Dec 7 02:37:04 2012
InstallationDate: Installed on 2012-12-07 (0 days ago)
InstallationMedia: Lubuntu 12.10 "Quantal Quetzal" - Release i386 (20121017.1)
MarkForUpload: True
SourcePackage: xserver-xorg-video-intel
UpgradeStatus: No upgrade log present (probably fresh install)
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