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#1 2014-07-12 15:57:38

Registered: 2014-07-12
Posts: 1

Intermittent Frame Rate drops on Intel i915

Hi all,

I'm trying to diagnose a very strange problem with my Dell L702x laptop

The symptoms:
The Intel GFX seem to cut out intermittently, resulting in drastic frame rate drops for all the open windows in the window manager. This usually happens when gaming, presumably because it's placing load on the Intel gfx chip (eg. Steam games such as Space Hulk, Anomaly Defenders and others will all cause this behaviour). Typically, I'm seeing 50-60fps drop to 5-10fps after 10-30mins gameplay, which then lasts 30s-5min, and then returns to 50fps. This repeats consistently, although the interval between frame rate drops seems to decrease after the first occurance (i.e the timeline is 30mins ok, 2mins bad, 5mins ok, 2mins bad, etc). Note that while the game triggers the behaviour, all windows are affected (so firefox becomes hard to interact with, etc).

Things tried so far:

  • Changing the  Option "AccelMethod" in /etc/X11/xorg.conf.d/20-intel.conf between sna|uxa|glamor

  • Changing some of the i915 driver options (enable_rc6=7 enable_fbc=1 lvds_downclock=1)

  • Running the git version of the xf86-video-intel package

  • Messing around with vblank in driconf

  • Monitoring /sys/kernel/debug/dri/0/i915_error_state - no errors logged

  • No errors logged to journalctl -xf

Hardware info:

[root@emerald ~]# cat /etc/X11/xorg.conf.d/20-intel.conf 
Section "Device"
   Identifier  "Intel Graphics"
   Driver      "intel"
   Option      "AccelMethod"  "uxa"
   #Option      "AccelMethod"  "sna"
   #Option      "AccelMethod"  "glamor"
   #Option      "TearFree" "true"
[root@emerald ~]# for i in /sys/module/i915/parameters/*; do echo $i=$(cat $i); done
[root@emerald ~]# pacman -Q |egrep "mesa|intel"
intel-dri 10.2.3-1
intel-tbb 4.2_20140601-1
lib32-intel-dri 10.2.3-1
lib32-mesa 10.2.3-1
lib32-mesa-libgl 10.2.3-1
libva-intel-driver 1.3.2-1
mesa 10.2.3-1
mesa-demos 8.2.0-1
mesa-libgl 10.2.3-1
xf86-video-intel-git 2.99.912.229.ge0523ad-1

Other notes:
This laptop also has an nVidia card (via Optimus/bumblebee) but I've noted this behaviour regardless of whether the nvidia card is on or off. I use XMonad as my window manager, so there's no compositing or similar going on.

Also, and this is the strangest thing, I can cause the frame rate to recover if I open a flash game in my browser on a second monitor (I normally use Gemcraft 2: Chasing Shadows on Armor Games for this purpose). I have *no* idea why this improves the framerate (not back to 50fs, but it will usually repair the 10fps back to ~30fps)

Any suggestions for DRI/X/module/kernel tweaks I can apply in order to improve this, or monitoring suggestions to catch the cause, are gratefully received smile



#2 2014-08-07 11:32:46

From: Denver Metro, CO, USA
Registered: 2014-04-11
Posts: 7

Re: Intermittent Frame Rate drops on Intel i915

intel_gpu_top from the intel-gpu-tools package might be helpful.

it's quite detailed, so you should at least be able to see what (if anything) changes during a slowdown.

                         my Arch machines:
Helicoid = Lenovo ThinkPad Helix | Moo = Gateway LT2032u | Vladimir = Custom Desktop | Dodecahedron = HP Pavilion m7650n


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