For the first reference, I have a WoW install. I haven't seen fps below 60 except in areas of the game where there are a lot of other players, but that was under OpenGL back before the latest patch. I haven't tried since Blizzard has disabled all high end settings in OpenGL mode for both Windows and Linux, and I've heard nothing but bad performance on D3D recently. I could give it a shot though. What is needed to make a kernel realtime other than adding CONFIG_SCHED_DEBUG and adding the sysctl settings?

Thanks

Tom


On Mon, Oct 25, 2010 at 6:26 PM, Dan Kegel <dank@kegel.com> wrote:
Hey folks,
I've run into two web sites that claim that the Linux kernel causes performance
problems in particular games (see below). ��Anybody know of others?

And has anybody found concrete improvements in performance
of a particular app (other than an audio workstation app) from using
a realtime kernel?

Thanks!
- Dan

First:

http://wiki.archlinux.org/index.php/World_of_Warcraft#Kernel_Timing_Bug
says in a section dated September 2008:
"If you are having problems with choppy video every 15 seconds or so,
it is related to the kernel scheduler...
to fix, add CONFIG_SCHED_DEBUG=y to your kernel config, then set
kernel.sched_features=21
kernel.sched_batch_wakeup_granularity_ns=25000000
kernel.sched_min_granularity_ns=4000000
in /etc/sysctl.cfg."

Yikes. ��Any truth to that rumor?

Second:

http://hisouten.koumakan.jp/wiki/Linux_support#Resolved_bugs
says

"The game runs too slowly
Symptoms:
Instead of running at about 60-62fps, like the game is supposed to,
it'll run closer to 53fps. This is not ideal.
The bug:
This is a Linux timing issue. The game runs a secondary timing thread
with THREAD_PRIORITY_TIME_CRITICAL, where it simply sleeps for 16ms
and sends events to the main thread to tell it that a new frame is
needed. On Linux the necessary timing accuracy is not available, so it
wavers between 16ms and 20ms.
The fix:
I hacked around this by setting the timer period to 14ms. This leads
to a steady 62-63fps. Which is close enough for use, really. For a
constant 60fps turn on vsync in your video drivers."