Re: Disable kscand/Normal?

[Lee Revell]

On Wed, 2004-08-25 at 23:54, HOLTZ, CORBIN L. (JSC-ER) (LM) wrote:
> I'm currenty
> building a realtime visualization system for a Space Shuttle landing
> simulator at NASA.  I'm using a small network of 5 Pentium 4 computers
> running RedHat's 2.4.20-31.9 kernel.  I'm easily running 60 frames/second on
> my systems, but I'm having a problem because the kscand/Normal thread comes
> in every 25 seconds and causes me to drop a frame (very annoying).  I've
> looked into the kernel source and found where the kscand threads are
> spawned.  I also see where the 25 second period is coming from.  What I'm
> wondering is what would happen if I disabled the kscand/Normal thread?  I've
> got plenty of memory, and my process is the only thing running on the
> system.  Would I eventually see problems, or would I be OK since I'm not
> running low on memory?  What if I modified the kernel to allow me to
> temporarily disable the thread while my application is running (using a
> /proc file or something similar)?

You should also look into Ingo Molnar's voluntary preemption patches for
a more general way to do soft and even hard realtime with Linux.  Con's
suggestion will probably solve the kscand problem but the voluntary
preemption patches provide a more general way to deal with real time
constraints.  Check the LKML archives for the past few months, there has
been a lot of work in this area lately.

Lee

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