Re: [patch] Real-Time Preemption, -RT-2.6.12-rc6-V0.7.48-00

From: Ingo Molnar
Date: Fri Jun 17 2005 - 06:14:10 EST

* K.R. Foley <kr@xxxxxxxxxx> wrote:

> Just had an opportunity to check this. Everything does indeed seem to
> be working OK with this disabled. No lock up messages, no perceived
> problems.

btw., you have this enabled in your config:


this causes old-style spinlocking to be activated by default. I.e. you
dont get most of the benefits of PREEMPT_RT. You can reactivate it via:

echo 1 > /proc/sys/kernel/preempt_locks

but obviously this runtime flag involves some runtime overhead in the
locking code. This .config option is mainly meant to enable the
measurement of the locking overhead of PREEMPT_RT, and to debug boot
problems that might be related to PREEMPT_RT locking. So you'd almost
always want to run with DEBUG_RT_LOCKING_MODE turned off.

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