linuxaudio.org

Hi Ralf,
On 05/08/2012 12:14 PM, Ralf Mardorf wrote:

quoted text
> On Mon, 2012-05-07 at 14:54 +0200, Robin Gareus wrote:

>> With linux >= 3.0 and the preemt-RT patch, you don't need the

>> 'threadirq' option with CONFIG_FORCE_THREADIRQ=y:

OOPS. Sorry about the typos above. That should have been 'PREEMPT_RT',

'threadirqs' and 'CONFIG_IRQ_FORCED_THREADING'.
>> http://anonscm.debian.org/viewvc/kernel/dists/trunk/linux-2.6/debian/pat...

quoted text
>

> So when I build a kernel-rt ex 3.0 from kernel.org source I need to use

> boot option threadirqs, if it isn't patched?

What is "kernel-rt ex 3.0" ??
https://www.kernel.org/pub/linux/kernel/projects/rt/3.[024] includes

that patch. It's not debian specific but part of Thomas Gleixner's

PREEMPT_RT patch. (It's just that debian's SCM viewer is the only one I

know that allows to read the [PREEMT_RT split quilt queue] patches in a

browser.)
> On AV Linux I run the 3.0.23-avl-7-pae with and the self-build

quoted text
> 3.0.23-rt40 without threadirqs. This way there's no difference between

> those kernels. I can't make music using JACK1 (didn't test JACK2 until

> now with AV Linux).

>

> But at least kernel-rt < 2.6.39 are ok without threadirqs ;)?

Correct. IIRC the 'threadirq' option was introduced in vanilla 2.6.39

when a large part of the tasklet-threading code was merged into Linus'

tree. This option was not present for linux-kernels (incl PREEMPT_RT

patched kernels) before 2.6.39.
> But CONFIG_IRQ_FORCED_THREADING has to be set for a kernel-rt too?
You don't really have no choice:
When you configure your kernel with the PREEMPT_RT patch,

PREEMPT_RT_FULL depends on CONFIG_IRQ_FORCED_THREADING and forces it

anyway (PREEMPT_RT_BASE does not).
> spinymouse@precise:~$ grep FORCE /media/avlinux/boot/config-3.0.23-rt40

quoted text
> CONFIG_IRQ_FORCED_THREADING=y

If you compile a recent kernel (>=3.0) with the PREEMPT_RT patch and set

"CONFIG_IRQ_FORCED_THREADING=y", the boot-option 'threadirqs' is implied

and using it makes no difference.
ciao,

robin

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