8 May
2012
8 May
'12
3:11 p.m.
Hi Ralf,
On 05/08/2012 12:14 PM, Ralf Mardorf wrote:
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'.
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
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
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