21 Dec
2005
21 Dec
'05
10:04 p.m.
On Thu, 22 Dec 2005 02:38:28 +0100
Sylvain Reynal <reynal(a)ensea.fr> wrote:
Hi,
Florian,
Is that to say that (cf. your tutorial,
http://tapas.affenbande.org/?page_id=6) reprioritizing IRQ handlers with
things like
chrt -f -p 97 `pidof "IRQ sound_car_irq"`
which prove so simple and efficient with an -rt kernel, are just pointless
with a preemptible kernel (assuming it was compiled with threaded IRQ
handlers)?
Which (compiling with threaded irq handlers) is only an option in a -rt
patched kernel. Vanilla doesn't have threaded IRQ handlers even in
"Preemptible Kernel" mode. Or so i seem to remember.
That'd confirm my recent measurements, but still i
can scarcely make out why
this is so.
I have no idea. I mostly only run Complete Preemption, which, when it
works, works great :) But from my understanding, unthreading the
soundcard IRQ handler or setting it to a high priority should be pretty
much equivalent from an enduser's point of view (Means: i have no clue,
but i bluntly assume). And at the time i actually used preemption modes
different from Complete Preemption for audio stuff, they were
equivalent.
And while we're at it, i get --amazingly enough--
far more xruns when
un-threading my PCI sound card IRQ handler (doing echo 0 > /proc/irq/...)
than when leaving it threaded...
Hmm, this is weird. I'm not sure. It would be best to ask Ingo directly
about this. Might be a regression.
Regards, Flo
--
Palimm Palimm!
http://tapas.affenbande.org