8 Aug
2008
8 Aug
'08
12:06 p.m.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
krgn wrote:
one or 2 quick addedums:
ubuntu hardy kernel works great for me. it is presumably compiled with a
different version of gcc, 4.2.3. could this be the source of the problems?
maybe, maybe not. it depends on compiler flags. That may be a question
for gcc specialists on the linux-rt-user mailing list.
I start to think we're chasing two independent but related bugs:
/something/ inside the kernel is triggered by invalid user setup. eg.
RT-priority inversion.
On Thu, Aug 7, 2008 at 11:56 PM, krgn
<k.gebbert(a)gmail.com> wrote:
> I did test with a few other versions of config, patchset and kernel sources
> but keep running into problems. I can't seem to be able to produce something
> that works reliably, all of the kernels run around 30 to 45 minutes with
> around 65 - 70% load on jackd and then hard lock. Since this machine I am
> using is pretty new, and I am havn't really run rt-linux on this one
> extensivly yet (partly because its almost not necessary with current stock
> debian kernels anymore), it could be something about the hardware, although
> it seems unlikely. Its a T61 T5500 with 1G Ram fwiw. With this in mind I
> think I should ask for some advice on what people consider sane values for
> important scripts, pam etc. My /etc/security/limits.conf looks like this:
>
> @audio - rtprio 99
> @audio - nice -15
> @audio - memlock 1024000000
i use
@audio - rtprio 90
@audio - nice -5
@audio - memlock 1400000
The man page says memlock's unit is KB not bytes.
IIRC someone said it's actually pages, but I did not check the source.
> What values do people use, and why? Are these sane
values?
I think so.
rtprio ranges from 1 to 99 and it does not matter how big the difference
is; as long as a value is larger it will "win" against lower values -
for SCHED_FIFO that is. - many suggest to leave a little "headroom"; it
does not need to be 99.
> What are the rtirq settings that are
> considered safe?
100 > timer-prio > sound-card-prio > jackd-process prio > 0
with a UA-25 on USB I use:
rtirq: reset [softirq-timer] pid=6 prio=1: OK.
rtirq: reset [softirq-timer] pid=11161 prio=1: OK.
rtirq: start [softirq-timer] pid=6 prio=99: OK.
rtirq: start [softirq-timer] pid=11161 prio=99: OK.
rtirq: start [rtc] irq=8 pid=2397 prio=90: OK.
rtirq: start [uhci_hcd:usb3] irq=22 pid=1066 prio=89: OK.
rtirq: start [i8042] irq=1 pid=330 prio=87: OK.
rtirq: start [i8042] irq=12 pid=329 prio=86: OK.
and run /usr/bin/jackd -R -P70 ...
<bit-off-topic>
@audio /usr/bin/jackd nice=-1 rtprio=85
@audio /usr/bin/qjackctl nice=-1 rtprio=84
@audio /usr/bin/ardour nice=-1 rtprio=83
@audio /usr/bin/hydrogen nice=-1 rtprio=82
as found on
http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel
is IMHO nonsense - in fact wrong: ONLY the jack-realtime callback should
have elevated priority. The audio-process-callback of the applications
will inherit this priority.
The above example would prefer GUI or JACK-stdio/log over disk-I/O.
There are use-cases where you may want to give an older-RTC-based
MIDI-application realtime priority. JACK-midi solves that for good.
</bit-off-topic>
> For now, I switched it off,
makes sense to debug&trace.
> yet I can see how it could be
> useful/necessary for certain setups, and don't want to rule it out
> completely. I start jackd oh hw:1 (hdsp multiface) with the following
> parameters:
>
> /usr/bin/jackd -R -P89 -m -dalsa -dhw:1 -r48000 -p128 -n2 -Xseq
now it clicked in the back of my head: there was something like
subtracting or adding 10 from the rt-priority in qjackctl, or jackd.
just a shot in the dark: jackd itself starts a couple of threads with
different priorities. I never cared since it just worked (and still does
on 2.6.24-rt3). - later today I'll be looking at jackd.
Meanwhile, does anyone here know about changes in the scheduler,
priority inversion etc of 2.6.26 ?
For high-level tests it may be interesting if a 2.6.26-rtX would run
stable if it does not do any audio or RT at all - just to double-back.
same without ACPI. for all we know this could well be caused by the
keyboard or some tty driver, no? I wish I had more machines to test ;)
puh, sorry for another long email - i got carried away.
robin
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
iEYEARECAAYFAkicUs4ACgkQeVUk8U+VK0LcGwCgwR6VIOLUN7YUGvS/0vEPpn+Q
PNkAnR+c2CeekQUK89S65FTtIeAqB1BU
=ZidW
-----END PGP SIGNATURE-----