25 Mar
2004
25 Mar
'04
5:43 a.m.
Fernando Pablo Lopez-Lezcano <nando(a)ccrma.stanford.edu>du>:
Caveats: FC1 qt + dri + 2.6.4 + SCHED_FIFO = hanging
machine, as
reported a while back. Yuck. Turning off dri solves this one at the cost
of no acceleration.
With all the above I'm able to run Jack with SCHED_FIFO and no xruns in
a short test run at 64x2 (with a background task tar'ing /usr to a
file). But with DRI off, Qjackctl and some real Jack applications I do
get xruns even at 128x2, I guess my cpu is maxing out...
I'm confused. I probably have misunderstood something, but: First you say,
that you get a "hanging machine" with SCEHD_FIFO enabled applications, but
later you say that you can run Jack with SCHED_FIFO with all the different
configurations/kernels you mention.
What do you mean with a hanging machine? Do you get 'random' lockups, or
does your system hang always when some specific software is run with SCHED_FIFO?
Do you get lockups with this kernel & setup (option d in your email)?
Could you give a list of specific patches (and urls) you have applied to
2.6.4-1.286.2.ll (option d), or maybe a link to the source package?
Sampo
25 Mar
25 Mar
3:41 p.m.
New subject: [linux-audio-user] Re: Recent LKML discussion on preempt/latency in 2.6 kernels
On Thu, 2004-03-25 at 01:36, Sampo Savolainen wrote:
Fernando Pablo Lopez-Lezcano
<nando(a)ccrma.stanford.edu>du>:
The hangs were traced to a bad patch in the DRM modules (thanks to
Andrew Morton and Takashi Iwai for their help).
Caveats: FC1 qt + dri + 2.6.4 + SCHED_FIFO =
hanging machine, as
reported a while back. Yuck. Turning off dri solves this one at the cost
of no acceleration.
With all the above I'm able to run Jack with SCHED_FIFO and no xruns in
a short test run at 64x2 (with a background task tar'ing /usr to a
file). But with DRI off, Qjackctl and some real Jack applications I do
get xruns even at 128x2, I guess my cpu is maxing out...
I'm confused. I probably have misunderstood something, but: First you say,
that you get a "hanging machine" with SCEHD_FIFO enabled applications, but
later you say that you can run Jack with SCHED_FIFO with all the different
configurations/kernels you mention. What do you mean with a hanging machine? Do you get
'random' lockups, or
does your system hang always when some specific software is run with
SCHED_FIFO?
They only happen with the combination of stuff mentioned above. And they
are repeatable hangs. Actually they are not really hangs, they are Ooops
triggered by the CONFIG_DEBUG_SPINLOCK_SLEEP kernel option which detects
that a lock is being held while trying to reschedule.
The patch that "fixes" the latency problems with Radeon in the DRM
modules is bad (what changes from a) to b)). It was a literal
translation of a very old patch I had aquired somehow. But it does
something illegal (trying to reschedule while a lock is being held). So
the code will have to be rewritten somehow.
Do you get lockups with this kernel & setup
(option d in your email)?
Could you give a list of specific patches (and urls) you have applied to
2.6.4-1.286.2.ll (option d), or maybe a link to the source package?
I'd prefer to not propagate an obviously broken package :-)
I was adding:
realtime security module (LSM) 0.0.4
http://www.joq.us/realtime
low latency scheduling additions by Takashi Iwai
http://kerneltrap.org/node/view/2702
drm scheduling additions (radeon/mga/r128) --> broken!
I can send you the patches off the list if you want them.
That's all there is...
-- Fernando
5:11 p.m.
New subject: [linux-audio-user] Re: Recent LKML discussion on preempt/latency in 2.6 kernels
On Thu, Mar 25, 2004 at 11:35:26AM -0800, Fernando Pablo Lopez-Lezcano wrote:
I was adding:
realtime security module (LSM) 0.0.4
http://www.joq.us/realtime
low latency scheduling additions by Takashi Iwai
http://kerneltrap.org/node/view/2702
drm scheduling additions (radeon/mga/r128) --> broken!
What kind of latency were you getting with this, compared to patched 2.4?
- Steve
5:37 p.m.
New subject: [linux-audio-user] Re: Recent LKML discussion on preempt/latency in 2.6 kernels
On Thu, 2004-03-25 at 13:05, Steve Harris wrote:
On Thu, Mar 25, 2004 at 11:35:26AM -0800, Fernando
Pablo Lopez-Lezcano wrote:
Reposting:
a) preempt enabled, Takashi's patches included, x11 sucks...
http://www-ccrma.stanford.edu/~nando/latencytest/20040323/2.6.4-1.279.ll.cc…
b) preempt enabled, added tweaked radeon low latency patch, much better:
http://www-ccrma.stanford.edu/~nando/latencytest/20040323/2.6.4-1.279.ll.cc…
c) preempt disabled, with Takashi's and radeon patches:
http://www-ccrma.stanford.edu/~nando/latencytest/20040323/2.6.4-1.286.1.ll.…
d) same as c), with preempt enabled again:
http://www-ccrma.stanford.edu/~nando/latencytest/20040323/2.6.4-1.286.2.ll/
e) same as d), without loading the xfree86 dri module:
http://www-ccrma.stanford.edu/~nando/latencytest/20040323/2.6.4-1.286.2.ll.…
This is from the output of latencytest 0.52 and looks very good. But,
and it is not a small but, when I tried to use real jack and jack
applications I could not go down to 2x128 at all, kept getting small
xruns. But an idle jack at 2x64 plus disk activity ("tar cf usr.tar
/usr") would very seldom generate xruns.
So there is something else that needs tweaking[*].
Takashi's patches do improve the situation quite a lot.
-- Fernando
[*] plus my setup was not really that stable. For some reason depending
on how I had the hwconf setup done by kudzu (or not) I would get into
situations where moving the mouse was creating all sorts of small xruns
in an otherwise idle jack. That drove me nuts for the better part of a
day, where I could not get back to the nice "almost no xrun" situation
although I thought I was "undoing" everything I had done.
I was adding:
realtime security module (LSM) 0.0.4
http://www.joq.us/realtime
low latency scheduling additions by Takashi Iwai
http://kerneltrap.org/node/view/2702
drm scheduling additions (radeon/mga/r128) --> broken!
What kind of latency were you getting with this, compared to patched 2.4? 
8:55 p.m.
New subject: [linux-audio-user] Re: Recent LKML discussion on preempt/latency in 2.6 kernels
Fernando Pablo Lopez-Lezcano <nando(a)ccrma.stanford.edu> writes:
This is from the output of latencytest 0.52 and looks
very good. But,
and it is not a small but, when I tried to use real jack and jack
applications I could not go down to 2x128 at all, kept getting small
xruns. But an idle jack at 2x64 plus disk activity ("tar cf usr.tar
/usr") would very seldom generate xruns.
Thanks for the data, Nando.
I've been wishing for a version of that latencytest that uses JACK.
Scheduling latency problems are exacerbated by JACK's demanding
requirements.
Takashi's patches do improve the situation quite a
lot.
Y'all do good work. With continued attention of this caliber, I
expect we'll get to 2.4 levels before long.
--
joq
7641
days inactive
7641
days old
linux-audio-user@lists.linuxaudio.org
4 comments
4 participants
participants (4)
-
Fernando Pablo Lopez-Lezcano -
Jack O'Quin -
Sampo Savolainen -
Steve Harris