20 Jul
2011
20 Jul
'11
11:08 p.m.
For all here who don't follow the kernel lists..
Thomas Gleixner has announced a new version of the real-time patch:
https://lkml.org/lkml/2011/7/19/309
Even though most of the pro-audio-relevant preemt-rt patches are already
mainline since 2.6.39, this is still very interesting mostly because:
What's new in 3.0-rt ?
- No more split soft interrupt threads. We need to analyze whether
this is a good decision.
- softirq handling from the end of interrupt threads and on all
thread sites where a nested local_bh disabled section ends
...
..and this latency plot is stunning:
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-…
enjoy,
robin
21 Jul
21 Jul
12:36 a.m.
Excerpts from Robin Gareus's message of 2011-07-20 23:08:50 +0200:
For all here who don't follow the kernel lists..
Thomas Gleixner has announced a new version of the real-time patch:
https://lkml.org/lkml/2011/7/19/309
Even though most of the pro-audio-relevant preemt-rt patches are already
mainline since 2.6.39, this is still very interesting mostly because:
Thanks,
seems like significant changes were made in the smp department, let's
hope they work out.
The plot really does look stunning, strangly (?) not on other machines.
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-…
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-…
No idea what those plots tell about real world usage. It's good to get
another set of patches though.
Philipp
What's new in 3.0-rt ?
- No more split soft interrupt threads. We need to analyze whether
this is a good decision.
- softirq handling from the end of interrupt threads and on all
thread sites where a nested local_bh disabled section ends
...
..and this latency plot is stunning:
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-…
enjoy,
robin 
1:03 a.m.
On Thursday 21 July 2011, at 00.36.55, Philipp Überbacher
<hollunder(a)lavabit.com> wrote:
[...]
> ..and this latency plot is stunning:
> https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplo
> t-r4s6.0.html?latencies=&showno=&slider=57
[...]
The plot really does look stunning, strangly (?) not
on other machines.
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-
r4s7.0.html
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot
-r4s8.0.html
No idea what those plots tell about real world usage. It's good to get
another set of patches though.
In terms of worst case figures, these plots look a bit like what I've seen
with RT-Linux and RTAI on various hardware (PII/III workstations via Geode
SBCs through Intel Core based Celerons on industrial Mini-ITX boards), though
with "true" RT kernels, one tends to get a lot of very low latency points, and
only the occasional peak.
SBCs with lowpower CPUs (Geode and the like) tend to perform a lot worse than
"proper" laptop and desktop CPUs. Memory and/or cache bandwidth issues, maybe?
--
//David Olofson - Consultant, Developer, Artist, Open Source Advocate
.--- Games, examples, libraries, scripting, sound, music, graphics ---.
| http://consulting.olofson.net http://olofsonarcade.com |
'---------------------------------------------------------------------'
1:20 a.m.
Excerpts from David Olofson's message of 2011-07-21 01:03:32 +0200:
On Thursday 21 July 2011, at 00.36.55, Philipp
Überbacher
<hollunder(a)lavabit.com> wrote:
[...]
I do wonder whether the occasional peaks are due to the mainboards or
the CPUs. At least in the wild mainboards seem to have a lot of
influence (hardware interrupts or however they're called).
> ..and this latency plot is stunning:
> https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplo
> t-r4s6.0.html?latencies=&showno=&slider=57
[...]
The plot really does look stunning, strangly (?)
not on other machines.
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-
r4s7.0.html
https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot
-r4s8.0.html
No idea what those plots tell about real world usage. It's good to get
another set of patches though.
In terms of worst case figures, these plots look a bit like what I've seen
with RT-Linux and RTAI on various hardware (PII/III workstations via Geode
SBCs through Intel Core based Celerons on industrial Mini-ITX boards), though
with "true" RT kernels, one tends to get a lot of very low latency points, and
only the occasional peak.
SBCs with lowpower CPUs (Geode and the like) tend to perform a lot worse than
"proper" laptop and desktop CPUs. Memory and/or cache bandwidth issues, maybe?
4968
days inactive
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linux-audio-dev@lists.linuxaudio.org
3 comments
3 participants
participants (3)
-
David Olofson -
Philipp Überbacher -
Robin Gareus