28 Feb
2007
28 Feb
'07
9:54 a.m.
Hi
I'm considering getting a dual-core desktop machine for audio work. But
I'm wondering how well the two cores would be used for audio work. For
instance can clients running on different cores connect to the same jack?
Apparently I'm pretty ignorant concerning dual-core in the first place.
Is there any online info I should/could read that would give some
insight on how an audio environment is setup and performs on dual core?
--
peace, love & harmony
Atte
http://www.atte.dk | quintet: http://www.anagrammer.dk
| compositions: http://www.atte.dk/compositions
28 Feb
28 Feb
10:49 a.m.
Le 28 Feb à 14:54, Atte André Jensen ecrivait:
I'm considering getting a dual-core desktop
machine for audio work. But
I'm wondering how well the two cores would be used for audio work. For
instance can clients running on different cores connect to the same
jack?
Hi Atte.
This is completely transparent for the user and the applications
and works great, without any problem or particular setup (maybe for a
single dual core processor a SMP kernel is required).
I'd suggest you to consider Opteron.
Cheers,
Y.
6:36 p.m.
Yves Potin wrote:
This is completely transparent for the user
and the applications
and works great, without any problem or particular setup (maybe for a
single dual core processor a SMP kernel is required).
Ok that sounds good. How is it decided which app is running on which
core and can a running app (realtime audio) switch core?
--
peace, love & harmony
Atte
http://www.atte.dk | quintet: http://www.anagrammer.dk
| compositions: http://www.atte.dk/compositions
6:57 p.m.
On Wed, 2007-02-28 at 23:25 +0100, Atte André Jensen wrote:
Yves Potin wrote:
scheduling of processes on an SMP system is essentially completely
transparent to the user and the processes.
there are some tricks in modern linux systems that can be used to
circumvent the normal decisions of the operating system's scheduler, but
in general these are not going to be useful unless you really, really
know what you are doing.
--p
This is completely transparent for the
user and the applications
and works great, without any problem or particular setup (maybe for a
single dual core processor a SMP kernel is required).
Ok that sounds good. How is it decided which app is running on which
core and can a running app (realtime audio) switch core? 
1 Mar
1 Mar
10:07 a.m.
Hi,
Paul Davis skrev:
On Wed, 2007-02-28 at 23:25 +0100, Atte André Jensen
wrote:
Possibly I'm missing something here, but I was under the impression that
to _really_ utilize a dual core system you need to use Jackdmp.
Jackd will only use one core. The other core won't be without work
though, there's plenty of work to redraw gui's and what not.
Someone do correct me if I'm wrong.
Regards,
Robert
Yves Potin wrote:
scheduling of processes on an SMP system is essentially completely
transparent to the user and the processes.
there are some tricks in modern linux systems that can be used to
circumvent the normal decisions of the operating system's scheduler, but
in general these are not going to be useful unless you really, really
know what you are doing.
--p
This is completely transparent for the
user and the applications
and works great, without any problem or particular setup (maybe for a
single dual core processor a SMP kernel is required).
Ok that sounds good. How is it decided which app is running on which
core and can a running app (realtime audio) switch core?
10:18 a.m.
On Thu, 2007-03-01 at 15:06 +0100, Robert Jonsson wrote:
Possibly I'm missing something here, but I was
under the impression that
to _really_ utilize a dual core system you need to use Jackdmp.
Jackd will only use one core. The other core won't be without work
though, there's plenty of work to redraw gui's and what not.
Someone do correct me if I'm wrong.
no, thats basically correct. in jackd, the JACK threads of every client
will be serialized. this means that audio processing will happen on one
CPU at a time (not necessarily the same one). as you said, however, this
hardly means that the other CPU(s) are idle, they just don't get used
for audio processing.
note that jackdmp can only use more than 1 CPU if there are parallel
data flows in the audio connections. for example, this will not use
multiple cores:
freqtweak -> sooperlooper -> timemachine
neither will
ardour -> jamin
however, this will:
zynaddsubfx ----+
|
+------> ardour
|
bristol --------+
audio data processing is rarely as inherently parallel as, say,
graphics.
--p
6:18 p.m.
Robert Jonsson wrote:
Possibly I'm missing something here, but I was
under the impression that
to _really_ utilize a dual core system you need to use Jackdmp.
You make it sound like I should have second thoughts before using
jackdmp. It's not a drop-in replacement for jack, or? Will regular jack
clients (ardour, zyn, specimen, ams) run on top of jackdmp? Other
show-stoppers regarding jackdmp?
--
peace, love & harmony
Atte
http://www.atte.dk | quintet: http://www.anagrammer.dk
| compositions: http://www.atte.dk/compositions
28 Feb
28 Feb
6:58 p.m.
Le 28 Feb à 23:25, Atte André Jensen ecrivait:
Ok that sounds good. How is it decided which app is
running on which
core and can a running app (realtime audio) switch core?
It's the task of the system, you have absolutely no control on
that. I can see very often a core taking the following of a process which
previously ran on another one (a core or a CPU because my PC has two
processors). I *never* take care of that, I just have a gkrellm to show me
what's happening. And I'm very happy with that :).
Y.
7:05 p.m.
On Wed, 28 Feb 2007 23:58:31 +0100
yves(a)jazzcomputer.org (Yves Potin) wrote:
Le 28 Feb à 23:25, Atte André Jensen ecrivait:
I have the same situation with a dual core athlon. I find CPU 0 seems
to do slightly more work than CPU1 (as shown by gkrellm) but sometimes
the processors seem to swap places.
So far, the only app that seems to have had more problems than on my
old single core 32bit athlon is ZynAddSubFX. It seems a little more
twitchy if I alter things while it is playing :(
--
Will J G
Ok that sounds good. How is it decided which app
is running on which
core and can a running app (realtime audio) switch core?
It's the task of the system, you have absolutely no control on
that. I can see very often a core taking the following of a process which
previously ran on another one (a core or a CPU because my PC has two
processors). I *never* take care of that, I just have a gkrellm to show me
what's happening. And I'm very happy with that :).
Y. 
10:08 p.m.
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On Wed, Feb 28, 2007 at 02:54:28PM +0100, Atte Andr? Jensen wrote:
Hi
I'm considering getting a dual-core desktop machine for audio work. But
I'm wondering how well the two cores would be used for audio work. For
instance can clients running on different cores connect to the same jack?
Apparently I'm pretty ignorant concerning dual-core in the first place.
Is there any online info I should/could read that would give some
insight on how an audio environment is setup and performs on dual core?
My advice would be: be very careful before choosing your hardware.
If I were doing it all over again, I'd have first checked with the developers of
jackmp, jackd, and all the important hardware-dependent drivers (i.e. your audio card),
and find out EXACTLY what CPU, motherboard, and peripherals they have, and purchase *only*
an exact clone of their hardware. Unless you want to be on the bleeding edge and/or have
great coding/debugging skills.
The problem is that jackd apparently only uses one CPU, so the other CPU is basically
running "everything else" that isn't jack-related or RT. Good, but not
great. jackdmp seems really promising, is apparently is multithreaded for use on dual-core
machines, but I haven't been able to use it yet because its freebob support has only
been recently added. It probably won't be shaken out until someone can give the
developers a machine with the same CPU as I have, and I don't have that kind of money
sitting around.
That said, after shaking stuff out, and lots of great help from the developers, I've
figured out where my limits are (no more than one softsynth at a time, no more than 3-4
LADSPA plugins at a time), and I am happily making music on a Mac Mini Intel Core Duo
1.66Ghz with 2GB RAM.
But if I had to do it all again, I would have just bellied up to the bar next to one the
developers, and told the bartender, "I'll have what he's having".
- -ken
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linux-audio-user@lists.linuxaudio.org
9 comments
6 participants
participants (6)
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Atte André Jensen -
Folderol -
Ken Restivo -
Paul Davis -
Robert Jonsson -
yves＠jazzcomputer.org