Known issues with ubuntu/kubuntu 64 bit

[salsaman]

Hi,
I was wondering whether there were any known issues with jack under 64 bit
ubuntu ? Sorry, I don't have version numbers, but some of my users are
reporting intermittent "noise" during playback. I can almost eliminate
code errors, since I have previously tested under 64 bit without problems.

Regards,
Gabriel "salsaman"
http://lives.sf.net


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[Paul Davis]

On Mon, 2008-07-21 at 17:19 +0200, salsaman@... wrote:
> Hi,
> I was wondering whether there were any known issues with jack under 64 bit
> ubuntu ? Sorry, I don't have version numbers, but some of my users are
> reporting intermittent "noise" during playback. I can almost eliminate
> code errors, since I have previously tested under 64 bit without problems.

i run jack on 64 bit all day. not ubuntu but its hard to see how that
would play a role. there are no known issues i can think of.


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[Quentin Harley]

Paul Davis wrote:

> On Mon, 2008-07-21 at 17:19 +0200, salsaman@... wrote:
>  
>> Hi,
>> I was wondering whether there were any known issues with jack under 64 bit
>> ubuntu ? Sorry, I don't have version numbers, but some of my users are
>> reporting intermittent "noise" during playback. I can almost eliminate
>> code errors, since I have previously tested under 64 bit without problems.
>>    
>
> i run jack on 64 bit all day. not ubuntu but its hard to see how that
> would play a role. there are no known issues i can think of.
>  

So do I. (64 Studio)

No problems here...

Cheers,
Quentin
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[Daniel James-2]

Hi Gabriel,

>> i run jack on 64 bit all day. not ubuntu but its hard to see how that
>> would play a role. there are no known issues i can think of.
>>  
> So do I. (64 Studio)
>
> No problems here...

There are a few issues which affect performance on Ubuntu specifically.
One is that Hardy Heron uses kernel 2.6.24, and there's a known
regression in realtime audio performance with that release, compared to
2.6.23 and earlier kernels.

Another possible reason is that the realtime kernel package in Ubuntu
universe is not quite so aggressively configured as the one we use in 64
Studio.

And finally, the version of jackd in Hardy is 0.109.2, and we know
that's not as reliable as the 0.103.0 that we use in our stable branch.

Cheers!

Daniel
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[Sébastien THOMAS-2]

Hi,

Le 22 juil. 08 à 11:15, Daniel James a écrit :

Hi Gabriel,

i run jack on 64 bit all day. not ubuntu but its hard to see how that

would play a role. there are no known issues i can think of.

  

So do I. (64 Studio)

No problems here...

There are a few issues which affect performance on Ubuntu specifically. One is that Hardy Heron uses kernel 2.6.24, and there's a known regression in realtime audio performance with that release, compared to 2.6.23 and earlier kernels.

What about 2.6.22 ( 2.6.22-14-rt) ? 

Another possible reason is that the realtime kernel package in Ubuntu universe is not quite so aggressively configured as the one we use in 64 Studio.

Could you be more verbose here ? Do you have any advice to give regarding the Ubuntu RT tuning so it can be as aggressive as 64 Studio ?

Many thanks.

--

Sébastien THOMAS - Ingénieur Systèmes

sebastien.thomas@... - tel : [phone]

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[Daniel James-2]

Hi Sébastien,

>> One is that Hardy Heron uses kernel 2.6.24, and there's
>> a known regression in realtime audio performance with that release,
>> compared to 2.6.23 and earlier kernels.
> What about 2.6.22 ( 2.6.22-14-rt) ?

It should be better; we still use 2.6.21-rt in our stable branch, on the
'if it ain't broke don't fix it' principle.

>> Another possible reason is that the realtime kernel package in Ubuntu
>> universe is not quite so aggressively configured as the one we use in
>> 64 Studio.
>
> Could you be more verbose here ?

I'm referring in particular to this kernel config setting:

Preemption Mode (Complete Preemption (Real-Time))

I'm not sure if Ubuntu's RT kernel uses that setting.

> Do you have any advice to give
> regarding the Ubuntu RT tuning so it can be as aggressive as 64 Studio ?

There's a useful page here:

http://devel.goto10.org/puredyne/wiki/KernelAndSystemOptimization

We've been talking to the pure:dyne team about having a new
linuxaudio.org mailing list for distro building and tuning issues,
because at the moment we're all working to solve the same problems, and
so there's a lot of duplicated effort.

Cheers!

Daniel

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