[LAU] 3.8 vs. 3.5 for realtime USB performance

[James Stone]

On Fri, Jun 28, 2013 at 7:49 PM, Fernando Lopez-Lezcano <
nando at ccrma.stanford.edu> wrote:

> On 06/28/2013 10:23 AM, Fernando Lopez-Lezcano wrote:
>
>> On 06/27/2013 04:24 PM, James Stone wrote:
>>
>>>
>>>
>>> On Sun, Jun 9, 2013 at 10:04 AM, Clemens Ladisch <clemens at ladisch.de
>>> <mailto:clemens at ladisch.de>> wrote:
>>>
>>>     James Stone wrote:
>>>     > I am struggling to get usable realtime performance <512 latency
>>> on my
>>>     > Ubuntu Studio "low latency" kernels 3.8... The 3.5 kernel in
>>> contrast works
>>>     > fine. I put a bugreport in with Ubuntu, but it seems like no-one
>>> else is
>>>     > reporting the same problem. Makes me wonder if I am doing
>>> something wrong.
>>>     > Is there anything additional I should be trying, or is this a
>>> known problem
>>>     > that is being worked on by the kernel devs?
>>>
>>>     You have to wait for the next stable kernel:
>>>     <http://git.kernel.org/linus/**e194401783<http://git.kernel.org/linus/e194401783>
>>> >
>>>
>>> Hi Clemens (and everyone else),
>>>
>>> This didn't fix the bug. See:
>>>
>>> https://bugs.launchpad.net/**ubuntu/+source/linux/+bug/**1191603<https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1191603>
>>>
>>> and:
>>>
>>> https://bugs.launchpad.net/**ubuntu/+source/linux-**
>>> lowlatency/+bug/1185563<https://bugs.launchpad.net/ubuntu/+source/linux-lowlatency/+bug/1185563>
>>>
>>> Do you have any thoughts? Is this a problem with alsa/jack (as seems to
>>> be being implied) or with the kernel?
>>>
>>
>> I'm building a kernel with the fix that's here:
>> https://bugs.launchpad.net/**ubuntu/+source/linux/+bug/**1136110<https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1136110>
>> It seems that it fixes the problem.
>>
>
> I can get 128x3 with no problems or glitches on an VSL181 USB2 interface.
> Anything lower does not work but this is perfectly usable (in a short test).
>
> -- Fernando
>


Hmm.. not tried that patch, but I tried the reverted kernel - which is the
fix they are pushing for that bug, and it doesn't help.

James
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