Re: [LAU] difference between realtime-kernel and low-latency-kernel?

On Wednesday 03 October 2007, Frank Barknecht wrote:

> Generally we have two kinds of kernels: The "vanilla" kernel as
> downloadable on kernel.org and the same kernel, but patched with Ingo
> Molnars RT-patches. The vanilla kernel, if configured properly with
> CONFIG_PREEMPT etc., already gives very good performance in the low
> latency department, enough for many users, even audio users. I run one
> of these.

Well, the vanilla kernel also has a CONFIG_HZ setting of i think 200hz per
default. This is too little timing resolution for processes that rely on the
system timer frequency being higher [some sequencers come to mind]..

The "lowlatency" kernel in ubuntu thus has CONFIG_HZ set to 1000 and
CONFIG_PREEMPT enabled.

This might be good enough for some people..

For a truly reliable system (where you can count on no audio period being
missed because you forgot to disable the damn updatedb cronjob) you need a
system patched with ingo's realtime preemption patches and have it properly
configured. E.g. situations where you record performances that are not
repeatable.. Or you cannot afford to have a click because your signal goes
over a 100000 Watt P.A. [Though i guess with vanilla jack you must not change
any connections during the task because this might cause lost buffers [due to
vanilla jackd doing some coarse grained locking], too - jackdmp might help]..

Regards,
Flo

-- 
Palimm Palimm!
http://tapas.affenbande.org
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