Re: [LAU] vanilla kernel question

On Thu, 2009-10-08 at 23:11 -0500, Josh Lawrence wrote:
> all of the recent talk about kernels has raised a question in my mind:
>
> if you are running a vanilla kernel (that is, without the realtime
> patch), do the typical pam settings made in limits.conf still apply?
>
> @audio - rtprio 99
>
> since there is no "realtime" patch, would the rtprio setting become pointless?

No.

They are two unrelated issues. Setting limits in limits.conf
appropriately will allow your non-root accounts (that belong to that
group in this case) to use the SCHED_FIFO or SCHED_RR scheduler
algorithms so that they have always priority over other applications
running in the normal SCHED_OTHER scheduler. You always need that so
that it is less likely that your soundcard will run out of samples (with
properly designed software like Jack) because some other, less critical
application(s), is(are) using a lot cpu power available.

The rt patch makes latency inside the kernel smaller. So that the
scheduler that "slices" the available processor(s) time between
applications will not have to wait a long time to be able to do that.
The smaller the latency the smaller the buffers you can use in your
audio application.

Both are needed for best performance (but you won't go very far without
the SCHED_FIFO or SCHED_RR schedulers).

-- Fernando

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Received on Fri Oct 9 08:15:01 2009