Re: [LAD] cpu spikes

First of all, for the record, anyone who equates firsthand experiences
with snakeoil, shall find their words completely ignored by yours truly :-)
> First of all, booting into console mode, rather than running the full
> blown desktop seemed to eliminate most of the problems, although it’s
> still not quite a stable as i’d like.
> Also i don’t quite understand how all of that could interfere with my
> RT-thread.
> This was going to try and install a more minimal system anyway, and
> don’t need a graphical environment for this, but during developments
> it’s kind of nice to have.
Check your processes with htop. Make sure none of the resources-eating
background items remain.
>
> I still would like to see how far i can take this, and was really
> hoping i can continuously use 80-90% of all cpu cores without dropouts…
> Is that realistic with a lowlatency kernel?
In my experiences this is not realistic with either a realtime kernel or
a lowlatency kernel, unless you can afford large latency times, using
large audio buffers. This is because in a low latency situation, the
CPU has to have a lot of free cycles available to be ready to handle
everything which comes.

I do think you will probably see more stability if you use JACK in such
efforts, or even PulseAudio, than if you use direct ALSA. I have found
ALSA to be great for drivers, not anywhere near so good for the
transport phases.
>
>> Cron should also be turned off, but that is probably not the problem
>> here. Cron runs super "nice" but there seem to be some things it does
>> like packge update that can cause problems too. I turn off cron while
>> recording.
I have never had to turn cron on an otherwise well-approached environment.
>
> I don’t have a wireless on my machine, nor an nvidia card. just intel
> builtin graphics. This where my linux knowledge falls short, but If i
> don’t have that hardware, can I assume no drivers for it are loaded?
Yep, no problem there.
>
>>
>> AFAIK, the important things are.
>>
>> 1. Use a properly configured realtime patched kernel.
>>
>
> lowlatency-kernel is not going to cut it?
Lowlatency is just fine if you have the CPU for it, and lowlatency is a
whole lot easier to set up now, with the Liquorix people on the ball
like they are.
> I wasn’t really able to find to much info on the difference between
> the two, other than than the rt-kernel is a “step up” and hard
> realtime vs soft.
> But nothing on how this is technically achieved
On my production box, with my Behringer Firewire FCA202, I have found
slightly better results using a Liquorix kernel than with a
realtime-patched kernel. Liquorix has a whole lot of interesting
optimizations. I would imagine that if my CPU were not what it is,
and/or the load type different, the differences would probably be
considerably greater, and I have no thought as to which side it would
land on.

-- 
Jonathan E. Brickman   jeb@email-addr-hidden   (785)233-9977
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Received on Thu Jan 28 16:15:01 2016