Re: [linux-audio-user] Re: favorite window Manager for making music?

From: Jan Depner <eviltwin69@email-addr-hidden>
Date: Tue Feb 21 2006 - 21:19:23 EET

On Mon, 2006-02-20 at 13:57 -0800, thewade wrote:
> Quoting Jan Depner <eviltwin69@email-addr-hidden>:
>
> > On Mon, 2006-02-20 at 08:24 -0800, thewade wrote:
> >> Quoting Ismael Valladolid Torres <ivalladt@email-addr-hidden>:
> >> >
> >> > If you're trying to get the lowest latency posible it's dumb having a
> >> > desktop system that eats half your resources.
> >> >
> >>
> >> I think what Lee is saying is that with realtime-lsm (and ingo's
> >> spin-locking?), jackd, your audio apps, and limits.conf all set up
> >> right all processes bow to your audio apps. So audio will still get the
> >> lowest latency possible independant of other threads running on your
> >> machine, including the window manager. The screen may not refresh as
> >> frequently or be as responsive, but you should incur no addidional
> >> XRUNS from using one window manager over another.
> >> Am I right?
> >>
> >
> > This is all well and good but you're only talking about CPU. Disk
> > I/O is another story entirely. If your WM starts doing some I/O that
> > you weren't aware of you may get an xrun because you couldn't access the
> > disk in time. This is the reason that I kill syslogd before I record.
> > Granted, generally speaking you'll do OK due to the priority of your
> > process but disk I/O takes a certain amount of time and you can't
> > interrupt it once it's gone to the disk.
>
> I think you can tweak the disk write interupt length so that disk write
> sizes are smaller and more frequent, which would effectively solve this
> problem.
> I think you can do this in /etc/sysconfig/harddisks in Fedora.
> Syslogd can be usefull...
>

    Not when I'm recording someone else's band and xruns make
Linux/Ardour/JACK look bad. There's nothing happening on my system that
I need to know about that badly. Especially after the fact.

> There is a hard drive realtime audio howto somewhere on the net: I
> remember reading it somewhere... I think Takashi Iwa (I hope I spelled
> his name right) wrote something about it when he wrote that latency
> motior kernel module tool thingy.
>

    There's a bunch of information on that on my site (albeit outdated).
Tuning the disk drives is a must and it *will* help but there are
instances where the disk drive is busy and you can't get to it no matter
how well tuned it is. I prefer to minimize any chance of that. You
have to remember that unless you're running RTLinux or VXWorks (or DOS
or VMS) you're not running a hard real time system. Shit happens.

-- 
Jan 'Evil Twin' Depner
The Fuzzy Dice
http://myweb.cableone.net/eviltwin69/fuzzy.html
"As we enjoy great advantages from the invention of others, we should be 
glad of an opportunity to serve others by any invention of ours, and 
this we should do freely and generously."
Benjamin Franklin, on declining patents offered by the governor of 
Pennsylvania for his "Pennsylvania Fireplace", c. 1744
Received on Sun Feb 26 20:18:08 2006

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