Subject: Re: [linux-audio-dev] Newbie question
From: yodaiken_AT_fsmlabs.com
Date: Tue Jul 11 2000 - 00:41:27 EEST
On Mon, Jul 10, 2000 at 06:40:21PM +0000, Erik de Castro Lopo wrote:
> Luis Pablo Gasparotto wrote:
> >
> > Hi all,
> >
> > I´m a newbie in Linux Audio and I want to ask you some questions:
> >
> > 1) Wich´s the windows latency?
>
> Who cares :-)
>
> > 2) Advantages and disadvantages of RTLinux ? How it works? Differences
> > between Linux and RTLinux?
>
> RTLinux is a real time kernel which runs the Linux kernel as one of
> its processes. The main problem with RTLinux form the point of view
> of audio applications is that it RTLinux does not have all of the
> operating systems services that you would expect from an OS. For
> instance, it is my understanding that disk access is not possible
> from RTLinux. Instead data has to be read from/written to a pipe
> with a process under Linux doing the disk I/O.
There are several ways of doing this, and it is not very hard, but
you touch on on the reason why RTLinux can offer consistent bounded
worst case timing. The reason is that the RT component is decoupled from
the non-RT operating system so that no RT component ever is forced to wait
for a non-RT operation. Most file systems are inherently non-realtime: they
get high performance from doing tricks like re-ordering disk operations,
caching names ...
So RTLinux separates the two to get better RT performance at the cost
of requiring programmers to understand what parts of their code have
RT constraints and what parts do not.
>
> > 3) Why Ingo´s patches don´t go to mainstream?
>
>
> I see Ingo's patch as a proof of concept thing. Many on the lkml
> saw the patch as a rough hack (which Ingo agrees with) and therefore
> not suitable for going strait into the kernel.
>
> However, there was extensive discussion about this on the lkml and
> it looks like these issues will be looked at and dealt with even
> if Ingo's patch isn't accepted as is.
>
> > Is there other possible solution to real time in Linux?
>
> There are one or two RTLinux work-alikes. One is named KURT;
> try search for it on google.
The authors of KURT refer to it as "firm" realtime and it is not
a work alike.
>
> Erik
> --
> +-------------------------------------------------+
> Erik de Castro Lopo erikd_AT_zip.com.au
> +-------------------------------------------------+
> Peter F. Curran : Microsoft. Still delivering a text editor with
> Win95/98 that can only open a max 64K file, despite being on
> a machine with an 8Gig HD and 64M of ram....
> G Cook: Perhaps, but Notepad is still the most functional program
> in the whole suite!
-- --------------------------------------------------------- Victor Yodaiken FSMLabs: www.fsmlabs.com www.rtlinux.com FSMLabs is a servicemark and a service of VJY Associates L.L.C, New Mexico.
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