[ale] Linux vs XP Embedded

[Bjorn Dittmer-Roche]

On Tue, 24 Feb 2004, Bjorn Dittmer-Roche wrote:

> I'm no expert but I've done a bit of research on the topic. If you are not
> doing serious real-time, either OS should be fine as far as scheduling.
> You can expect simmilar performance and latency out of them and you'll
> have to actually do benchmarking to determine which performs better with
> the hardware in question. Linux is a joy to program and some people really
> like to program windows, too, so I would make that decision based on the
> experience/preferance of the admins/programmers and, ahem, the need for
> reliability.
>
> FreeBSD is another great option for high performance/small footprint/no
> charge. It's got great threading and very good latency and linux binary
> comatibility which, in amny cases, outperforms "real" Linux.
>
> If XP/Linux 2.6/FreeBSD won't cut it in the scheduling department, you
> need something more serious. You can't do better than QNX. QNX is really
> quite increadible. It's posix compliant, real-time, well supported and if
> you need to write your own drivers for anything, it will take much less
> time in QNX than anything else because the drivers run in protected
> memory space.
>
> The "real-time"  versions of linux don't use the same userland API's as
> normal processes, so I'm told that as a result they are difficult to
> program and have some annoying restrictions, so I would stay away from
> that.

Not that you asked about the other OSes, but sionce I've already mentioned
them I shouldn't leave out VxWorks, which now is planning some sort of
union with Linux:

http://www.linuxdevices.com/news/NS6013277917.html

>
> 	bjorn
>
> On Tue, 24 Feb 2004, Joe Knapka wrote:
>
> > Hi folks,
> >
> > I've been given an interesting realtime control system to build, and
> > my employer wants to evaluate both Linux (woohoo!) and Windows XP
> > Embedded (bummer).  I know some of you have some embedded/realtime
> > experience with Linux, so I'd like your opinions on this subject.  I
> > can't say much about the application itself, except that it will be
> > handling something in the neighborhood of 50Gbytes per day (that's a
> > G) of IP and serial traffic, and must meet hard deadlines on the order
> > of once per second (but a missed deadline won't kill anyone - this is
> > not a medical or aviation application. We can probably even recover
> > from a missed deadline, but that sort of thing should be kept to an
> > absolute minimum).
> >
> > I'm thinking that a 2.6-series kernel would be the way to go with
> > this.  I understand 2.6 integrates the preemptive and low-latency
> > patches, and that 2.6 can be built in a VM-less configuration so as to
> > remove latency associated with demand paging.
> >
> > Does anyone have any further suggestions or alternatives?  Also, is
> > anyone here in a position to evaluate the relative strengths of Linux
> > vs XP Embedded?  Personally I feel that the "Embedded" part of that
> > name is probably pure marketing hype, but I could be wrong.  It is hard
> > to see how Linux could possibly be a *worse* choice then XP in this
> > domain, though.
> >
> > Thanks,
> >
> > -- Joe Knapka
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> >
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