When is this RT Linux orgasim going to end?

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ed1k

Re: When is this RT Linux orgasim going to end?

Post by ed1k » Wed Oct 30, 2002 8:46 pm

"Kevin Stallard" <kevin@ffflyingrobots.com> wrote in message
news:apong7$6dc$1@inn.qnx.com...
Realtime doesn't mean "real-fast" and it can apply to a lot more than just
device control. Douglas Jensen has some interesting things to say on the
subject. See http://www.real-time.org/preview/introduction.htm
Thanks Kevin for the yet another interesting link. I never heard name
Douglas Jensen, but I agree with his point. Also I've read some articles
about real-time at QSSL website. I remember one of them was really
scientific like... and probably real-time for me it's something what's
called hard real-time. Ok. Where I said "real-fast"? For example, take a
look at Dedicated System's report QNX vs WinCE... and, for example, at such
important parameter as interrupt latency. What do you see? WinCE _sometimes_
in ten times slower than QNX. So, you're yelloing it's not real-time, it's
not predictable... It's true for equal boards. Then take the board ten times
faster with WinCE. What do you see? It's mainly faster then you need, but
worst case is good for you. In many cases, you have limited time to do a
task, but you don't care if task is calculated faster. Mostly important for
real-time is the maximal time which you need to spend for calculation in
order to not be flooded by input data stream. And second important parameter
for real-time is the delay between input data and well calculated output
data, because the data might be not actual (expired data). So, real-time is
not "real-fast". It's "real-predictable_fast"... IMHO.
Also, I know about excellent system architecture of QNX, about lots of
problems concerning all another OS... It's not a start of such discussion, I
hope.

Thanks everybody,
Eduard.
Kevin

"ed1k" <ed1k@nobody.fools.ca> wrote in message
news:apnrhg$691$1@inn.qnx.com...
"Kevin Stallard" <kevin@ffflyingrobots.com> wrote in message
news:apnjiq$rir$1@inn.qnx.com...
Hmmm...how did I miss that....they are talking about embedded linux,
nothing
about real-time there....

Thanks Kevin. Very interesting picture. Funny to compare next/current
ratio
for different OSes... FreeBSD is a leader and QNX isn't last one :) And
real-time... what's real-time now? nobody care of real-time because
there
are lots of cheap and fast CPU now... but embedded it's still
something...

Cheers,
Eduard.




ed1k

Re: When is this RT Linux orgasim going to end?

Post by ed1k » Wed Oct 30, 2002 8:54 pm

"Dmitri Ivanov" <ivdal@yahoo.com> wrote in message
news:apomn4$5jl$1@inn.qnx.com...
Thanks Kevin. Very interesting picture. Funny to compare next/current
ratio
for different OSes... FreeBSD is a leader and QNX isn't last one :) And
real-time... what's real-time now? nobody care of real-time because
there
are lots of cheap and fast CPU now... but embedded it's still
something...

What's embedded then?
I guess it's some tools like mkifs... maybe, some support of specific
hardware... eh.. something like touch-screen... Or in other words, something
like LEGO.
Memories are chip, flash disks has IDE interface,
CPUs are fast - why not put Windows NT inside your stereo? ;)
Right now I have no computer... I have no even stereo... But good idea!
Excellent! I will try to put NT inside of my old "Zenit" camera :)

Eduard.
____
No dark sarcasm in the class-room (c)

Kevin Stallard

Re: When is this RT Linux orgasim going to end?

Post by Kevin Stallard » Wed Oct 30, 2002 9:19 pm

It doesn't matter that CE is ten times slow...as long as it is (as you say)
predictable.

There are definitely other considerations as well...but as you say, I don't
want to get involved with such a discussion either. The point I was making
was that some will attempt to crank up the CPU so they will meet their
deadlines using bad scheduling algorithms or because of some other weakness
in the OS they are using...and I thought that was what you meant.

Somehow...I find myself, once again, having incorrectly assumed ;)

Best Regards,
Kevin



Regards,
Kevin
"ed1k" <ed1k@nobody.fools.ca> wrote in message
news:appg8g$4r7$1@inn.qnx.com...
"Kevin Stallard" <kevin@ffflyingrobots.com> wrote in message
news:apong7$6dc$1@inn.qnx.com...
Realtime doesn't mean "real-fast" and it can apply to a lot more than
just
device control. Douglas Jensen has some interesting things to say on
the
subject. See http://www.real-time.org/preview/introduction.htm

Thanks Kevin for the yet another interesting link. I never heard name
Douglas Jensen, but I agree with his point. Also I've read some articles
about real-time at QSSL website. I remember one of them was really
scientific like... and probably real-time for me it's something what's
called hard real-time. Ok. Where I said "real-fast"? For example, take a
look at Dedicated System's report QNX vs WinCE... and, for example, at
such
important parameter as interrupt latency. What do you see? WinCE
_sometimes_
in ten times slower than QNX. So, you're yelloing it's not real-time, it's
not predictable... It's true for equal boards. Then take the board ten
times
faster with WinCE. What do you see? It's mainly faster then you need, but
worst case is good for you. In many cases, you have limited time to do a
task, but you don't care if task is calculated faster. Mostly important
for
real-time is the maximal time which you need to spend for calculation in
order to not be flooded by input data stream. And second important
parameter
for real-time is the delay between input data and well calculated output
data, because the data might be not actual (expired data). So, real-time
is
not "real-fast". It's "real-predictable_fast"... IMHO.
Also, I know about excellent system architecture of QNX, about lots of
problems concerning all another OS... It's not a start of such discussion,
I
hope.

Thanks everybody,
Eduard.


Kevin

"ed1k" <ed1k@nobody.fools.ca> wrote in message
news:apnrhg$691$1@inn.qnx.com...
"Kevin Stallard" <kevin@ffflyingrobots.com> wrote in message
news:apnjiq$rir$1@inn.qnx.com...
Hmmm...how did I miss that....they are talking about embedded linux,
nothing
about real-time there....

Thanks Kevin. Very interesting picture. Funny to compare next/current
ratio
for different OSes... FreeBSD is a leader and QNX isn't last one :)
And
real-time... what's real-time now? nobody care of real-time because
there
are lots of cheap and fast CPU now... but embedded it's still
something...

Cheers,
Eduard.






ed1k

Re: When is this RT Linux orgasim going to end?

Post by ed1k » Wed Oct 30, 2002 10:31 pm

"Kevin Stallard" <kevin@ffflyingrobots.com> wrote in message
news:appi1p$6sa$1@inn.qnx.com...
It doesn't matter that CE is ten times slow...as long as it is (as you
say)
predictable.

There are definitely other considerations as well...but as you say, I
don't
want to get involved with such a discussion either. The point I was
making
was that some will attempt to crank up the CPU so they will meet their
deadlines using bad scheduling algorithms or because of some other
weakness
in the OS they are using...and I thought that was what you meant.
Yes, you're right. Just now I'm looking for a job in Toronto and it's very
funny nobody know QNX here. Maybe, I visited wrong places... I got feeling
the QNX is more popular in Ukraine LOL! They're telling/writting here about
mission critical, real-time and Linux... best case I heard VxWorks :)

Cheers,
Eduard.
___
JAZZ has a sense of Humor (c)
Somehow...I find myself, once again, having incorrectly assumed ;)

Best Regards,
Kevin

Mario Charest

Re: When is this RT Linux orgasim going to end?

Post by Mario Charest » Thu Oct 31, 2002 2:23 am

"Bill Caroselli (Q-TPS)" <QTPS@EarthLink.net> wrote in message
news:appa9f$rp7$1@inn.qnx.com...
Does "these" include QNX. We used QNX4 very successfully.
Yes "these" includes QNX. The fact that you use it doesn't change that I
wouldn't ;-)

- Mario

ed1k

Re: When is this RT Linux orgasim going to end?

Post by ed1k » Thu Oct 31, 2002 5:46 am

"Kevin Stallard" <kevin@ffflyingrobots.com> wrote in message
news:apni88$q9i$1@inn.qnx.com...
This is your brain.

This is your brain on RT linux.
I forgot to mention discussion at russian community forum concerning the
matter:

http://qnx.org.ru/forum/viewtopic.php?t ... show_all=1

I'm afraid many people will need some translator, because this discussion is
in Russian...

Maybe, this one allows you to catch the idea:

http://www.translate.ru/eng/srvurl.asp

Don't forget to select Russian-English translation :)

P.S. I tried that translator myself, it's just a big fun :oD But this is
better translator I know :(
Best regards,
Eduard.
I didn't use pictures because they would be too graphic.

The number of people thinking about using RT linux in their next projects
is
much higher than I would have expected. The problems with it are so
obvious
that it is a wonder why people aren't running from it.

The people who use RT linux successfully must be really good engineers, my
hat is off to them...but why use it? I don't get it....

This link was on OS news as of today (Tuesday October 29th, 2002)

http://www.windowsfordevices.com./artic ... 35685.html


Kevin



Akhilesh Mritunjai

Re: When is this RT Linux orgasim going to end?

Post by Akhilesh Mritunjai » Thu Oct 31, 2002 6:57 am

"ed1k" <ed1k@nobody.fools.ca> wrote in message news:appgo0$5d2
Right now I have no computer... I have no even stereo... But good idea!
Excellent! I will try to put NT inside of my old "Zenit" camera :)
WOW!! Me got an old broken zenit too. I should try too. Or how about making
the first toaster running QNX :-)

Rennie Allen

Re: When is this RT Linux orgasim going to end?

Post by Rennie Allen » Thu Oct 31, 2002 7:30 am

Mario Charest wrote:
"Bill Caroselli (Q-TPS)" <QTPS@EarthLink.net> wrote in message
news:appa9f$rp7$1@inn.qnx.com...

Does "these" include QNX. We used QNX4 very successfully.


Yes "these" includes QNX. The fact that you use it doesn't change that I
wouldn't ;-)
Care to elaborate why you wouldn't ? Gaming machines are
not exactly rocket science. I use QNX on much more challenging
applications...

Rennie

Mario Charest

Re: When is this RT Linux orgasim going to end?

Post by Mario Charest » Thu Oct 31, 2002 3:04 pm

"Rennie Allen" <rallen@csical.com> wrote in message
news:3DC0DC0A.6070501@csical.com...
Mario Charest wrote:
"Bill Caroselli (Q-TPS)" <QTPS@EarthLink.net> wrote in message
news:appa9f$rp7$1@inn.qnx.com...

Does "these" include QNX. We used QNX4 very successfully.


Yes "these" includes QNX. The fact that you use it doesn't change that
I
wouldn't ;-)

Care to elaborate why you wouldn't ?
Not really.
Gaming machines are not exactly rocket science.
I use QNX on much more challenging applications...


Rennie

Steve Cobb

Re: When is this RT Linux orgasim going to end?

Post by Steve Cobb » Fri Dec 20, 2002 5:44 pm

Care to elaborate why you wouldn't ?

Not really.
Oh come on Mario.... Please. :-)

I assume that we are talking the mall sort of video game machines. Is that
what you are thinking?

I am really curious as to your reasoning. I'm thinking that for gaming,
it's the development tools and familiarity is the key thing. Thus using a
Windows version and the associated grapics environment 2D and 3D is going to
be hard to beat.

Besides, "hard real-time" is not at all critical. Even "soft real-time" is
pushing it - yes you want fast response times, but we are talking on the
order of 100 to 200 ms or so. That is the limit of human perception.

Besides, you can't then "port" it to a CD and sell it mass market.

Mario, do you have other issues also?

Steve

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