Montavista's "Open Source Real-Time Linux Project" again
tglx at linutronix.de
Fri Oct 15 10:20:43 CEST 2004
On Fri, 2004-10-15 at 02:18, Karim Yaghmour wrote:
> Thomas Gleixner wrote:
> > Yeah, I know. I doubt that.
> You doubt which part of what I said?
".. want to go ahead and show that it is deterministic, they can."
Show ? With a scope ?
> > Provide a static codepath analysis for all execution paths and I might
> > buy your arguments.
> Right, and then you have the nerve to lecture me about self-adulation ...
> I don't have the time to do this myself, but I'd really love to plug a
> scope and a function generator to machine and compare the VP patches and
> RTAI under very high stress. This certainly would certainly be food for
> thought for everyone involved.
And the scope does what you argued in a LKML thread and what I asked for
"And this has been demonstrated mathematically/algorithmically to be
true 100% of the time, regardless of the load and the driver set?"
That's why I was saying "blah". Provide the things yourself to prove
your point, before asking others to provide them.
Here are the LibeRTOS/KURT (2.4) numbers on the same machine (300MHZ
Pentium) compared to RTAI in a long run test:
IRQ latency for a self contained IRQ
No Load 7,8 usec 7,8 usec
ping -f 8,6 usec 9,8 usec
hackbench 12,6 usec 11,8 usec
hbench + ping-f 13,6 usec 13,4 usec
RTAI LXRT LibeRTOS
No Load 18,92 usec 20,45 usec
ping -f 19,10 usec 21,14 usec
hackbench 33,10 usec 35,16 usec
hackb + ping -f 34,56 usec 35,40 usec
I don't claim to have a static codepath analysis for that, but those
numbers certainly arent food for your arguments.
Maybe they are food for objective thoughts about different approaches
and their (dis)advantages.
More information about the Rtai