Re: xpc target ERROR: CPU OVERLOADED AT TIME
- From: "Arnaud Miege" <arnaud.miege@xxxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 30 Jun 2009 16:35:52 +0100
"Gilles" <gb@xxxxxxxxxxxxxxxxxx> wrote in message
news:h2davu$4e3$1@xxxxxxxxxxxxxxxxxxxxx
Hello dear xPCtargeters,
Like some other users, i have an ERROR: CPU OVERLOADED AT TIME... during
my xPCtarget execution, but this one has never appeared before at lower
sampling rates.
Here's the configuration of the host :
MATLAB Version 7.5
(R2007b)
Simulink Version 7.0
(R2007b)
Control System Toolbox Version 8.0.1
(R2007b)
Filter Design Toolbox Version 4.2
(R2007b)
Fixed-Point Toolbox Version 2.1
(R2007b)
Real-Time Workshop Version 7.0
(R2007b)
Real-Time Workshop Embedded Coder Version 5.0
(R2007b)
Signal Processing Toolbox Version 6.8
(R2007b)
Simulink Fixed Point Version 5.5
(R2007b)
xPC Target Version 3.3
To minimize tcp ip network latency between target and host computers, i
connect the target directly to a second ethernet card in a dedicated
subnet limited to these 2 computers. I can disconnect the host from the
local network if required with the first host Ethernet card disabled. This
isolation from the rest of the network does not change anything in the
error behavior.
The target is equipped with a PCI6024 DAQ and its Ethernet card.
The model includes just one ADC and DAC operations, no other processing,
these io are grounded, no scope, nothing else, really.
The "xpcbench this " test gives the following informations:
1- minimal achievable samples times
minimal=16us, F14=20us, F14*5=67us, F14*10=42uS, F14*25=93us;
2- relative performance = 0.7.
The installed C compiler is the Open Watcom C/C++/FORTRAN Version 1.3.
With sampling frequencies below 10 kHz, the execution runs normally.
Above, i get the annoying error message ERROR: CPU OVERLOADED AT TIME on
the target's sceen for an average Task Execution Time shown time that
never exeeds 10us.
Today, i really need to speed up the sampling frequency to 30-50kHz range
for a fast servo control application.
Any ideas ?
Best regards, Gilles.
The average TET only gives you an indication, for the actual TET try:
plot(tg.TimeLog,tg.TETLog)
Also, have you got Legacy USB enabled in the BIOS of the target computer?
This creates system interrupts which really hamper the performance of the
real-time environment. You should be able to see this if you have regular
spikes in the TETLog. I would suggest disabling any legacy USB in the BIOS.
Finally, the Microsoft compiler (professional edition if you can afford it)
can give better performance than the Watcom, especially if you turn
optimizations on. Unfortunately, it's not free like the Watcom one.
HTH,
Arnaud
Arnaud
.
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- From: Gilles
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