We are designing a time critical system where we plan to use
QNX fine ISR latency charactersitics. I’s a lot of computations,
so we need PentiumIII class processors. I read about SMI/SMM
which seems to increase the worst case (ISR) latencies to 1ms
instead of the wanted 1us!
We plan to use the Embedded PIII/Celeron 400MHz processors.
Is it possible to disable the real-time killing SMI/SMM calls with
this processor? Is it perhaps BIOS dependent?
Is it impossible to get good realtime performance with modern x86 processors?
/ Tom
I believe it BIOS dependent. If your system needs the
features of SMI/SMM it effectively negates the any
real time aspect features of your OS or application.
Once initiated, it can’t be turned off. I’ve never
heard of an Intel PIII with this feature, but that
may be my ignorance.
Previously, Tomas Högström wrote in comp.os.qnx:
We are designing a time critical system where we plan to use
QNX fine ISR latency charactersitics. I’s a lot of computations,
so we need PentiumIII class processors. I read about SMI/SMM
which seems to increase the worst case (ISR) latencies to 1ms
instead of the wanted 1us!
We plan to use the Embedded PIII/Celeron 400MHz processors.
Is it possible to disable the real-time killing SMI/SMM calls with
this processor? Is it perhaps BIOS dependent?
Is it impossible to get good realtime performance with modern x86 processors?
/ Tom
–
Mitchell Schoenbrun --------- maschoen@pobox.com
Ok, sounds good. Does anybody know exatcly which products
to avoid because of this reason?
/ Tom
Mitchell Schoenbrun wrote:
I believe it BIOS dependent. If your system needs the
features of SMI/SMM it effectively negates the any
real time aspect features of your OS or application.
Once initiated, it can’t be turned off. I’ve never
heard of an Intel PIII with this feature, but that
may be my ignorance.
Previously, Tomas Högström wrote in comp.os.qnx:
We are designing a time critical system where we plan to use
QNX fine ISR latency charactersitics. I’s a lot of computations,
so we need PentiumIII class processors. I read about SMI/SMM
which seems to increase the worst case (ISR) latencies to 1ms
instead of the wanted 1us!
We plan to use the Embedded PIII/Celeron 400MHz processors.
Is it possible to disable the real-time killing SMI/SMM calls with
this processor? Is it perhaps BIOS dependent?
Is it impossible to get good realtime performance with modern x86 processors?
/ Tom
\
Mitchell Schoenbrun --------- > maschoen@pobox.com