The OS Tech forum might be the better choice of forums, but that's fine...

Neutrino only uses a single timer tick interrupt, regardless of the number of CPUs, and it is typically bound to CPU 0 
so you won't get any jitter from timer interrupts on other cores.  The board startup is responsible for determining 
where interrupts get directed, so you have control over where interrupts get handled -- you can direct them all to CPU 0
.  The only exception is IPIs -- inter-processor interrupts -- which we must have.  Typically they are only relevant for
 scheduling events, but if your processes are all bound to other CPUs, that won't be a concern either.

Doug

-----Original Message-----
From: David Snowdon [mailto:community-noreply@qnx.com]
Sent: Mon 15/03/2010 21:04
To: general-community
Subject: Neutrino Timer ticks
 
Hello all, 

I'm presently evaluating QNX for use in some high-end financial systems. In particular, I'm interested in multiprocessor
 support, which QNX seems to support well (unlike other microkernel-based RTOSes). In particular I'm interested in a BMP
-style system to provide latency guarantees on polled system events.

I can't see any reference as to whether, on these BMP-style systems, it is possible to disable the system timer tick, 
and any other interrupts for bound CPUs, in order to remove the possibility of jitter thanks to those interrupts. I 
assume that something with QNX's real-time heritage supports this type of configuration, but the documentation seems to 
suggest that clock ticks are required to maintain the system's internal timers. 

If this is not the appropriate forum, could someone please point me in the right direction?

Regards, 

David Snowdon
Senior Hardware and Software Engineer
Zomojo Pty Ltd. 



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General
http://community.qnx.com/sf/go/post49559