1 : As we would liketo use QNX RTP at next real time control project,
anyone knows Lynx 3.1 reputation that is other microkernel OS.
2 : How is QNX RTP sys call overhead?
Usually Microkernel sys call overhead much bigger than monolithic
kernel.
3 : Anyone know QNX RTP kernel size?
As QNX 4.1 was 10K, maybe QNX RTP is 35K?
Shinichi Shinozuka <shino@onr.com> wrote:
1 : As we would liketo use QNX RTP at next real time control project,
anyone knows Lynx 3.1 reputation that is other microkernel OS.
2 : How is QNX RTP sys call overhead?
Usually Microkernel sys call overhead much bigger than monolithic
kernel.
Depends on what you mean by a system call. In general, the set of calls
that would be classified as a system-call under QNX are much smaller
then under say BSD. What is normally more important is the overall
system overhead (function calls, system calls, context switch time). In
most tests that matter I have found QNX to be much lighter weight then
monolithics. However, you are going to be able to find situations on both
types of systems that exploit their weaknesses.
Can you be more specific in what kind(s) of overhead (or performance)
issues you are concerned about?
3 : Anyone know QNX RTP kernel size?
As QNX 4.1 was 10K, maybe QNX RTP is 35K?
Depends on what you mean as “the kernel”. Technically the QNX4
kernel was about 10k but the smallest functioning unit the outside
would could use was Proc32 and it is about 131k. On QNX6 the
smallest functioning unit is procnto and from my PatchC RTP machine
it is about 210k. However, the QNX6 kernel+proc also provides a
lot more functionality in terms of threading, scheduling, synchronization,
and other features. Unfortunately these come at a small cost in size.
chris
\
cdm@qnx.com > “The faster I go, the behinder I get.”
Chris McKillop – Lewis Carroll –
Software Engineer, QSSL
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