Javier Melendez <javier@barreda.com.pe> wrote:
Hello, please could your respond me this answers?
What version of QNX are you running? The exact answer to many of
these questions will vary between QNX4 & QNX6.
- Unix manipulates negative priority for owners process of their operating
system. The Questions is: QNX only manipulates positives priorities?. What
is the range for this kind of process?.
My understanding is that priorities on most Unixes are positive only,
though they are mostly a relative matter.
Still, QNX only handles positive priority values, the range is 0-30 for
QNX4 and 0-63 for QNX6, with some restrictions. Under QNX4, priority 30
is only available for the process manager, under QNX6, priority 0 is
only available for idle. Also, there is a maximum value that a
non-superuser (not root, not uid 0) process can set for its priority, and
that value is 19 under QNX4, and I think also 19 under QNX6.
- QNX, Manners 3 methods: FIFO, Round-Robin and Adaptitive Planification.
If arrives a process, wich are the method selected?. I Can select the method
to work?
From this question, it would suggest you are asking about QNX4.
Each process has a scheduling algorithm (method) assigned to it – it is
part of the process table entry. The System Architecture manual has a
good description of how scheduling works and is probably the best place
to look. If a process wants to change its scheduling algorithm, it can
call sched_setscheduler(), though this is normally inherited from its
parent. It can also be changed from the command line with the slay utility.
Scheduling algorithm is only important if more than one process is READY
at the same priority.
- If arrive a process and doesnt enought memory? whats up?
This situation never happend? why?
Depends – if you try to run/create a process and there isn’t a enough
memory, the process creation will fail. If a process tries to allocate
more memory and there isn’t enough memory available, the allocation routine
will fail. What happens after that depends on how carefully the process was
coded.
- What is the Quantity of memory to work with QNX?
Depends on what you want to do. A small, single purpose embedded QNX4
system could run with 1M of memory. If you’re looking for a desktop
development oriented QNX4 system, 64M is plenty. If you’re looking at
small development systems, not going to be running a browser with a lot
of cache, minimal GUI, then 32M is probably ok.
-David
QNX Training Services
I do not answer technical questions by email.