Hello my name is Javier Melendez, I am Peruvian and I am studying in the UPC
(Peruvian University of applicates sciences). I am finding the answers about
any questions of QNX like system operation. The questions are the
followings:
1.- The priority range from 0 to 31 is only in positive?
2.- Well, if the range is positive. How are the diference about the system
operative process and the user process?
3.- Wich cases are applicable the algorithm Round Robin and wich adaptative
planification?
4. - If arrive a process and doesnt enought memory available… what up?
its possible any routine of swap? whats up about the process?
thank you about your answers…
and
Very truly yours…
Javier Melendez
Javier Melendez <javier@barreda.com.pe> wrote:
1.- The priority range from 0 to 31 is only in positive?
Is only positive. Also, really the usable priority range is
1-29. idle runs at 0, and you don’t want to compete with idle for
CPU; only Proc32 can run at 30; and 31 is a “true” priority, but is
sometimes used to show the nominal priority of hardware interrupt handlers.
(That is, it isn’t an ordinary scheduling priority, but on a different
continuum.)
2.- Well, if the range is positive. How are the diference about the system
operative process and the user process?
Processes started by non-superuser ids can not set their priority above
19.
3.- Wich cases are applicable the algorithm Round Robin and wich adaptative
planification?
Round-robin and FIFO affect how processes at the same priority behave.
Adaptive is about the same as RR, except that if the process uses a
complete time-slice without blocking, its priority will drop one level.
(This decay will happen only one level from the original, not multiple
times.) Whether any particular case happens depends on the scheduling
algorithm assigned to the process in question.
-
- If arrive a process and doesnt enought memory available… what up?
its possible any routine of swap? whats up about the process?
No swapping exists. Messages are NOT queued in the QNX system. If
a message is sent, the smaller of the specified send size and receive
size will be copied. There are library routines available to copy more
data from the sender to the receiver. (see ReadMsg().)
-David
QNX Training Services
dagibbs@qnx.com