Neutrino Question

Hi All,

I am just going through the Neutrino Micro kernel, In that the text
specifies,

“Unlike threads, Neutrino itself never scheduled for execution. The
processor executes code in the kernel only as the result of a thread’s
making an explicit kernel call or in response to a hardware interrupt”.

I have one question about this

“How would it be possible for us to state that microkernel is
non-schedulable in QNX when the scheduling process is running as part of the
microkernel”.

Please clarify

Thanks in Advance
-Tadi

Sudhakar Tadi
HCL Technologies,Chennai, INDIA.
ph: 91-44-3741939-42 ex:2312
Fax:91-44-3741038
http://san.hcltech.com

“Sudhakar Tadi” <stadi@npd.hcltech.com> wrote in
news:a5f6k2$arv$1@inn.qnx.com:

Hi All,

I am just going through the Neutrino Micro kernel, In that the text
specifies,

“Unlike threads, Neutrino itself never scheduled for execution. The
processor executes code in the kernel only as the result of a thread’s
making an explicit kernel call or in response to a hardware interrupt”.

I have one question about this

“How would it be possible for us to state that microkernel is
non-schedulable in QNX when the scheduling process is running as part
of the microkernel”.

Please clarify

This idea is that Neutrino is a passive device - it will never schedule
itself to run on its own accord. Someone must make a request (via
syscall), or an interrupt occurs (or exception).

\

Cheers,
Adam

QNX Software Systems Ltd.
[ amallory@qnx.com ]

With a PC, I always felt limited by the software available.
On Unix, I am limited only by my knowledge.
–Peter J. Schoenster <pschon@baste.magibox.net>

Sudhakar Tadi wrote:

“How would it be possible for us to state that microkernel is
non-schedulable in QNX when the scheduling process is running as part of the
microkernel”.

Please clarify

The scheduler is a state machine. Since it is purely reactive (and there
is no other software entity which determines when it can react) it is
never scheduled. This is true of every scheduler that I am aware of,
and is in no way unique to the QNX scheduler.

Of course a hardware engineer might suggest that the scheduler is
scheduled by the hardware (the schedule being the timer interrupt), but
no self-respecting s/w engineer would pay any attention to such heresy :wink: