Neutrino Question

QNX Newsgroups (Archives) qdn.public.qnxrtp.newuser
1

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

2

There is no ‘scheduler process’. Microkernel does scheduling since it gets
hardware interrupts from timer.

  • igor

“Sudhakar Tadi” <stadi@npd.hcltech.com> wrote in message
news:a5f65m$aia$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

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

3

Sudhakar Tadi <stadi@npd.hcltech.com> wrote:

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

There is no scheduler process – though there is a scheduler section
to the kernel.

Essentially, the kernel is enterred on every interrupt, trap or fault
(e.g. integer divide by 0) and every kernel call. Before the kernel
“returns” to an application, it has to decide which application to
return to, this is when scheduling is done – the decision of which
application to return to.

There is no process, running in a loop, deciding “now I’ll schedule
thread A, now I’ll schedule thread B”.

-David

QNX Training Services
http://www.qnx.com/support/training/
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