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Re: About priority of processes.
I use the word 'process' to describe the working memory context of an
application.
I use the word 'thread' to describe the execution contexts which actuall
run code in a process.
In Linux, each thread actuall obtains a unique thread id and process id,
whereas in other Unix implementations, each thread gets a unique thread
id, but share a common process id.
My understanding, which may be wrong, is that all non-realtime threads
share a common base level priority. Non-realtime threads never preempt
each other to obtain the runnable state for the CPU. Having said that,
I don't know what function "nice" performs on a thread (it is not
obvious looking at the kernel code). I suspect that it detracts from
the percentage of time the thread gets ron from the pool of time
allocated to non-realtime threads (?).
Realtime threads, can be run only as root, and their priority can be set
using the POSIX function shed_setparam. These threads preempt other
threads when their state becomes runnable. Take a look at man -k sched
to get a list of realtime scheduling functions.
Make sure that any realtime threads you create perform some sort of
blocking (they do not run continuously), or you will never see your
console I/O until the next reboot :)
Nat
On Sun, 2003-05-04 at 07:35, Jose Luis Alarcon wrote:
> Hi.
>
> Please, i wanna quest you how the priority of the
> processes is asigned.
>
> I am trying know the mechanism for asign the priority
> and who is the 'entity' that asign it. The developer of
> an aplication?, the developers of the kernel?, the cpu
> by itself?.
>
> Thanks you, very much, in advance.
>
> Regards.
>
> Jose.
>
>
> http://linuxespana.scripterz.org
>
> FreeBSD RELEASE 4.8.
> Mandrake Linux 9.0 Kernel 2.4.19 XFS.
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>
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