freebsd stable - Jan 2010 - About nice(1), renice(8) and ULE scheduler

HI all,

I've realized that the nice(1) code hasn't been modified for a long time
(last code change seems from 4 years ago according the sources).

?Is the nice(1) behaviour the expected? I mean, ?Has been the ULE 
scheduler adapted to nice(1) command or not?

nice(1) is a very old command based on old concepts and created in times 
when SMP didn't exist. So ?it works correctly when a modern an 
re-designed scheduler as ULE is used?

Maybe I have to read again this paper:
http://www.usenix.org/event/bsdcon03/tech/full_papers/roberson/roberson.pdf

-- 
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brings total obliteration. I will face my fear. I will permit it to pass 
over me and through me. And when it has gone past I will turn the inner 
eye to see its path. Where the fear has gone there will be nothing. Only 
I will remain.

Bene Gesserit Litany Against Fear.

Jordi Espasa Clofent <jespasac@minibofh.org> wrote:
 > I've realized that the nice(1) code hasn't been modified for a
long time
 > (last code change seems from 4 years ago according the sources).
 > 
 > ?Is the nice(1) behaviour the expected? I mean, ?Has been the ULE 
 > scheduler adapted to nice(1) command or not?
 > 
 > nice(1) is a very old command based on old concepts and created in times 
 > when SMP didn't exist. So ?it works correctly when a modern an 
 > re-designed scheduler as ULE is used?

In fact nice is a very simple program.  It only changes the
priority value of a process in a POSIX-compliant way.
There is no need to change or adapt it; it still works fine
in the SMP world and with new schedulers.  It's up to the
scheduler to interpret and handle the priority values of
processes.

In other words:  The nice(1) tool only attaches a number to
a process, nothing more.  Only the scheduler knows what that
number means.  So there's no need to change nice(1).

By the way, the source code of nice(1) is almost trivial.
Basically it just calls the setpriority(2) and execve(2)
syscalls.  99% of the source file consists of the BSD
license test, arguments parsing and C syntax overhead.

Best regards
   Oliver

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