Re: How does the windows specific aspects of nice work?

[Igor Pechtchanski <pechtcha at cs dot nyu dot edu>]

On Tue, 30 Sep 2003, Jason House wrote:

> I did a search online and found the following message (but no reply to
> it).  Does anyone know the particulars about nice?  If it still works as
> they describe (with 2 non-normal priorities), does anyone know when it
> will allow the full range of window supported priorities?
>
>      * From: "Thomas Chadwick" <j_tetazoo at hotmail dot com>
>      * To: cygwin at cygwin dot com
>      * Date: Mon, 06 Jan 2003 14:44:37 -0500
>      * Subject: nice command?
>      * Bcc:
>
> I got to playing around with Windows 2000 Task Manager the other day and
> discovered that you can change the priority of a running task. This led
> me to discover that you can specify the priority of a task when you
> launch it by way of the windows start command using one of the following
> options:
>
> LOW Start application in the IDLE priority class
> NORMAL Start application in the NORMAL priority class
> HIGH Start application in the HIGH priority class
> REALTIME Start application in the REALTIME priority class
> ABOVENORMAL Start application in the ABOVENORMAL priority class
> BELOWNORMAL Start application in the BELOWNORMAL priority class
> WAIT Start application and wait for it to terminate
>
> I then got to playing with nice (under Cygwin) to see what I could do
> about setting the priority of a Cygwin task. I used the following syntax
> and tried a number of values of x:
>
> nice -n x programname.exe
>
> I found that specify a value of x=0 results in NORMAL priority. For any
> value of x > 0, I found I got a priority of LOW. For any value of x < 0,
> I found I got a priority of HIGH.
>
> I tried "man nice" and "info nice" and got scant documentation. I'm just
> curious if this is the expected behavior of nice? Is my analysis
> correct, or are there other values of "x" that will get me the other
> Windows priorities? FWIW, there's a Cygwin task I'd like to launch with
> AboveNormal priority.

I suspect it's a <http://cygwin.com/acronyms/#PTC> situation...  The
implementation of the "nice()" syscall simply doesn't know about the
AboveNormal priority value (see winsup/cygwin/syscalls.cc:2512).  There is
a more fine-grained control mechanism in the "sched_setparam()" Cygwin API
call, but the "nice" program doesn't use it.
	Igor
P.S. Another thing that's missing is a "renice" program.  Also PTC.
-- 
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