From owner-svn-src-head@FreeBSD.ORG  Thu Jan  6 21:42:43 2011
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Date: Thu, 6 Jan 2011 21:42:43 +0000
From: Alexander Best <arundel@freebsd.org>
To: John Baldwin <jhb@freebsd.org>
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Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
	src-committers@freebsd.org, Konstantin Belousov <kib@freebsd.org>,
	Garrett Cooper <gcooper@freebsd.org>
Subject: Re: svn commit: r216955 - head/usr.sbin/rtprio
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On Thu Jan  6 11, John Baldwin wrote:
> On Thursday, January 06, 2011 4:10:17 pm Alexander Best wrote:
> > On Thu Jan  6 11, Garrett Cooper wrote:
> > > On Thu, Jan 6, 2011 at 12:41 PM, Alexander Best <arundel@freebsd.org> 
> wrote:
> > > 
> > > ...
> > > 
> > > > this causes problems when pid is -0:
> > > >
> > > > [id|rt]prio -t -0 and [id|rt]prio 10 -0 will try to run "0" via 
> execvp().
> > > > beforehand however this will also trigger rtprio().
> > > >
> > > > a better solution would be to do:
> > > >
> > > >                if (argv[2][0] == '-') {
> > > >                        proc = parseint(argv[2] + 1, "pid");
> > > >                        if (rtprio(RTP_SET, proc, &rtp) != 0)
> > > >                                err(1, "RTP_SET");
> > > >                } else {
> > > >                        execvp(argv[2], &argv[2]);
> > > >                                err(1, "%s", argv[2]);
> > > >                }
> > > 
> > > How did you get a pid of -0?
> > 
> > pid 0 stands for the current process. see rptio(2).
> 
> Note that that usage is rather pointless since it means you apply rtprio to 
> the 'rtprio' process that is about to exit. :)

yeah but at least it makes the usage of -X consistent. ;) also consider the
following: the current shell has idle priority and you want to run rtprio in
normal priority. then rtprio -t -0 would be a neat way of doing
rtprio -t rtprio. ;) wel...not quite, because the priotity gets set to "NORMAL"
when rtprio is almost finished running. ;)

i admit using -0 for setting rtpio's own priority isn't very useful, but the
rtprio(1) manual states:

Pid of 0 means "the current process".

...so it better work. ;)

cheers.
alex

> 
> -- 
> John Baldwin

-- 
a13x