Date: Mon, 7 Jul 2003 15:49:34 -0400 (EDT) From: Daniel Eischen <eischen@vigrid.com> To: John Baldwin <jhb@FreeBSD.org> Cc: threads@FreeBSD.org Subject: Re: libc_r silliness Message-ID: <Pine.GSO.4.10.10307071543570.15065-100000@pcnet5.pcnet.com> In-Reply-To: <XFMail.20030707153402.jhb@FreeBSD.org>
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On Mon, 7 Jul 2003, John Baldwin wrote:
>
> On 07-Jul-2003 Daniel Eischen wrote:
> > On Mon, 7 Jul 2003, John Baldwin wrote:
> >
> >> Just wondering why the PTHREAD_{MIN,MAX}_PRIORITY macros referenced in
> >> the pthread_{get,set}schedparam() man pages are not available to
> >> applications but are hidden in pthread_private.h. It would seem that
> >> these values should be exported in pthread.h.
> >
> > Because they are not defined by the POSIX spec. According
> > to POSIX you should use:
> >
> > sched_get_priority_max(), sched_get_priority_min()
> >
> > but it is confusing because these are specified for the process
> > scheduling. The values returned by these system calls, do not
> > necessarily correspond to the values used by our thread libraries
> > (in fact, they don't).
>
> They do if you use SCHED_RR (which is the default policy) or SCHED_FIFO.
> SCHED_OTHER uses -20 to 20 (nice values).
And SCHED_OTHER is where the confusion lies. In our thread
libraries (except libthr), SCHED_OTHER is treated the same
as SCHED_RR (priorites 0 .. 31). This no matchy kernel.
If you try to use those values in pthread_attr_setschedparam()
or pthread_setschedparam(), you would get EINVAL for values
less than 0.
> > I believe somewhere in the old spec, there were supposed to be
> > at least 31 or 32 priorities (I can't seem to find that mentioned
> > in the new spec). Our thread libraries, at least libc_r and
> > libpthread, use priorities 0 .. 31.
> >
> > I don't really know how to handle this. We can wrap
> > sched_get_priority_{min,max}(), but how do we know whether
> > the application wants process priorities or thread
> > priorities?
>
> Ugh. Perhaps the manpage should at least be updated to not
> reference the macros. What does POSIX say about the confusion
> between sched_get_priority_{min,max}?
Sure, update the man pages if you want ;-)
I have not found anything yet regarding sched_get_priority_{min,max}
confusion in the POSIX spec...
--
Dan Eischen
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