Date: Mon, 07 Jul 2003 15:34:02 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: deischen@freebsd.org Cc: threads@freebsd.org Subject: Re: libc_r silliness Message-ID: <XFMail.20030707153402.jhb@FreeBSD.org> In-Reply-To: <Pine.GSO.4.10.10307071444090.4037-100000@pcnet5.pcnet.com>
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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).
> 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}?
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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