From owner-freebsd-arch  Tue Mar  5  4:26: 6 2002
Delivered-To: freebsd-arch@freebsd.org
Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16])
	by hub.freebsd.org (Postfix) with ESMTP
	id EC5B337B417; Tue,  5 Mar 2002 04:23:20 -0800 (PST)
Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102])
	by mailman.zeta.org.au (8.9.3/8.8.7) with ESMTP id XAA24088;
	Tue, 5 Mar 2002 23:23:19 +1100
Date: Tue, 5 Mar 2002 23:24:10 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
X-X-Sender:  <bde@gamplex.bde.org>
To: Poul-Henning Kamp <phk@FreeBSD.ORG>
Cc: <arch@FreeBSD.ORG>
Subject: Re: kernel process priority question...
In-Reply-To: <17280.1015281145@critter.freebsd.dk>
Message-ID: <20020305223033.M4715-100000@gamplex.bde.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-freebsd-arch@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-arch.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-arch>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-arch>
X-Loop: FreeBSD.ORG

On Mon, 4 Mar 2002, Poul-Henning Kamp wrote:

> What is the correct way to set a priority on a kernel thread ?
>
> Is it legal to simply set the value like this:
>
>         curthread->td_base_pri = PRIBIO;
>
> Or should the detour around the rtprio stuff be used:
>
>         struct rtprio rtp;
>
>         rtp.prio = RTP_PRIO_MAX;
>         rtp.type = RTP_PRIO_IDLE;
>         mtx_lock_spin(&sched_lock);
>         rtp_to_pri(&rtp, td->td_ksegrp);
>         mtx_unlock_spin(&sched_lock);

Neither.

The rtprio stuff should be just compatibility cruft to support the
rtprio(2) mistake (extending {get,set}priority(2) would have been a
smaller mistake, but even these were obsoleted by the POSIX.1-1993
about a year before rtprio(2) was committed).

When setting priority fields directly, there are 4 of them in places
that keep being moved by KSE changes, and the setting may need locking,
so a function to hide the details would be useful.  rtp_to_prio() is
not that function.

Bruce


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-arch" in the body of the message