From: Jamie Lokier <lk@tantalophile.demon.co.uk>
To: Adrian Cox <adrian@humboldt.co.uk>
Cc: george anzinger <george@mvista.com>,
Rik van Riel <riel@conectiva.com.br>,
Boris Dragovic <lynx@falcon.etf.bg.ac.yu>,
Oswald Buddenhagen <ob6@inf.tu-dresden.de>,
linux-kernel@vger.kernel.org
Subject: Re: static scheduling - SCHED_IDLE?
Date: Mon, 12 Mar 2001 19:05:27 +0100 [thread overview]
Message-ID: <20010312190527.A23065@pcep-jamie.cern.ch> (raw)
In-Reply-To: <Pine.LNX.4.33.0103081747010.1314-100000@duckman.distro.conectiva> <3AA93124.EC22CC8A@mvista.com> <3AA93ABE.7000707@humboldt.co.uk>
In-Reply-To: <3AA93ABE.7000707@humboldt.co.uk>; from adrian@humboldt.co.uk on Fri, Mar 09, 2001 at 08:19:10PM +0000
Adrian Cox wrote:
> Unfortunately the kernel is already full of counting semaphores.
> Priority inheritance won't save you, as the task which is going to call
> up() need not be the same one that called down().
>
> Jamie Lokier's suggestion of raising priority when in the kernel doesn't
> help. You need to raise the priority of the task which is currently in
> userspace and will call up() next time it enters the kernel. You don't
> know which task that is.
Dear oh dear. I was under the impression that kernel semaphores are
supposed to be used as mutexes only -- there are other mechanisms for
signalling between processes.
Do any processes ever enter userspace holding a critical semaphore?
(Things like userspace signalling another userspace don't count -- it's
your own fault and your own problem if _that_ deadlocks).
-- Jamie
next prev parent reply other threads:[~2001-03-12 18:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-03-07 17:40 Oswald Buddenhagen
2001-03-07 18:04 ` Rik van Riel
2001-03-07 19:20 ` Oswald Buddenhagen
2001-03-07 21:34 ` ludovic
2001-03-08 11:17 ` Zdenek Kabelac
2001-03-08 11:41 ` Andrew Morton
2001-03-08 13:29 ` Boris Dragovic
2001-03-08 13:44 ` Rik van Riel
2001-03-08 20:19 ` Boris Dragovic
2001-03-08 20:47 ` Rik van Riel
2001-03-09 19:38 ` george anzinger
2001-03-09 20:19 ` Adrian Cox
2001-03-12 18:05 ` Jamie Lokier [this message]
2001-03-12 19:37 ` Adrian Cox
2001-03-13 9:40 ` Jamie Lokier
2001-03-10 2:58 ` Rik van Riel
2001-03-09 19:42 ` Jamie Lokier
2001-03-10 3:02 ` Rik van Riel
2001-03-09 20:09 ` Jamie Lokier
2001-03-10 4:56 ` Rik van Riel
2001-03-14 13:19 ` Jamie Lokier
2001-03-15 3:13 ` Rik van Riel
2001-03-14 14:26 ` Philipp Rumpf
2001-03-09 11:26 ` Pavel Machek
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