From: Ralf Baechle <ralf@oss.sgi.com>
To: Machida Hiroyuki <machida@sm.sony.co.jp>
Cc: kevink@mips.com, aj@suse.de, hjl@lucon.org, linux-mips@oss.sgi.com
Subject: Re: patches for test-and-set without ll/sc (Re: thread-ready ABIs)
Date: Thu, 24 Jan 2002 10:59:15 -0800 [thread overview]
Message-ID: <20020124105915.A838@dea.linux-mips.net> (raw)
In-Reply-To: <20020123145634M.machida@sm.sony.co.jp>; from machida@sm.sony.co.jp on Wed, Jan 23, 2002 at 02:56:34PM +0900
On Wed, Jan 23, 2002 at 02:56:34PM +0900, Machida Hiroyuki wrote:
> > It should in principle be SMP safe.
>
> I don't think so.
>
> Suppose that
> THREAD A is bound to CPU A and THREAD B is bound to CPU B.
> THREAD A and THREAD B are running on_atomic_inc_nollsc().
> Two threads are really running at the same time, without
> context-switch. In this case nobody clear k1.
There is a method for mutual exclusion called Dekker's Algorithem (sp?)
which only requires just atomic stores and can be implemented in plain
C. Downside is it's weak performance that renders it pretty much a CS
only thing.
Ralf
next prev parent reply other threads:[~2002-01-25 1:49 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-22 14:25 patches for test-and-set without ll/sc (Re: thread-ready ABIs) Machida Hiroyuki
2002-01-22 17:16 ` Kevin D. Kissell
2002-01-22 17:16 ` Kevin D. Kissell
2002-01-22 18:08 ` Jason Gunthorpe
2002-01-22 18:19 ` Kevin D. Kissell
2002-01-22 18:19 ` Kevin D. Kissell
2002-01-23 5:56 ` Machida Hiroyuki
2002-01-23 8:38 ` Kevin D. Kissell
2002-01-23 8:38 ` Kevin D. Kissell
2002-01-24 18:59 ` Ralf Baechle [this message]
2002-01-25 4:39 ` Machida Hiroyuki
2002-01-25 7:25 ` Kevin D. Kissell
2002-01-25 7:25 ` Kevin D. Kissell
-- strict thread matches above, loose matches on Subject: below --
2002-01-20 10:38 thread-ready ABIs Machida Hiroyuki
2002-01-20 11:58 ` Kevin D. Kissell
2002-01-20 13:16 ` Machida Hiroyuki
2002-01-22 6:27 ` patches for test-and-set without ll/sc (Re: thread-ready ABIs) Machida Hiroyuki
2002-01-22 6:37 ` Ulrich Drepper
2002-01-22 6:46 ` Machida Hiroyuki
2002-01-22 6:56 ` Ulrich Drepper
2002-01-24 9:56 ` Andreas Jaeger
2002-01-24 9:56 ` Andreas Jaeger
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