From: Daniel Phillips <phillips@bonn-fries.net>
To: yodaiken@fsmlabs.com, Daniel Phillips <phillips@bonn-fries.net>
Cc: yodaiken@fsmlabs.com, Robert Love <rml@tech9.net>,
Mikael Pettersson <mikpe@csd.uu.se>,
linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: 2.4.18 Preempt Freezeups
Date: Sun, 17 Mar 2002 02:14:14 +0100 [thread overview]
Message-ID: <E16mPFW-0000mo-00@starship> (raw)
In-Reply-To: <3C9153A7.292C320@ianduggan.net> <E16mObg-0000mZ-00@starship> <20020316181338.A26242@hq.fsmlabs.com>
In-Reply-To: <20020316181338.A26242@hq.fsmlabs.com>
On March 17, 2002 02:13 am, yodaiken@fsmlabs.com wrote:
> On Sun, Mar 17, 2002 at 01:33:04AM +0100, Daniel Phillips wrote:
> > On March 16, 2002 01:40 am, yodaiken@fsmlabs.com wrote:
> > >
> > > Without preempt:
> > > x = movefrom processor register;
> // if preemption is on, we can be preempted and restart
> // on another processor so x will be wrong
> > > do_something with x
> > >
> > > is safe in SMP
> > > With [preempt] it requires a lock.
> >
> > It must be a trick question. Why would it?
>
> See comment.
Which processor register were you thinking of? Surely not anything in the
general register set, and otherwise, it's just another example of per-cpu
data. It needs to be protected, and the protection is lightweight.
--
Daniel
next prev parent reply other threads:[~2002-03-17 1:21 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-15 1:51 2.4.18 Preempt Freezeups Ian Duggan
2002-03-15 1:54 ` Robert Love
2002-03-15 8:36 ` Ian Duggan
2002-03-15 14:25 ` Robert Love
2002-03-15 16:11 ` Mikael Pettersson
2002-03-15 19:11 ` Robert Love
2002-03-16 0:40 ` yodaiken
2002-03-16 1:46 ` Mike Fedyk
2002-03-16 3:12 ` yodaiken
2002-03-17 0:33 ` Daniel Phillips
2002-03-17 1:13 ` yodaiken
2002-03-17 1:14 ` Daniel Phillips [this message]
2002-03-17 1:54 ` yodaiken
2002-03-17 2:08 ` Daniel Phillips
2002-03-17 21:17 ` Davide Libenzi
2002-03-15 14:30 ` Alan Cox
2002-03-15 21:36 ` Ian Duggan
2002-03-15 2:11 ` Alan Cox
2002-03-15 8:38 ` Ian Duggan
2002-03-15 8:51 ` David S. Miller
2002-03-15 14:28 ` Alan Cox
2002-03-16 23:51 ` Daniel Phillips
2002-03-17 3:31 ` Alan Cox
2002-03-17 12:59 ` Dave Jones
2002-03-15 8:43 ` Daniel Phillips
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