From: "Russ Cox" <rsc@swtch.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Re: [sources] 20070413: /rc/bin/cpurc.local
Date: Tue, 17 Apr 2007 01:21:16 -0400 [thread overview]
Message-ID: <20070417052050.13DC11E8C3A@holo.morphisms.net> (raw)
In-Reply-To: <9ab217670704151334k121fbbffp426cd8c379848bad@mail.gmail.com>
> Not to be overly annoying, but _is_ it possible that between the
> assignment and that test, p->mach is set, indicating another CPU took
> over? It just doesn't seem like m->readied is locked, at all; it seems
> like another CPU could pick it up in the middle.
Many things are possible. m->readied is just a hint.
p->mach is just a hint unless you hold the scheduling lock.
That's why dequeueproc double-checks:
All the accesses in the if condition are just fine --
they happen without a lock but dequeueproc double-checks
that p is okay to schedule.
Russ
prev parent reply other threads:[~2007-04-17 5:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <f93786a38200d44b7406b3181b4e2c20@cat-v.org>
2007-04-15 8:06 ` Uriel
2007-04-15 17:00 ` Uriel
2007-04-15 17:26 ` Devon H. O'Dell
2007-04-15 17:35 ` erik quanstrom
2007-04-15 17:37 ` Devon H. O'Dell
2007-04-15 17:38 ` Russ Cox
2007-04-15 17:43 ` Uriel
2007-04-15 20:31 ` Devon H. O'Dell
2007-04-15 17:43 ` Devon H. O'Dell
2007-04-15 17:59 ` Russ Cox
2007-04-15 20:34 ` Devon H. O'Dell
2007-04-17 5:21 ` Russ Cox [this message]
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