From: Philippe Anel <xigh@bouyapop.org>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] 9vx, kproc and *double sleep*
Date: Sat, 12 Jun 2010 09:02:51 +0200 [thread overview]
Message-ID: <4C13311B.4050704@bouyapop.org> (raw)
In-Reply-To: <f398e344c84e5946e0189ebb69638d57@kw.quanstro.net>
Hi,
I really think the spin model is good. And in fact, I really think
current sleep/wakeup/postnote code is good. However, this model makes
the assumption that plan9 processes are really Machs and not coroutines.
I think we need a larger model, which includes the scheduler.
I mean a model that describes a set of processes (in spin meaning),
picking one kind of coroutine objects from a run queue (shared by all
spin processes) and then calling sleep/wakeup/postnote a few times
before putting the coroutine object back to the run queue. These spin
processes would represent the cpus (or Machs) while coroutine objects
would represent the plan9 processes.
I even think we don't have to simulate the fact these processes can be
interrupted.
Again, the change I proposed is not about sleep/wakeup/postnote, but
because wakeup() is ready()'ing the awakened process while the mach on
which sleep() runs is still holdind a pointer (up) to the awakened
process and can later (in schedinit()) assumes it is safe to access
(up)->state. Because of this, schedinit() can tries to call ready() on
(up), because because (up)->state may have been changed to Running by
a third mach entity.
This change only updates schedinit() (and tries) to make (up)->state
access safe when it happens after a sleep() is awakened.
Phil;
>
> in any event, given the long history with sleep/wakeup, changes should
> be justified with a promula model. the current model omits the spl*
> and the second lock. (http://swtch.com/spin/sleep_wakeup.txt).
>
> - erik
>
>
next prev parent reply other threads:[~2010-06-12 7:02 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-11 14:06 Philippe Anel
2010-06-11 14:40 ` ron minnich
2010-06-11 14:49 ` erik quanstrom
2010-06-11 14:54 ` Philippe Anel
2010-06-11 15:03 ` erik quanstrom
2010-06-11 15:22 ` Philippe Anel
2010-06-11 15:25 ` Philippe Anel
2010-06-11 14:59 ` Philippe Anel
2010-06-11 17:11 ` Bakul Shah
2010-06-11 17:31 ` Philippe Anel
2010-06-11 18:34 ` Bakul Shah
2010-06-11 18:36 ` erik quanstrom
2010-06-11 18:51 ` Philippe Anel
2010-06-12 7:02 ` Philippe Anel [this message]
2010-06-12 9:22 ` Philippe Anel
2010-06-12 11:51 ` erik quanstrom
2010-06-13 13:01 ` Richard Miller
2010-06-13 13:43 ` Philippe Anel
2010-06-13 14:26 ` Philippe Anel
2010-06-13 16:20 ` ron minnich
2010-06-13 16:34 ` Philippe Anel
2010-06-13 17:23 ` Philippe Anel
2010-06-13 18:03 ` Philippe Anel
2010-06-14 19:15 ` Charles Forsyth
2010-06-14 19:36 ` Philippe Anel
2010-06-15 2:57 ` ron minnich
2010-06-15 3:36 ` ron minnich
2010-06-12 20:15 ` Richard Miller
2010-06-12 20:30 ` ron minnich
2010-06-12 22:15 ` Charles Forsyth
2010-06-13 0:04 ` ron minnich
2010-06-13 13:32 ` erik quanstrom
2010-06-13 22:34 ` Charles Forsyth
2010-06-13 9:00 ` Richard Miller
2010-06-11 14:49 ` Philippe Anel
2010-06-11 14:59 ` ron minnich
2010-06-11 15:02 ` ron minnich
2010-06-11 15:04 ` erik quanstrom
2010-06-11 15:43 ` ron minnich
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