From: Nathan Lynch <ntl@pobox.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: __cpu_up vs. start_secondary race?
Date: Tue, 2 Dec 2008 23:20:20 -0600 [thread overview]
Message-ID: <20081203052020.GG6829@localdomain> (raw)
In-Reply-To: <1228279963.7356.238.camel@pasglop>
Benjamin Herrenschmidt wrote:
> On Tue, 2008-12-02 at 20:16 -0600, Nathan Lynch wrote:
> > Apart from barriers (or lack thereof), the fact that __cpu_up gives up
> > after a more-or-less arbitrary period seems... well, arbitrary. If we
> > get to "Processor X is stuck" then something is seriously wrong:
> > there's either a kernel bug or a platform issue, and the CPU just
> > kicked is in an unknown state. Polling indefinitely seems safer, no?
> > Especially since some hypervisors allow overcommitting processors and
> > memory, which can introduce latencies in unexpected places.
>
> I'm pretty happy to keep the timeout :-) Proved useful in many cases
> where we actually fail to bring it up or crash it at bringup. From my
> experience, most of the time, the stuck CPU isn't getting in the way and
> it gets us a chance to move forward.
Fair enough -- thanks.
prev parent reply other threads:[~2008-12-03 5:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-01 21:30 __cpu_up vs. start_secondary race? Nathan Lynch
2008-12-01 22:08 ` Benjamin Herrenschmidt
2008-12-03 2:16 ` Nathan Lynch
2008-12-03 4:14 ` Trent Piepho
2008-12-03 4:52 ` Benjamin Herrenschmidt
2008-12-03 5:20 ` Nathan Lynch [this message]
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