From: Tejun Heo <tj@kernel.org>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
tigran@aivazian.fsnet.co.uk, tglx@linutronix.de, mingo@elte.hu,
hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org,
Linux PM mailing list <linux-pm@lists.linux-foundation.org>
Subject: Re: [BUGFIX][PATCH] Freezer, CPU hotplug, x86 Microcode: Fix task freezing failures
Date: Sun, 2 Oct 2011 17:40:51 -0700 [thread overview]
Message-ID: <20111003004051.GD31799@mtj.dyndns.org> (raw)
In-Reply-To: <4E88C3D4.2020300@linux.vnet.ibm.com>
Hello,
On Mon, Oct 03, 2011 at 01:34:36AM +0530, Srivatsa S. Bhat wrote:
> So when a CPU goes offline and comes back online, I don't see why the kernel
> should not reuse the microcode that it already has. Anyhow the microcode will
> not change. The same microcode would be requested from userspace again if the
> kernel has freed its copy.
Can't one take a cpu offline, hot unplug it from the board and put in
a new one and then bring it online? That's usually what "hot
[un]plug" stands for. I don't think one would be able to put in a
very different processor but maybe, say, revision difference is
allowed and microcode should be looked up again? Assuming that the
same microcode can always be applied after the actual CPU is swapped
could be dangerous. Again, I'm not sure about how this is supposed to
be managed so I could be wrong.
If I'm not wrong, can't we add synchronization between cpu hotplug and
freezer so that they don't happen in parallel?
Thanks.
--
tejun
next prev parent reply other threads:[~2011-10-03 0:40 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-02 19:05 Srivatsa S. Bhat
2011-10-02 19:36 ` Rafael J. Wysocki
2011-10-02 19:50 ` Tejun Heo
2011-10-02 20:04 ` Srivatsa S. Bhat
2011-10-03 0:40 ` Tejun Heo [this message]
2011-10-03 5:51 ` Srivatsa S. Bhat
2011-10-03 8:47 ` Borislav Petkov
2011-10-04 7:15 ` Tejun Heo
2011-10-04 13:15 ` Srivatsa S. Bhat
2011-10-04 13:46 ` Borislav Petkov
2011-10-04 17:14 ` Borislav Petkov
2011-10-04 19:49 ` Rafael J. Wysocki
2011-10-04 20:57 ` Srivatsa S. Bhat
2011-10-05 7:21 ` Borislav Petkov
2011-10-05 8:51 ` Srivatsa S. Bhat
2011-10-05 20:26 ` Rafael J. Wysocki
2011-10-05 21:15 ` Srivatsa S. Bhat
2011-10-05 22:43 ` Rafael J. Wysocki
2011-10-06 6:50 ` Srivatsa S. Bhat
2011-10-06 8:34 ` Borislav Petkov
2011-10-06 15:47 ` Srivatsa S. Bhat
2011-10-06 18:11 ` Srivatsa S. Bhat
2011-10-06 20:35 ` [BUGFIX][PATCH RESEND] " Srivatsa S. Bhat
2011-10-06 22:13 ` Tejun Heo
2011-10-06 22:34 ` Borislav Petkov
2011-10-07 16:48 ` Srivatsa S. Bhat
2011-10-07 18:05 ` Borislav Petkov
2011-10-04 13:25 ` [BUGFIX][PATCH] " Borislav Petkov
2011-10-05 8:33 ` Srivatsa S. Bhat
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