Date: Fri, 13 Jun 2008 18:54:14 +0300
From: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: tzanussi@gmail.com, akpm@linux-foundation.org, compudj@krystal.dyndns.org,
       linux-kernel@vger.kernel.org, righi.andrea@gmail.com
Subject: Re: [PATCH 3/3] relay: Add buffer-only channels; useful for early
 logging.
Message-ID: <20080613185414.306b4baa@linux360.ro>
In-Reply-To: <48521C19.6070001@cs.helsinki.fi>
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	<48521C19.6070001@cs.helsinki.fi>
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On Fri, 13 Jun 2008 10:04:57 +0300
Pekka Enberg <penberg@cs.helsinki.fi> wrote:

> Why do we need to change for_each_online_cpu to for_each_present_cpu?
> I guess it's because we don't have all the CPUs online at early
> boot?

Yes, that's true. Only one CPU is online at that early point.

> Wouldn't it then be better to implement CPU hotplug support
> instead?

It's difficult for me to write such code, as I'm unable to test CPU
hotplug; my machines are a Turion X2 laptop and a Athlon Barton desktop
computer. So I can't turn off, or unplug in a software sense, one CPU core.
Correct me if I'm wrong, but I don't see any way to do that in /sys/devices/system/cpu/

But I suppose I could write a patch very carefully, and then submit to
someone that can test this. Anyway, I'll look into this and try to
understand the code without being able to test.


	Eduard
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