linux-kernel - Re: Fwd: Kernel Power management ?? turning off used devices that are in use.

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Date:	Mon, 7 Nov 2011 17:04:58 +0000
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	hagar <hagar@...et.net.au>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Joel Schopp <jschopp@...tin.ibm.com>,
	Ashok Raj <ashok.raj@...el.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: Fwd: Kernel Power management ?? turning off used devices that
 are in use.

On Fri, Nov 04, 2011 at 02:56:25PM +0800, hagar wrote:
> 
> I have traced this behaviour to the cpu hotplug code.
> 
> I need to be able to either switch off cpu hotpluging - or at least
> prevent hotplugging certain cpu's

The kernel doesn't automatically hotplug CPUs on idle. Something in your 
userspace is doing so. I think that Ubuntu's powernap will do so under 
certain circumstances - try disabling that if you have it.

(Which doesn't alter the fact that there appears to be a bug here)

-- 
Matthew Garrett | mjg59@...f.ucam.org
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