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[Xen-devel] Re: events/0 and xenconsoled wakeups

To: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: events/0 and xenconsoled wakeups
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Thu, 31 Mar 2011 10:34:08 -0700
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On 03/31/2011 05:19 AM, Sander Eikelenboom wrote:
> Hello Jeremy,
> Tuesday, March 29, 2011, 11:14:04 PM, you wrote:
>> On 03/25/2011 03:28 PM, Sander Eikelenboom wrote:
>>> Hi Jeremy,
>>> Is this thing still on your list ?
>>> http://www.gossamer-threads.com/lists/linux/kernel/1281515
>>> Ran powertop today, and events/0 and xenconsoled seem to be still 
>>> responsible for the majority of wakeups.
>> Yeah.  Unfortunately the underlying bug is a design error in the tty
>> subsystem, which will be hard to fix.  However, the one-liner fix can
>> mitigate the problem and reduce the wakeups to 100Hz.
>> Also, attaching a console to the various hvcs will also fix it.
> Consoles of guests ?
> Could you give a example of how to do it ?

Just running "xl console <domid>" will drain the pending console output,
and stop all the wakeups.  I think you can get xenconsoled to log into a
file (or /dev/null) which will also fix it.  The wakeups come from
having unconsumed console output from the guest sitting in the pty buffer.


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