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[Xen-devel] Re: xenconsoled CPU denial of service problem

To: "Daniel P. Berrange" <berrange@xxxxxxxxxx>, Anthony Liguori <aliguori@xxxxxxxxxx>
Subject: [Xen-devel] Re: xenconsoled CPU denial of service problem
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Wed, 04 Oct 2006 18:42:55 +0100
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On 4/10/06 18:19, "Daniel P. Berrange" <berrange@xxxxxxxxxx> wrote:

>> Considering that today in Xen we have a default buffer size, it seems
>> considerably easier to me to just get rid of xenconsoled completely and
>> expand the domU-kernel ring queue to be the actual size of what we're
>> buffering today.
>> 
>> This eliminates all of these problems and gets rid of a dom0 daemon.
>> Plus, the domU gets taxed for the buffer memory instead of dom0.
>> 
>> We would then change xenconsole to read the buffer directly.
> 
> Its very useful to be able to expose the data as a Psuedo-TTY, as
> it lets people use standard toolset for dealing the DomU log data.
> eg virt-manager can just connect up a VTE terminal widget straight
> to the TTY for a terminal UI. Or tools like ttywatch can log the
> data to file, or network, etc. Or minicom for a standard text based
> interactive client, etc Forcing everything to use the custom
> xenconsole client program would be a step backward.

There's also the issue of backward compatibility with guests with a small
inter-domain ring. And this doesn't solve the fundamental problem of dom0
getting slammed with lots of event-channel notification. We need rate
limiting anyhow, on all our inter-domain comms channels.

 -- Keir



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