From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: xenconsoled CPU denial of service problem Date: Wed, 04 Oct 2006 12:52:52 -0500 Message-ID: <4523F4F4.1090508@us.ibm.com> References: <20060829155900.GC970@redhat.com> <20060911141905.GB26811@redhat.com> <20061004135026.GC474@redhat.com> <4523E634.7050901@us.ibm.com> <20061004171939.GF474@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20061004171939.GF474@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Daniel P. Berrange" Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Daniel P. Berrange wrote: > On Wed, Oct 04, 2006 at 11:49:56AM -0500, Anthony Liguori 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. > Xenconsole could still spit out on a PTY. You don't necessarily need a daemon though (you could launch a xenconsole for each domain that was started). That also gives you a bit more choice in how you expose the console (you could have a xenconsole that spit out via TCP). Furthermore, we don't have to break guest compatibility. Older guests just have a very small buffer. It doesn't solve the event channel storming.. Maybe that's something to do in the hypervisor? Regards, Anthony Liguori > Dan. >