Re: [Xen-devel] [PATCH 0/3] continuable destroy domain:MakeXEN_DOMCTL_destroydomain hypercall continuable

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

Xend probably has a critical resource (either a lock or a thread) that gets tied up in the shutdown. So it can’t do anything else significant while the shutdown is in progress. The solution will be to add some multi-threading (perhaps just as simple as spawning a thread to handle long operations like domain destruction or coredumps). Someone already posted a (rather complicated) patch to spawn a thread to deal with domain coredumps. It hasn’t been checked in as there were arguments over the approach (it spawned an external C program, whereas it should be quite possible to spawn the thread and do the coredump without any exec of an external program).

Thus this is something of a current design limitation of xend rather than an outright bug. As such it  is unlikely to get fixed anytime soon unless someone wants to pick it up as a project?

 -- Keir

On 9/10/07 16:49, "Szymanski, Lukasz K" <Lukasz.Szymanski@xxxxxxxxxx> wrote:

> If I do not use xm top while the vm is shutting down, there are fewer or no problem with system responsiveness.  
> - If I run xm list (or xm info or xm dmesg) during a shutdown, then nothing gets listed, but I have control over all the terminals and I can ctrl-C my way out of the xm command.  
> - If I do a shutdown and a non xm command such as ping, I can ping another domain and I have no responsive problems at all with zero packets lost.
>  
> It appears that the error is in the combination of xm commands and shutdown.  Running xm top with shutdown shows this behavior the most.
>  
> At this point I am trying to find out exactly when things get stuck for xm top and shutdown.




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