Re: [Xen-users] How to detect a domain shutdown with as less overheadas possible?

[Kip Macy <kip.macy@xxxxxxxxx>]

> to reap in the crashed path. I guess if you're *really* lazy, you can
> have xend send /var/tmp/myscript.pid a signal whenever it reaps a
> domain. Although I doubt a patch for this would be accepted :-)

Hmm, it might actually make sense for applications to be able to
register with xend for asynchronous notification of various classes of
events. Although the hack I suggested probably shouldn't go in,
something like it might be desirable.

                                                              -Kip







> 
>                                              -Kip
> 
> On 4/29/05, Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx> wrote:
> > > I've just finished a simple Perl script that brings out a
> > > whole domain from a directory (with a small config file and
> > > some <device>.gz files), create Logical Volumes with each
> > > device, starts the domain, wait for the domain to shutdown,
> > > push back into the *.gz the content of the LVs and remove
> > > them. This is quite handy to launch any test machine stored
> > > on the NFS server on one of our Xenified hosts.
> >
> > Nice.
> >
> > > My problem is the overhead of checking for the domain to shut
> > > down as I intend to use the domUs not only for functional
> > > testing but also to have a good guess of the performance we
> > > can get on real hardware (with only one domU / real host).
> >
> > We should introduce a call-out for domain exits. Kip's looking core
> > dumps, so I guess he's addressing this.
> >
> > > After xm create, this script regularly calls :
> > > xm domid "domainname"
> > > The problem is that this check eats a small chunk of CPU
> > > time: it takes
> > > 0.2 - 0.3s of real CPU time on each call. I've looked into
> > > /proc/xen hoping to find the list of domains stored here,
> > > allowing a simple file read or stat to give me the
> > > information I need, but it seems there's nothing like this.
> >
> > There's a bunch of improvements to xend waiting to be posted which will
> > likely help. There's certainly no good reason to be using CPU unless you
> > have console output active or something.
> > Ian
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> >
>

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