Re: [Xen-users] Does xen support Intel Processor Trace?

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Sep 20, 2017 at 12:08:11AM -0400, Zihan Yang wrote:
> > >* I'd like to use Intel PT to analyze xen crashes, but I don't find the*
> >
> > I'm not sure Intel PT is useful to analyze Xen crashes. If Xen crashes
> > the whole system goes down, so how are you going to fetch the trace
> > data then?
> It seems that Xen has already ported the kdump mechanism(in
> http://www-archive.xenproject.org/files/summit_3/kexec_kdump.pdf).
> So I guess it might be possible to coredump xen when it crashes, altough I 
> have
> not tried it myself. According to your experience, is it a practical solution?

In my experience the best way to debug Xen crashes is to use the
serial console and add debug messages when necessary.

> > It could be interesting for performance analysis IMHO.
> 
> I agree, but pure instruction flow seems not sufficient to detect accurate
> reason of performance downgrade(e.g. The growth of response delay). I
> think some
> extra manual checks are needed.

I'm not sure what you mean with "The growth of response delay", but in
any case I guess Intel PT could be useful for performance analysis if
someone spends the time to port it to Xen.

Roger.

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