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Re: Re: [Xen-devel] Question regarding xentrace


  • To: André Bögelsack <Andre.Boegelsack@xxxxxxxxx>
  • From: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
  • Date: Mon, 7 Jun 2010 15:29:23 +0100
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Dulloor <dulloor@xxxxxxxxx>
  • Delivery-date: Mon, 07 Jun 2010 07:30:15 -0700
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Hmm, that would be rather exceptional... the trace_id's haven't really changed since tracing was introduced, only new ones added.  Are you sure you're using the xentrace_format that matches up to the 3.2 hypervisor you're using (and not, say, something from -unstable)?  The format changed from fixed-length records to variable-length records somewhere around there (can't remember exactly).

If you take a really short trace (i.e., just let it run for 5 seconds before interrupting), I can try to take a quick look at it, to see what I see.

 -George

On Mon, Jun 7, 2010 at 2:50 PM, André Bögelsack <Andre.Boegelsack@xxxxxxxxx> wrote:
I didn't change anything so I assume it is the same version across the tools.

These are the events I gathered from xentrace:


It is not possible to call a HVM event on that hardware platform - the CPU is too old.

My guess is, that the trace_id's recorded by xentrace and interpreted by xentrace_format are not identical. Is there any way to prove it?

Regards
André

Dulloor <dulloor@xxxxxxxxx> schrieb am 03.06.2010 22:02:02:

> Von: Dulloor <dulloor@xxxxxxxxx>

> An: André Bögelsack <Andre.Boegelsack@xxxxxxxxx>
> Kopie: xen-devel@xxxxxxxxxxxxxxxxxxx
> Datum: 03.06.2010 22:02
> Betreff: Re: [Xen-devel] Question regarding xentrace
>
> Are you using xentrace_format, xentrace, and xen all from the same
> version ? I don't think the trace-ids are incompatible across
> versions, but still.
> Also, what HVM events are you seeing ?
>
> -dulloor
>
> On Mon, May 17, 2010 at 11:58 PM, André Bögelsack
> <Andre.Boegelsack@xxxxxxxxx> wrote:
> > Hi,
> >
> > I've made some SAP benchmarks on my Xen system and discovered a huge
> > difference in the performance of a "xened" SAP system compared to a native
> > SAP system. Hence, I tried to figure out what might cause this 'overhead'
> > and run a xentrace (listining to all events). Xentrace produced 24gb data
> > and I converted it to 27gb human-readable data by using xentrace_format.
> > After I gathered the human-readable data, I filtered the data and counted
> > the appearance of each event. So far, so good.
> >
> > Now it comes: although I used paravirt-guests, the xentrace-tool reported
> > HVM events in the trace data. Moreover, from my point of view it is
> > impossible to trace HVM events, as I use AMD Opteron 280 with no AMD-V
> > feature.
> >
> > Did I miss something or does the xentrace-tool report 'wrong' trace data?
> >
> > I use Xen version 3.2.0_16718_14-0.4 (from Suse).
> >
> > Thanks
> > André
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> >
http://lists.xensource.com/xen-devel
> >
> >

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