Messages in this thread | | | Date | Wed, 21 Dec 2016 14:24:52 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info |
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On Wed, Dec 21, 2016 at 06:39:01PM +0530, Hari Bathini wrote: > Hi Peter,
> >I don't see how the tool can parse old records (with NAMESPACES_MAX == > >7) if you set its NAMESPACES_MAX to say 10. > > > >Then it will expect the link_info array to be 10 entries and either read > >past the end of the record (if !sample_all) or try and interpret > >sample_id as link_info records. > > > > Right. There will be inconsistency with data the perf tool tries to read > beyond > what the kernel supports. IIUC, you mean, include nr_namespaces field in the > record and warn the user if it doesn't match with the one perf-tool supports > before proceeding..?
Yes, if you add a nr_namespaces field its always parsable. If an old tool finds more namespace than it has 'names' for it can always display the raw index number. If a new tool finds the array short, it will not display the missing ones.
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