Re: [patch 0/4] perf_counter tools: support annotation of live kernel modules

Frederic Weisbecker
2009-07-03T08:41:23Z

On Fri, Jul 03, 2009 at 09:17:39AM +0200, Mike Galbraith wrote:
> On Thu, 2009-07-02 at 14:10 +0200, Peter Zijlstra wrote:
> > On Thu, 2009-07-02 at 09:17 +0200, Mike Galbraith wrote:
> >
> > > I've been pondering a perf archive tool
> > > that would package everything that's needed to do analysis on a
> > > different box. One big problem though, is that while you can easily
> > > package vmlinux and modules, what about all the userland binaries? A
> > > large perf.data and/or debug info binaries can easily make transport
> > > impractical enough.
> >
> > I would simply extend the current file header with another section in
> > which we do a structured storage of the data structures we currently
> > build in perf-report. That is, the dso and symbol bits.
> >
> > If we then run perf-report on a file containing such a section we read
> > that data instead of trying to locate them the regular way.
>
> That's a good idea.
>
> If uname doesn't match stored record time uname, you're not live, so
> tools require an exportable perf.data. If you're not live and not on
> the same host, annotate requires binaries appended via an export tool
> with --sym-filter -k -u -% whatever capability.
>
> -Mike

Also that would make easier the implementation of a perf compare thing.
A perf compare may have several uses, including:

(1) comparing different workloads with a same executable.
(2) comparing different executable versions for a same workload
(3) (1) + (2) ?

For the (2), having self contained record files as operands would let
comparisons based on symbols, pretty useful when you have to compare
two different vmlinux (or whatever binary executable).