Messages in this thread | | | Date | Wed, 6 Apr 2011 14:15:07 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH -tip v3 3/6] perf branch trace: print pid and command |
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On Fri, Apr 01, 2011 at 11:11:10AM -0600, David Ahern wrote: > > > On 04/01/11 09:13, Frederic Weisbecker wrote: > > On Mon, Mar 28, 2011 at 08:31:23AM -0600, David Ahern wrote: > >> On 03/28/11 04:34, Akihiro Nagai wrote: > >>>> from is sample->ip? to is sample->addr? In the above example > >>>> 0x39d3015260 is the value from sample->addr, 1526f is sample->ip which > >>>> resolves to _dl_next_ld_env_entry from /lib64/ld-2.13.so. > >>> Yes. > >>> In this example, resolved address is only sample->ip (branch from). > >>> We need the resolved address of sample->addr (branch to) too, because > >>> both of them are addresses of execution code. > >> > >> Ok, now I understand. In that case add conversion of sample->addr to > >> symbols to perf-script. > > > > I agree that we should rather use perf script for branch dumps. > > Sorry Akihiro, I think we suggested you to create this dedicated > > perf branch by the past. But then perf script became the vanilla dump > > tool in the middle and it seems more suitable today. > > > > We can still create a perf branch later in order to produce some more > > advanced post-processing tools. But for sample dumps perf script (which starts > > to show itself as a misnomer BTW) seems to be the right place. > > perf-dump?
Yeah. We could make it an alias of perf-script.
> > > > So, in this context, if we have PERF_SAMPLE_ADDR, we are going to always > > follow the ip with a "=>" and then resolve the address, etc... > > > > Yeah it makes sense for this default mode. But what about when we'll want > > a function graph kind of output? This will require a totally different > > layout. Also PERF_SAMPLE_ADDR may be used for different context in the > > future. > > > > Perhaps we want a kind of per evsel callback that makes its own > > interpretation of the pid/tid/dso/sym/etc... options asked by the > > user? > > The print addr function can take the evsel as an input. It includes the > event type which can be used to decide what the address means.
Also yeah. But once we'll have the graph output, that may become a real mess.
> > > > > But well, we can start simple and make and just do the => trick > > if we have PERF_SAMPLE_ADDR and resolve addr if the user asked > > the sym. Then when we have the graph output, have these per evsel > > display callbacks. > > There is another email thread about page faults. The user wants sample > address resolved to symbols. I was going to look into it next week when > I get back from vacation.
What we seem to need for that is to bring a pagefault tracepoint. We had propositions for that in the past, but work on this is in pause mode it seems.
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