Messages in this thread | | | Date | Wed, 20 Nov 2013 07:09:38 -0700 | From | David Ahern <> | Subject | Re: [PATCH] perf script: Print callchains and symbols if they exist - v2 |
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On 11/20/13, 6:04 AM, Frederic Weisbecker wrote:
> We probably want to avoid DSO and IP for most tracepoints. For kernel > tracepoints dso is going to be the kernel anyway and IP is often not that relevant > either.
Sorry, you mentioned that last time and I forgot to respond.
Yes, there are a number of tracepoints that are completely kernel side and possibly uninteresting callstacks. There are others that are triggered in process context and you want to see the stacks all the way back to main. I would hope that users are adding -g to record only when it is truly wanted. Given that the idea of perf-script is to print data in a file why not dump everything in the file - address, dso, and symbol. There is always -G to suppress the callchains.
As an example it is useful to see the overhead of 'perf sched record -g': all I really want is callchains on sched_switch, and the callchains on sched_stat_runtime and wakeup are huge emphasizing the need to specify events where callchains are interesting and not collect them on others and that steps into the pandora's box of mixed sample types.
David
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