linux-kernel - Re: [PATCH 11/16] perf intel-pt: Add support for synthesizing callchains for regular events

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Message-ID: <5b8f28f5-968f-bfff-68af-ed0350a90765@intel.com>
Date:   Fri, 17 Apr 2020 16:50:00 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 11/16] perf intel-pt: Add support for synthesizing
 callchains for regular events

On 16/04/20 6:14 pm, Arnaldo Carvalho de Melo wrote:
> Em Wed, Apr 01, 2020 at 01:16:08PM +0300, Adrian Hunter escreveu:
>> Currently, callchains can be synthesized only for synthesized events.
>> Support also synthesizing callchains for regular events.
> 
> This is super cool, I wonder if we shouldn't do it automatically or just
> adding a new type of callchains, i.e.:
> 
> 	perf record --call-graph pt uname
> 
> Should take care of all the details, i.e. do the extra steps below
> behind the scenes.
> 
> Possibly even find out that the workload specified was built with
> -fomit-frame-pointers, that the hardware has Intel PT and do all behind
> the scenes for:
> 
> 	perf record -g uname
> 
> Alternatively we could take some less seemingly far fetched approach and
> make this configurable via:
> 
> 	perf config call-graph.record-mode=pt
> 
> What do you think?

Adding a --call-graph option sounds reasonable, and config to define default
callgraph options.  But this was done at Andi Kleen's request, so he may
want to comment.