linux-kernel - Re: [PATCH 6/7] perf report: mark inlined frames in output by " (inlined)" suffix

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Date:   Tue, 06 Jun 2017 09:26:47 +0200
From:   Milian Wolff <milian.wolff@...b.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <Linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Yao Jin <yao.jin@...ux.intel.com>, kernel-team@....com
Subject: Re: [PATCH 6/7] perf report: mark inlined frames in output by " (inlined)" suffix

On Tuesday, June 6, 2017 3:33:49 AM CEST Namhyung Kim wrote:
> On Sat, Jun 3, 2017 at 10:51 PM, Milian Wolff <milian.wolff@...b.com> wrote:
> > On Montag, 22. Mai 2017 14:48:18 CEST Namhyung Kim wrote:
> >> On Thu, May 18, 2017 at 09:34:10PM +0200, Milian Wolff wrote:
> >> > The original patch that introduced inline frame output in the
> >> > various browsers used this suffix already. The new centralized
> >> > approach that uses fake symbols for inlined frames was missing
> >> > this approach so far.
> >> > 
> >> > Instead of changing the symbol name itself, we only print the
> >> > suffix where needed. This allows us to efficiently lookup
> >> > the symbol for a given name without first having to append the
> >> > suffix before the lookup.
> >> 
> >> You also need to do same thing for hist_entry__sym_snprintf().
> > 
> > Hey Namhyung,
> > 
> > I'm working on the next iteration of this patch series, the WIP can be
> > found here:
> > https://github.com/milianw/linux/tree/wip/distinguish-inliners.
> > 
> > I just stumbled upon another issue:
> > 
> > ~~~~~
> > perf report --inline -s srcline -g srcline  --stdio -g none
> > 
> >     61.22%     0.00%  main+378
> >     61.22%     0.00%  std::_Norm_helper<true>::_S_do_it<double>+378
> >     61.22%     0.00%  std::__complex_abs+378
> >     61.22%     0.00%  std::abs<double>+378
> >     61.22%     0.00%  std::norm<double>+378
> > 
> > ~~~~~
> > 
> > The problem here is that the srcline in the hist is detached from what we
> > actually produce in the callchain nodes. We will have to somehow hand
> > through the srcline from the callchain node to the hist entry, but this
> > seems to be a super large invasive change - which is why I need your
> > input on how to resolve this.
> > 
> > The current API seems to pass the data around mostly using the
> > addr_location struct, which is usually constructed on the stack and not
> > always memset to zero. As such, my initial plan of adding a srcline
> > member there would require me to go through all the code to ensure that
> > we memset the struct to zero...
> > 
> > Alternatively, I'd have to change the API of hist_iter_ops, to let the
> > callback take another `const char **srcline` out parameter. This is also
> > going to be quite a large invasive change.
> > 
> > Do you have any suggestions on how to make this work?
> 
> I think passing srcline via addr_location might not be very invasive
> since it calls machine__resolve() in most cases.  Missing places that
> set al->sym should set al->srcline as well IMHO.

OK, perfect - I'll implement that then.

Cheers

-- 
Milian Wolff | milian.wolff@...b.com | Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt Experts
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