linux-kernel - Re: [PATCH v1 7/8] perf c2c: Add option '-d llc' for sorting with LLC load

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Message-ID: <20201020072603.GD2084117@krava>
Date:   Tue, 20 Oct 2020 09:26:03 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>, Joe Mario <jmario@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Don Zickus <dzickus@...hat.com>, Al Grant <Al.Grant@....com>,
        James Clark <james.clark@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 7/8] perf c2c: Add option '-d llc' for sorting with
 LLC load

On Thu, Oct 15, 2020 at 03:50:40PM +0100, Leo Yan wrote:
> Except the existed three display options 'tot', 'rmt', 'lcl', this patch
> adds option 'llc' so that can sort on LLC load metrics.  The new
> introduced option can work as a choice if the memory event doesn't
> contain HITM tags.
> 
> For the display with option 'llc', both the "Shared Data Cache Line
> Table" and "Shared Cache Line Distribution Pareto" have difference
> comparing to other three display options.
> 
> For the "Shared Data Cache Line Table", instead of sorting HITM metrics,
> it sorts with the LLC hit metrics "tot_llchit".  In this case, users
> should be interested in LLC related statistics, so the dimensions of
> total LLC hit is used to replace HITM related dimensions.
> 
> For Pareto, every single cache line shows the metrics "cl_llc_hit"
> instead of "cl_rmt_hitm", and the single cache line view is sorted by
> metrics "tot_llchit".

hi,
I'm getting compilation error on newer gcc:

  CC       builtin-c2c.o
builtin-c2c.c: In function ‘perf_c2c__report’:
builtin-c2c.c:1979:9: error: ‘sort_str’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
 1979 |  return hpp_list__parse(&c2c_hists->list, output, sort);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
builtin-c2c.c:2900:27: note: ‘sort_str’ was declared here
 2900 |  const char *output_str, *sort_str;
      |                           ^~~~~~~~


jirka