From 9132d3d92d8953ee79690408a9a24d938be22cd8 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 25 May 2018 11:27:38 -0300 Subject: perf annotate: Add comment about annotated_src->nr_histograms When we have multiple groups in an evlist, say: $ perf stat -e '{cycles,instructions},{cache-references,cache-misses}' sleep 1 Performance counter stats for 'sleep 1': 343,134 cycles:u 249,292 instructions:u # 0.73 insn per cycle 15,556 cache-references:u 8,925 cache-misses:u # 57.373 % of all cache refs 1.000957550 seconds time elapsed $ Then the perf_evsel instances for the two group leaders ("cycles" and "cache-references") will have evsel->nr_members set to 2, while all the evsel->evlist->nr_entries will be set to 4, so we can't use evsel->evlist->nr_entries everywhere, as event groups need to be taken into account. But this probably requires us to audit at least the forced-group code, where we want all of the events to be in a "group", to see them all in the screen, one column for each, even knowing that they were not necessarily scheduled to count at the same time by the kernel perf subsystem. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-2g0vwqnc49wl4ttjk8dvpgcc@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/annotate.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools') diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h index 7ad503fbff74..3dc4ca1d6c08 100644 --- a/tools/perf/util/annotate.h +++ b/tools/perf/util/annotate.h @@ -202,6 +202,10 @@ struct cyc_hist { /** struct annotated_source - symbols with hits have this attached as in sannotation * * @histograms: Array of addr hit histograms per event being monitored + * nr_histograms: This may not be the same as evsel->evlist->nr_entries if + * we have more than a group in a evlist, where we will want + * to see each group separately, that is why symbol__annotate2() + * sets src->nr_histograms to evsel->nr_members. * @lines: If 'print_lines' is specified, per source code line percentages * @source: source parsed from a disassembler like objdump -dS * @cyc_hist: Average cycles per basic block -- cgit v1.2.3