Fixes bug noted by Jiri in https://lkml.org/lkml/2017/6/13/755 and caused by commit d49dadea7862 ("perf tools: Make 'trace' or 'trace_fields' sort key default for tracepoint events") not taking into account that evlist is empty in pipe-mode.
Before this commit, pipe mode will only show bogus "100.00% N/A" instead of correct output as follows: $ perf record -o - sleep 1 | perf report -i - # To display the perf.data header info, please use --header/--header-only options. # [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.000 MB - ] # # Total Lost Samples: 0 # # Samples: 8 of event 'cycles:ppH' # Event count (approx.): 145658 # # Overhead Trace output # ........ ............ # 100.00% N/A Correct output, after patch: $ perf record -o - sleep 1 | perf report -i - # To display the perf.data header info, please use --header/--header-only options. # [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.000 MB - ] # # Total Lost Samples: 0 # # Samples: 8 of event 'cycles:ppH' # Event count (approx.): 191331 # # Overhead Command Shared Object Symbol # ........ ....... ................. ................................. # 81.63% sleep libc-2.19.so [.] _exit 13.58% sleep ld-2.19.so [.] do_lookup_x 2.34% sleep [kernel.kallsyms] [k] context_switch 2.34% sleep libc-2.19.so [.] __GI___libc_nanosleep 0.11% perf [kernel.kallsyms] [k] __intel_pmu_enable_a Signed-off-by: David Carrillo-Cisneros <davi...@google.com> --- tools/perf/util/evlist.h | 5 +++++ tools/perf/util/sort.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index 0843746bc389..bf2c4936e35f 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -265,6 +265,11 @@ bool perf_evlist__valid_read_format(struct perf_evlist *evlist); void perf_evlist__splice_list_tail(struct perf_evlist *evlist, struct list_head *list); +static inline bool perf_evlist__empty(struct perf_evlist *evlist) +{ + return list_empty(&evlist->entries); +} + static inline struct perf_evsel *perf_evlist__first(struct perf_evlist *evlist) { return list_entry(evlist->entries.next, struct perf_evsel, node); diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c index 8b327c955a4f..12359bd986db 100644 --- a/tools/perf/util/sort.c +++ b/tools/perf/util/sort.c @@ -2563,7 +2563,7 @@ static const char *get_default_sort_order(struct perf_evlist *evlist) BUG_ON(sort__mode >= ARRAY_SIZE(default_sort_orders)); - if (evlist == NULL) + if (evlist == NULL || perf_evlist__empty(evlist)) goto out_no_evlist; evlist__for_each_entry(evlist, evsel) { -- 2.14.0.rc0.284.gd933b75aa4-goog