From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Rogers Subject: [PATCH] perf record: add dummy event during system wide synthesis Date: Wed, 15 Apr 2020 17:47:13 -0700 Message-ID: <20200416004713.192740-1-irogers@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Kan Liang , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: Stephane Eranian , Ian Rogers List-Id: linux-perf-users.vger.kernel.org During the processing of /proc during event synthesis new processes may start. Add a dummy event if /proc is to be processed, to capture mmaps for starting processes. This reuses the existing logic for initial-delay. Suggested-by: Stephane Eranian Signed-off-by: Ian Rogers --- tools/perf/builtin-record.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 1ab349abe904..bab4fc8568d1 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -805,16 +805,18 @@ static int record__open(struct record *rec) int rc = 0; /* - * For initial_delay we need to add a dummy event so that we can track - * PERF_RECORD_MMAP while we wait for the initial delay to enable the - * real events, the ones asked by the user. + * For initial_delay or system wide, we need to add a dummy event so + * that we can track PERF_RECORD_MMAP to cover the delay (of waiting or + * synthesis) prior to the real user events being enabled. */ - if (opts->initial_delay) { + if (opts->initial_delay || target__has_cpu(&opts->target)) { if (perf_evlist__add_dummy(evlist)) return -ENOMEM; + /* Disable tracking of mmaps on lead event. */ pos = evlist__first(evlist); pos->tracking = 0; + /* Activate dummy event immediately. */ pos = evlist__last(evlist); pos->tracking = 1; pos->core.attr.enable_on_exec = 1; -- 2.26.0.110.g2183baf09c-goog