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Message-Id: <20231121000420.368075-1-irogers@google.com>
Date: Mon, 20 Nov 2023 16:04:20 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>,
Yang Jihong <yangjihong1@...wei.com>,
Leo Yan <leo.yan@...aro.org>,
Sandipan Das <sandipan.das@....com>,
Ravi Bangoria <ravi.bangoria@....com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Ajay Kaher <akaher@...are.com>,
Alexey Makhalov <amakhalov@...are.com>
Subject: [RFC PATCH v2] perf evsel: Fallback to task-clock when not system wide
When the cycles event isn't available evsel will fallback to the
cpu-clock software event. task-clock is similar to cpu-clock but only
runs when the process is running. Falling back to cpu-clock when not
system wide leads to confusion, by falling back to task-clock it is
hoped the confusion is less.
Pass the target to determine if task-clock is more appropriate. Update
a nearby comment and debug string for the change.
---
v2. Use target__has_cpu as suggested by Namhyung.
https://lpc.events/event/17/contributions/1556/
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/builtin-record.c | 2 +-
tools/perf/builtin-stat.c | 2 +-
tools/perf/builtin-top.c | 2 +-
tools/perf/util/evsel.c | 18 ++++++++++--------
tools/perf/util/evsel.h | 3 ++-
5 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 8ec818568662..d8bb59511fdd 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1350,7 +1350,7 @@ static int record__open(struct record *rec)
evlist__for_each_entry(evlist, pos) {
try_again:
if (evsel__open(pos, pos->core.cpus, pos->core.threads) < 0) {
- if (evsel__fallback(pos, errno, msg, sizeof(msg))) {
+ if (evsel__fallback(pos, &opts->target, errno, msg, sizeof(msg))) {
if (verbose > 0)
ui__warning("%s\n", msg);
goto try_again;
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index a3af805a1d57..d8e5d6f7a87a 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -653,7 +653,7 @@ static enum counter_recovery stat_handle_error(struct evsel *counter)
if ((evsel__leader(counter) != counter) ||
!(counter->core.leader->nr_members > 1))
return COUNTER_SKIP;
- } else if (evsel__fallback(counter, errno, msg, sizeof(msg))) {
+ } else if (evsel__fallback(counter, &target, errno, msg, sizeof(msg))) {
if (verbose > 0)
ui__warning("%s\n", msg);
return COUNTER_RETRY;
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ea8c7eca5eee..1e42bd1c7d5a 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1044,7 +1044,7 @@ static int perf_top__start_counters(struct perf_top *top)
perf_top_overwrite_fallback(top, counter))
goto try_again;
- if (evsel__fallback(counter, errno, msg, sizeof(msg))) {
+ if (evsel__fallback(counter, &opts->target, errno, msg, sizeof(msg))) {
if (verbose > 0)
ui__warning("%s\n", msg);
goto try_again;
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index a5da74e3a517..532f34d9fcb5 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2853,7 +2853,8 @@ u64 evsel__intval_common(struct evsel *evsel, struct perf_sample *sample, const
#endif
-bool evsel__fallback(struct evsel *evsel, int err, char *msg, size_t msgsize)
+bool evsel__fallback(struct evsel *evsel, struct target *target, int err,
+ char *msg, size_t msgsize)
{
int paranoid;
@@ -2861,18 +2862,19 @@ bool evsel__fallback(struct evsel *evsel, int err, char *msg, size_t msgsize)
evsel->core.attr.type == PERF_TYPE_HARDWARE &&
evsel->core.attr.config == PERF_COUNT_HW_CPU_CYCLES) {
/*
- * If it's cycles then fall back to hrtimer based
- * cpu-clock-tick sw counter, which is always available even if
- * no PMU support.
+ * If it's cycles then fall back to hrtimer based cpu-clock sw
+ * counter, which is always available even if no PMU support.
*
* PPC returns ENXIO until 2.6.37 (behavior changed with commit
* b0a873e).
*/
- scnprintf(msg, msgsize, "%s",
-"The cycles event is not supported, trying to fall back to cpu-clock-ticks");
-
evsel->core.attr.type = PERF_TYPE_SOFTWARE;
- evsel->core.attr.config = PERF_COUNT_SW_CPU_CLOCK;
+ evsel->core.attr.config = target__has_cpu(target)
+ ? PERF_COUNT_SW_CPU_CLOCK
+ : PERF_COUNT_SW_TASK_CLOCK;
+ scnprintf(msg, msgsize,
+ "The cycles event is not supported, trying to fall back to %s",
+ target__has_cpu(target) ? "cpu-clock" : "task-clock");
zfree(&evsel->name);
return true;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index f19ac9f027ef..efbb6e848287 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -460,7 +460,8 @@ static inline bool evsel__is_clock(const struct evsel *evsel)
evsel__match(evsel, SOFTWARE, SW_TASK_CLOCK);
}
-bool evsel__fallback(struct evsel *evsel, int err, char *msg, size_t msgsize);
+bool evsel__fallback(struct evsel *evsel, struct target *target, int err,
+ char *msg, size_t msgsize);
int evsel__open_strerror(struct evsel *evsel, struct target *target,
int err, char *msg, size_t size);
--
2.43.0.rc1.413.gea7ed67945-goog
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