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Subject[PATCH 1/6] perf events: Introduce realtime clock event
Date
The motivation for this event is to correlate perf_clock() time stamps
to wall-clock (gettimeofday()) equivalents for comparing perf events
to other log files.

This patch is based on the monotonic patch by Arnaldo Carvalho de Melo
<acme@redhat.com>.

Signed-off-by: David Ahern <daahern@cisco.com>
---
include/linux/perf_event.h | 1 +
kernel/perf_event.c | 66 ++++++++++++++++++++++++++++++++++++++++
tools/perf/util/parse-events.c | 2 +
3 files changed, 69 insertions(+), 0 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 8ceb5a6..51a2f34 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -105,6 +105,7 @@ enum perf_sw_ids {
PERF_COUNT_SW_PAGE_FAULTS_MAJ = 6,
PERF_COUNT_SW_ALIGNMENT_FAULTS = 7,
PERF_COUNT_SW_EMULATION_FAULTS = 8,
+ PERF_COUNT_SW_REALTIME_CLOCK = 9,

PERF_COUNT_SW_MAX, /* non-ABI */
};
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 64a018e..a25a63d 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5432,6 +5432,7 @@ static int perf_swevent_init(struct perf_event *event)
switch (event_id) {
case PERF_COUNT_SW_CPU_CLOCK:
case PERF_COUNT_SW_TASK_CLOCK:
+ case PERF_COUNT_SW_REALTIME_CLOCK:
return -ENOENT;

default:
@@ -5770,6 +5771,70 @@ static struct pmu perf_cpu_clock = {
};

/*
+ * Software event: realtime wall time clock
+ */
+
+static void realtime_clock_event_update(struct perf_event *event)
+{
+ u64 now = ktime_to_ns(ktime_get_real());
+ local64_set(&event->count, now);
+}
+
+static void realtime_clock_event_start(struct perf_event *event, int flags)
+{
+ realtime_clock_event_update(event);
+ perf_swevent_start_hrtimer(event);
+}
+
+static void realtime_clock_event_stop(struct perf_event *event, int flags)
+{
+ perf_swevent_cancel_hrtimer(event);
+ realtime_clock_event_update(event);
+}
+
+static int realtime_clock_event_add(struct perf_event *event, int flags)
+{
+ if (flags & PERF_EF_START)
+ realtime_clock_event_start(event, flags);
+
+ return 0;
+}
+
+static void realtime_clock_event_del(struct perf_event *event, int flags)
+{
+ realtime_clock_event_stop(event, flags);
+}
+
+static void realtime_clock_event_read(struct perf_event *event)
+{
+ realtime_clock_event_update(event);
+}
+
+static int realtime_clock_event_init(struct perf_event *event)
+{
+ if (event->attr.type != PERF_TYPE_SOFTWARE)
+ return -ENOENT;
+
+ if (event->attr.config != PERF_COUNT_SW_REALTIME_CLOCK)
+ return -ENOENT;
+
+ perf_swevent_init_hrtimer(event);
+
+ return 0;
+}
+
+static struct pmu perf_realtime_clock = {
+ .task_ctx_nr = perf_sw_context,
+
+ .event_init = realtime_clock_event_init,
+ .add = realtime_clock_event_add,
+ .del = realtime_clock_event_del,
+ .start = realtime_clock_event_start,
+ .stop = realtime_clock_event_stop,
+ .read = realtime_clock_event_read,
+};
+
+/*
* Software event: task time clock
*/

@@ -7296,6 +7361,7 @@ void __init perf_event_init(void)
init_srcu_struct(&pmus_srcu);
perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE);
perf_pmu_register(&perf_cpu_clock, NULL, -1);
+ perf_pmu_register(&perf_realtime_clock, NULL, -1);
perf_pmu_register(&perf_task_clock, NULL, -1);
perf_tp_register();
perf_cpu_notifier(perf_cpu_notify);
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 54a7e26..c40bfef 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -41,6 +41,7 @@ static struct event_symbol event_symbols[] = {

{ CSW(CPU_CLOCK), "cpu-clock", "" },
{ CSW(TASK_CLOCK), "task-clock", "" },
+ { CSW(REALTIME_CLOCK), "clock-realtime", "clkr" },
{ CSW(PAGE_FAULTS), "page-faults", "faults" },
{ CSW(PAGE_FAULTS_MIN), "minor-faults", "" },
{ CSW(PAGE_FAULTS_MAJ), "major-faults", "" },
@@ -78,6 +79,7 @@ static const char *sw_event_names[] = {
"major-faults",
"alignment-faults",
"emulation-faults",
+ "realtime-clock-msecs",
};

#define MAX_ALIASES 8
--
1.7.4


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