From: Pawel Moll <pawel.m...@arm.com>
To co-relate user space events with the perf events stream
a current (as in: "what time(stamp) is it now?") time value
must be made available.
This patch adds a POSIX clock returning the perf_clock()
value and accesible from userspace:
#include <time.h>
struct timespec ts;
clock_gettime(CLOCK_PERF, &ts);
Updated to 3.13
Signed-off-by: Pawel Moll <pawel.m...@arm.com>
Signed-off-by: David Ahern <dsah...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: John Stultz <john.stu...@linaro.org>
Cc: Sonny Rao <sonny...@chromium.org>
Cc: Thomas Gleixner <t...@linutronix.de>
---
include/uapi/linux/time.h | 1 +
kernel/events/core.c | 20 ++++++++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h
index e75e1b6ff27f..b07f07914a13 100644
--- a/include/uapi/linux/time.h
+++ b/include/uapi/linux/time.h
@@ -56,6 +56,7 @@ struct itimerval {
#define CLOCK_BOOTTIME_ALARM 9
#define CLOCK_SGI_CYCLE 10 /* Hardware specific */
#define CLOCK_TAI 11
+#define CLOCK_PERF 12
#define MAX_CLOCKS 16
#define CLOCKS_MASK (CLOCK_REALTIME | CLOCK_MONOTONIC)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 72348dc192c1..87aa36ac68f7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -39,6 +39,7 @@
#include <linux/hw_breakpoint.h>
#include <linux/mm_types.h>
#include <linux/cgroup.h>
+#include <linux/posix-timers.h>
#include "internal.h"
@@ -295,6 +296,19 @@ static inline u64 perf_clock(void)
return local_clock();
}
+static int perf_posix_clock_getres(const clockid_t which_clock,
+ struct timespec *tp)
+{
+ *tp = ns_to_timespec(TICK_NSEC);
+ return 0;
+}
+
+static int perf_posix_clock_get(clockid_t which_clock, struct timespec *tp)
+{
+ *tp = ns_to_timespec(perf_clock());
+ return 0;
+}
+
static inline struct perf_cpu_context *
__get_cpu_context(struct perf_event_context *ctx)
{
@@ -7904,6 +7918,10 @@ perf_cpu_notify(struct notifier_block *self, unsigned
long action, void *hcpu)
void __init perf_event_init(void)
{
+ struct k_clock perf_posix_clock = {
+ .clock_getres = perf_posix_clock_getres,
+ .clock_get = perf_posix_clock_get,
+ };
int ret;
idr_init(&pmu_idr);
@@ -7920,6 +7938,8 @@ void __init perf_event_init(void)
ret = init_hw_breakpoint();
WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
+ posix_timers_register_clock(CLOCK_PERF, &perf_posix_clock);
+
/* do not patch jump label more than once per second */
jump_label_rate_limit(&perf_sched_events, HZ);
--
1.8.3.4 (Apple Git-47)
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