On Thu, 2013-03-14 at 15:34 +0000, Stephane Eranian wrote: > > Well, the timestamps themselves are already exposed to userspace > > through the ftrace and perf data logs. All people want is to add > > secondary data stream in the same time-line. > > > I agree with Peter on this. The timestamps are already visible. > All we need is the ability to generate them for another user-level > level data stream.
Ok, how about the code below? I must say I have some doubts about the resolution, as there seem to be no generic way of figuring it out for the sched_clock (the arch/arm/kernel/sched_clock.c is actually calculating it, but than just prints it out and nothing more). And, to summarize, we went through 3 ideas: 1. ioctl() - http://article.gmane.org/gmane.linux.kernel/1433933 2. syscall - http://article.gmane.org/gmane.linux.kernel/1437057 3. POSIX clock - below John also suggested that maybe the perf could use CLOCK_MONOTONIC_RAW instead of local/sched_clock(). How about a final decision? Regards Pawel 8<-------------------- >From c986492d38156f1fc25ab3182f0a494bb13389ce Mon Sep 17 00:00:00 2001 From: Pawel Moll <pawel.m...@arm.com> Date: Thu, 14 Mar 2013 19:49:09 +0000 Subject: [PATCH] perf: POSIX CLOCK_PERF to report current time value 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); Signed-off-by: Pawel Moll <pawel.m...@arm.com> --- 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 0d3c0ed..cea16b0 100644 --- a/include/uapi/linux/time.h +++ b/include/uapi/linux/time.h @@ -54,6 +54,7 @@ struct itimerval { #define CLOCK_BOOTTIME 7 #define CLOCK_REALTIME_ALARM 8 #define CLOCK_BOOTTIME_ALARM 9 +#define CLOCK_PERF 10 /* * The IDs of various hardware clocks: diff --git a/kernel/events/core.c b/kernel/events/core.c index b0cd865..81ca459 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -37,6 +37,7 @@ #include <linux/ftrace_event.h> #include <linux/hw_breakpoint.h> #include <linux/mm_types.h> +#include <linux/posix-timers.h> #include "internal.h" @@ -209,6 +210,19 @@ 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) { @@ -7391,6 +7405,10 @@ 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); @@ -7407,6 +7425,8 @@ 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); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
