Re: [PATCH 2/3] ftrace: add tracepoint for xtime

Steven Rostedt
2009-08-26T02:39:18Z

Thomas,

This patch touches time keeping work. Can I get your ACK on it, or if it
belongs to someone else, could you tell me who I need.

Thanks,

-- Steve

On Tue, 25 Aug 2009, Zhaolei wrote:

> From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
>
> This patch can trace current xtime and wall_to_monotonic. Then user can
> use ctime() to convert them to wall time which is easier to be understood,
> especially for flight-recorder which need to get trace event from a kernel
> dump file.
>
> Example of ftrace output:
> <idle>-0 [000] 20118.489849: gtod_update_xtime: xtime=1243265589.999999824 wall_to_monotonic=3051713268.744158739
> <...>-4020 [001] 20118.489855: sys_open(filename: bf9e66e0, flags: 98800, mode: bf9e66e0)
> <...>-4020 [001] 20118.489873: sys_open -> 0xffffffec
>
> ctime(1243265590) = date:Mon May 25 11:33:10 2009
> So we can realize the task with pid 4020 open a file at
> Mon May 25 11:33:10 2009
>
> Changelog:
> v1->v2: Rebased by Zhao Lei <zhaolei@cn.fujitsu.com>
>
> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
> include/trace/events/xtime.h | 38 ++++++++++++++++++++++++++++++++++++++
> kernel/time/ntp.c | 4 ++++
> kernel/time/timekeeping.c | 6 ++++++
> 3 files changed, 48 insertions(+), 0 deletions(-)
> create mode 100644 include/trace/events/xtime.h
>
> diff --git a/include/trace/events/xtime.h b/include/trace/events/xtime.h
> new file mode 100644
> index 0000000..398e679
> --- /dev/null
> +++ b/include/trace/events/xtime.h
> @@ -0,0 +1,38 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM xtime
> +
> +#if !defined(_TRACE_XTIME_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_XTIME_H
> +
> +#include <linux/time.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(gtod_update_xtime,
> +
> + TP_PROTO(struct timespec *xtime, struct timespec *wall_to_monotonic),
> +
> + TP_ARGS(xtime, wall_to_monotonic),
> +
> + TP_STRUCT__entry(
> + __field( long, xtime_sec )
> + __field( long, xtime_nsec )
> + __field( long, wall_to_monotonic_sec )
> + __field( long, wall_to_monotonic_nsec )
> + ),
> +
> + TP_fast_assign(
> + __entry->xtime_sec = xtime->tv_sec;
> + __entry->xtime_nsec = xtime->tv_nsec;
> + __entry->wall_to_monotonic_sec = wall_to_monotonic->tv_sec;
> + __entry->wall_to_monotonic_nsec = wall_to_monotonic->tv_nsec;
> + ),
> +
> + TP_printk("xtime=%ld.%09ld wall_to_monotonic=%ld.%09ld",
> + __entry->xtime_sec, __entry->xtime_nsec,
> + __entry->wall_to_monotonic_sec, __entry->wall_to_monotonic_nsec)
> +);
> +
> +#endif /* _TRACE_XTIME_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
> index 4800f93..fc2f13a 100644
> --- a/kernel/time/ntp.c
> +++ b/kernel/time/ntp.c
> @@ -15,6 +15,8 @@
> #include <linux/time.h>
> #include <linux/mm.h>
>
> +#include <trace/events/xtime.h>
> +
> /*
> * NTP timekeeping variables:
> */
> @@ -218,6 +220,8 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
> break;
> }
>
> + trace_gtod_update_xtime(&xtime, &wall_to_monotonic);
> +
> write_sequnlock(&xtime_lock);
>
> return res;
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index 03cbeb3..2e57a87 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -20,6 +20,9 @@
> #include <linux/tick.h>
> #include <linux/stop_machine.h>
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/xtime.h>
> +
> /* Structure holding internal timekeeping values. */
> struct timekeeper {
> /* Current clocksource used for timekeeping. */
> @@ -338,6 +341,8 @@ int do_settimeofday(struct timespec *tv)
>
> update_vsyscall(&xtime, timekeeper.clock);
>
> + trace_gtod_update_xtime(&xtime, &wall_to_monotonic);
> +
> write_sequnlock_irqrestore(&xtime_lock, flags);
>
> /* signal hrtimers about time change */
> @@ -811,6 +816,7 @@ void update_wall_time(void)
>
> /* check to see if there is a new clocksource to use */
> update_vsyscall(&xtime, timekeeper.clock);
> + trace_gtod_update_xtime(&xtime, &wall_to_monotonic);
> }
>
> /**
> --
> 1.5.5.3
>
>