Re: [PATCH 3/3] ftrace: Add timer-source of walltime for ftrace

Steven Rostedt
2009-08-26T02:52:23Z

On Tue, 25 Aug 2009, Zhaolei wrote:

> We can add a timer-source for ftrace to support wall-time display.
> It is based on Steven Rostedt <rostedt@goodmis.org>'s suggestion in:
> http://lkml.org/lkml/2009/7/24/103
>
> It need to applys on my patch of:
> [PATCH v4 1/2] Add function to convert between calendar time and broken-down time for universal use
>
> We can get following output:
> # cd /mnt/debugfs/tracing/
> # cat trace_clock
> [local] global walltime
> # echo sched_switch > current_tracer
> # cat trace
> # tracer: sched_switch
> #
> # TASK-PID CPU# TIMESTAMP FUNCTION
> # | | | | |
> bash-3580 [000] 2916.188093: 3580:120:S + [000] 3580:120:S bash
> bash-3580 [000] 2916.188205: 3580:120:S + [000] 3580:120:S bash
> bash-3580 [000] 2916.188538: 3580:120:R + [000] 5:115:S events/0
> bash-3580 [000] 2916.188599: 3580:120:R ==> [000] 5:115:R events/0
> events/0-5 [000] 2916.188669: 5:115:S ==> [000] 3580:120:R bash
> ...
> # echo walltime > trace_clock
> # cat trace
> # tracer: sched_switch
> #
> # TASK-PID CPU# TIMESTAMP FUNCTION
> # | | | | |
> bash-3580 [000] 2009-08-24 18:03:16.500705: 3580:120:S + [000] 3580:120:S bash
> bash-3580 [000] 2009-08-24 18:03:16.500815: 3580:120:S + [000] 3580:120:S bash
> bash-3580 [000] 2009-08-24 18:03:16.500815: 3580:120:S + [000] 3580:120:S bash
> bash-3580 [000] 2009-08-24 18:03:16.500815: 3580:120:S ==> [000] 5:115:R events/0
> events/0-5 [000] 2009-08-24 18:03:16.500815: 5:115:R + [000] 3578:120:S sshd
> ...
>
> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>

> +
> +static int __init walltime_init(void)
> +{
> + unsigned long flags;
> + struct timespec ts;
> + u64 traceclock;
> +
> + local_irq_save(flags);
> + getnstimeofday(&ts);
> + traceclock = trace_clock();
> + sync_base_walltime(&ts, traceclock);
> + local_irq_restore(flags);
> +
> + register_trace_gtod_update_xtime(probe_gtod_update_xtime);

Because this patch depends on patch 2 that creates the "gtod_update_xtime"
trace point, I have to hold off on this one too. But the first patch is a
nice clean up regardless. I'll pull that one in.

Thanks,

-- Steve

> +
> + return 0;
> +}
> +device_initcall_sync(walltime_init);
> +
> +u64 notrace trace_clock_walltime(void)
> +{
> + return base_walltime + trace_clock();
> +}