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* [PATCH 0/3] Add walltime support for ring-buffer
@ 2009-07-24 10:40 Zhaolei
  2009-07-24 10:42 ` [PATCH] " Zhaolei
                   ` (4 more replies)
  0 siblings, 5 replies; 46+ messages in thread
From: Zhaolei @ 2009-07-24 10:40 UTC (permalink / raw)
  To: Steven Rostedt, Frederic Weisbecker, Ingo Molnar; +Cc: LKML

Hello, Steven

It is a prototype code to make ftrace display walltime of events.

It need to applys on my patch of:
[PATCH v3 1/2] Add function to convert between calendar time and broken-down time for universal use

This code can run but need to be fixed, it only for demostrate what is result
looks like.

I think display walltime is valuable for ftrace, it can provide more
recognizable information to system manager that he can known "when"
event happened.
And it is also helpful for flight-recorder we are doing now, we can get
walltime of events after panic for analyse.

We can get following result on this patch:
 # cd /mnt/debugfs/tracing/
 # echo sched_switch > current_tracer
 # cat trace
 # tracer: sched_switch
 #
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
             bash-2457  [000]   214.895446:   2457:120:S   + [000]  2457:120:S bash
             bash-2457  [000]   214.898298:   2457:120:R   + [000]     5:115:S events/0
             bash-2457  [000]   214.898684:   2457:120:R ==> [000]     5:115:R events/0
         events/0-5     [000]   214.899458:      5:115:R   + [000]  2455:120:S sshd
         events/0-5     [000]   214.899495:      5:115:S ==> [000]  2455:120:R sshd
 ...
 # echo 1 > options/walltime
 # cat trace
 # tracer: sched_switch
 #
 #           TASK-PID    CPU#                  TIMESTAMP  FUNCTION
 #              | |       |                        |         |
           <idle>-0     [000] 2009-07-25 18:01:00.848468:      0:140:R ==> [000]     5:115:R events/0
         events/0-5     [000] 2009-07-25 18:01:00.848523:      5:115:S ==> [000]     0:140:R <idle>
           <idle>-0     [000] 2009-07-25 18:01:01.613479:      0:140:R   + [000]  2455:120:S sshd
           <idle>-0     [000] 2009-07-25 18:01:01.613678:      0:140:R ==> [000]  2455:120:R sshd
             sshd-2455  [000] 2009-07-25 18:01:01.614015:   2455:120:S   + [000]  2455:120:S sshd
 ...

This patch is prototype because we have following things to do:
1: function to get walltime is not near rb_time_stamp()
   So walltime is not absolutely synchronize with trace time.
   But if we place code to get walltime near rb_time_stamp(), it will be called
   on every reserve-event and will make system slow.
2: We can't call getnstimeofday() freely in ring-buffer's code, because
   it is possibility already hold xtime_lock. Prototype code used a ugly way
   to get gid of this problem, maybe we need to ftrace_disable_cpu() before
   every write_seqlock() instead.
3: People maybe change walltime when tracing, but current ring-buffer page's
   walltime can not reflect this change. We need to add tracepoints to watch
   this change, and add a walltime-change event(already reserved in
   ring-buffer.c) to record this change.

I'll continue to finish remain steps, what is your opinion on it?

Thanks
Zhaolei



^ permalink raw reply	[flat|nested] 46+ messages in thread

end of thread, other threads:[~2009-11-04  9:38 UTC | newest]

Thread overview: 46+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-07-24 10:40 [PATCH 0/3] Add walltime support for ring-buffer Zhaolei
2009-07-24 10:42 ` [PATCH] " Zhaolei
2009-07-24 10:47   ` Zhaolei
2009-07-24 10:43 ` [RFC PATCH 1/3] " Zhaolei
2009-07-24 10:43 ` [RFC PATCH 2/3] Apply walltime-supporting functions to trace system Zhaolei
2009-07-24 10:44 ` [RFC PATCH 3/3] Make ftrace display walltime in output Zhaolei
2009-07-24 13:05 ` [PATCH 0/3] Add walltime support for ring-buffer Steven Rostedt
2009-07-28  1:43   ` KOSAKI Motohiro
2009-07-28  1:53     ` Frederic Weisbecker
2009-07-28  2:19       ` Steven Rostedt
2009-08-17  9:22         ` [RFC PATCH] Add timer-source of walltime for ftrace Zhaolei
2009-08-17 16:49           ` Frederic Weisbecker
2009-08-18  2:09             ` Zhaolei
2009-08-18 18:52               ` Steven Rostedt
2009-08-18 15:57           ` KOSAKI Motohiro
2009-08-18 18:58             ` Steven Rostedt
2009-08-19  9:16               ` Zhaolei
2009-08-25  8:12               ` [PATCH 0/3] ftrace: " Zhaolei
2009-08-25  8:12                 ` [PATCH 1/3] ftrace: Move setting of clock-source out of options Zhaolei
2009-08-26  2:35                   ` Steven Rostedt
2009-08-26  7:23                   ` [tip:tracing/core] " tip-bot for Zhaolei
2009-08-25  8:14                 ` [PATCH 2/3] ftrace: add tracepoint for xtime Zhaolei
2009-08-26  2:39                   ` Steven Rostedt
2009-09-01  8:03                     ` Zhaolei
2009-09-16 19:56                   ` john stultz
2009-09-16 19:58                     ` john stultz
2009-09-16 20:32                       ` Steven Rostedt
2009-09-16 20:49                         ` john stultz
2009-09-17  6:34                           ` Zhaolei
2009-08-25  8:15                 ` [PATCH 3/3] ftrace: Add timer-source of walltime for ftrace Zhaolei
2009-08-26  2:52                   ` Steven Rostedt
2009-09-16  5:25                 ` [PATCH v2 0/2] " Zhaolei
2009-09-16  5:27                   ` [PATCH v2 1/2] ftrace: add tracepoint for xtime Zhaolei
2009-09-16 19:33                     ` Steven Rostedt
2009-09-16  5:29                   ` [PATCH v2 2/2] ftrace: Add timer-source of walltime for ftrace Zhaolei
2009-09-16  5:59                     ` Frederic Weisbecker
2009-09-16  6:40                       ` Zhaolei
2009-09-16 19:37                         ` Steven Rostedt
2009-09-17  7:10                           ` Zhaolei
2009-11-04  9:39                             ` [PATCH v3] ftrace: Add timer-source of walltime Zhaolei
2009-11-04  9:39                             ` Zhaolei
2009-11-04  9:41                             ` Zhaolei
2009-07-28  2:23       ` [PATCH 0/3] Add walltime support for ring-buffer KOSAKI Motohiro
2009-08-03  7:22         ` Ingo Molnar
2009-08-03  9:32           ` KOSAKI Motohiro
2009-08-04 14:38             ` Ingo Molnar

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