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Re: Help with trace-cmd/ftrace recording process ID information

From Steven Rostedt <rostedt@goodmis.org>
Newsgroups linux.kernel
Subject Re: Help with trace-cmd/ftrace recording process ID information
Date 2017-07-17 22:20 +0200
Message-ID <u4kEO-1f3-19@gated-at.bofh.it> (permalink)
References <u4jIK-Dg-23@gated-at.bofh.it> <u4kls-SQ-19@gated-at.bofh.it> <u4kv7-1bl-15@gated-at.bofh.it>
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On Mon, 17 Jul 2017 16:06:37 -0400
Will Hawkins <hawkinsw@borlaugic.com> wrote:


> This seems to be the problem:
> 
> On the "good" system, that file is up-to-date with cached PIDs and
> comms. On the bad host, there are no cached entries from any of the
> traces that I've run.
> 
> Because these are running old kernels, there is no saved_cmdlines_size
> knob to turn. Do you have any idea why the saved_cmdlines would not be
> getting updated appropriately on the "bad" host? I know this is not
> ideal, but I can try to reboot that host and see if something is

Yeah, a reboot may work.

> simply wedged. The system has been online for almost a year, so it's
> possible that something has gone wrong.
> 
> Any help you can offer would be great! Thank you, again, for your response!

The recording of command lines only happens when tracing is done, and
there were a few bugs with the older kernels that caused it to either
stop and never start again, or to simply just miss a bunch of recording.

It may be that it stopped and never started again, so you will only
have a stale file.

-- Steve

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Thread

Help with trace-cmd/ftrace recording process ID information Will Hawkins <hawkinsw@borlaugic.com> - 2017-07-17 21:20 +0200
  Re: Help with trace-cmd/ftrace recording process ID information Steven Rostedt <rostedt@goodmis.org> - 2017-07-17 22:00 +0200
    Re: Help with trace-cmd/ftrace recording process ID information Will Hawkins <hawkinsw@borlaugic.com> - 2017-07-17 22:10 +0200
      Re: Help with trace-cmd/ftrace recording process ID information Will Hawkins <hawkinsw@borlaugic.com> - 2017-07-17 22:10 +0200
      Re: Help with trace-cmd/ftrace recording process ID information Steven Rostedt <rostedt@goodmis.org> - 2017-07-17 22:20 +0200
        Re: Help with trace-cmd/ftrace recording process ID information Will Hawkins <hawkinsw@borlaugic.com> - 2017-07-18 00:40 +0200
          Re: Help with trace-cmd/ftrace recording process ID information Steven Rostedt <rostedt@goodmis.org> - 2017-07-18 02:50 +0200

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