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Date:   Thu, 18 Jun 2020 21:01:44 -0400
From:   Joel Fernandes <joel@joelfernandes.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     "Paul E. McKenney" <paulmck@kernel.org>,
        linux-kernel@vger.kernel.org, Davidlohr Bueso <dave@stgolabs.net>,
        Ingo Molnar <mingo@redhat.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Marco Elver <elver@google.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        rcu@vger.kernel.org, "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Subject: Re: [PATCH 3/7] rcu/trace: Add name of the source for gp_seq
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References: <20200618202955.4024-1-joel@joelfernandes.org>
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 <20200618221901.GZ2723@paulmck-ThinkPad-P72>
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On Thu, Jun 18, 2020 at 08:01:38PM -0400, Steven Rostedt wrote:
> On Thu, 18 Jun 2020 15:19:01 -0700
> "Paul E. McKenney" <paulmck@kernel.org> wrote:
> 
> > For future reference, the TPS() around strings is not optional.  Without
> > it, trace messages from crash dumps are garbled, if I remember correctly.
> 
> When you pass in a string like this, only the pointer to the string is
> saved in the ring buffer. User space tools have no idea what those
> pointers are. The TPS() around strings maps those pointers to the
> string and shows them in the /sys/kernel/tracing/printk_formats file,
> such that perf and trace-cmd know how to make sense of those strings.

Makes sense. Quite a valuable feature!

thanks,

 - Joel