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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
Date: Thu, 18 Jun 2020 21:01:44 -0400	[thread overview]
Message-ID: <20200619010144.GH40119@google.com> (raw)
In-Reply-To: <20200618200138.500b20cb@oasis.local.home>

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


  reply	other threads:[~2020-06-19  1:01 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-18 20:29 [PATCH 1/7] rcu/segcblist: Prevent useless GP start if no CBs to accelerate Joel Fernandes (Google)
2020-06-18 20:29 ` [PATCH 2/7] rcu/trace: Add tracing for how segcb list changes Joel Fernandes (Google)
2020-06-18 22:16   ` Paul E. McKenney
2020-06-18 23:52     ` Joel Fernandes
2020-06-18 20:29 ` [PATCH 3/7] rcu/trace: Add name of the source for gp_seq Joel Fernandes (Google)
2020-06-18 22:19   ` Paul E. McKenney
2020-06-18 23:51     ` Joel Fernandes
2020-06-19  0:12       ` Paul E. McKenney
2020-06-19  0:56         ` Joel Fernandes
2020-06-19  1:08         ` Joel Fernandes
2020-06-19  0:01     ` Steven Rostedt
2020-06-19  1:01       ` Joel Fernandes [this message]
2020-06-18 20:29 ` [PATCH 4/7] rcu/trace: Print negative GP numbers correctly Joel Fernandes (Google)
2020-06-18 22:30   ` Paul E. McKenney
2020-06-18 20:29 ` [PATCH 5/7] rcu/trace: Use rsp's gp_seq in acceleration's rcu_grace_period tracepoint Joel Fernandes (Google)
2020-06-18 22:27   ` Paul E. McKenney
2020-06-18 23:54     ` Joel Fernandes
2020-06-18 20:29 ` [PATCH 6/7] rcutorture: Add support to get the number of wakeups of main GP kthread Joel Fernandes (Google)
2020-06-18 22:40   ` Paul E. McKenney
2020-06-19  0:01     ` Joel Fernandes
2020-06-19  0:12       ` Paul E. McKenney
2020-06-19  1:00         ` Joel Fernandes
2020-06-19  3:23           ` Paul E. McKenney
2020-06-18 20:29 ` [PATCH 7/7] rcutorture: Add number of GP information to reports Joel Fernandes (Google)
2020-06-18 23:27   ` Paul E. McKenney
2020-06-18 22:11 ` [PATCH 1/7] rcu/segcblist: Prevent useless GP start if no CBs to accelerate Paul E. McKenney
2020-06-18 23:09   ` Paul E. McKenney
2020-06-19  0:04     ` Joel Fernandes

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