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Date: Thu, 9 Oct 2008 12:23:13 +0200
From: "=?ISO-8859-1?Q?Fr=E9d=E9ric_Weisbecker?=" <fweisbec@gmail.com>
To: paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH] rudimentary tracing for Classic RCU
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, rjw@sisk.pl,
       dipankar@in.ibm.com, tglx@linuxtronix.de, andi@firstfloor.org
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2008/10/9 Paul E. McKenney <paulmck@linux.vnet.ibm.com>:
> Hello!
>
> This is a tracing patch for Classic RCU, which creates an "rcu/rcucb"
> file in debugfs.  This patch can be handy when you need to work out
> why RCU is refusing to end the current grace period.
>
> Reading from the file results in something like the following:
>
>        rcu: cur=1129  completed=1128  np=0  s=0
>                0,3,7
>        rcu_bh: cur=-287  completed=-287  np=0  s=0
>
>        online: 0-7


Hi Paul,

Why don't you use the ring-buffer tracing engine?
You will really make your life better by putting it as a tracer in
kernel/trace and by using the relevant API.
That will avoid you to manage the debugfs things, the memory
allocation, the buffer managment.....