linux-kernel - Re: [PATCH 3/5] trace: Add per

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Date:	Fri, 29 Jul 2011 14:14:07 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Vaibhav Nagarnaik <vnagarnaik@...gle.com>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Michael Rubin <mrubin@...gle.com>,
	David Sharp <dhsharp@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] trace: Add per_cpu ring buffer control files

On Tue, 2011-07-26 at 15:59 -0700, Vaibhav Nagarnaik wrote:
> Add a debugfs entry under per_cpu/ folder for each cpu called
> buffer_size_kb to control the ring buffer size for each CPU
> independently.
> 
> If the global file buffer_size_kb is used to set size, the individual
> ring buffers will be adjusted to the given size. The buffer_size_kb will
> report the common size to maintain backward compatibility.
> 
> If the buffer_size_kb file under the per_cpu/ directory is used to
> change buffer size for a specific CPU, only the size of the respective
> ring buffer is updated. When tracing/buffer_size_kb is read, it reports
> the ring buffer sizes of all the CPUs at that point.

No, buffer_size_kb should not change in the what it reports. This is why
you have a buffer_total_size_kb. Use that. If the per_cpu buffers are
changed, then this should just report "various" or something to that
affect. This will be a good way to know if the per_cpu buffers are the
same or not.

-- Steve


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