Re: [PATCH v2 0/4] ftrace: important updates

From: Ingo Molnar
Date: Wed Jan 07 2009 - 04:49:35 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> Ingo,
>
> The first patch is a critical fix that needs to get into 2.6.29.
>
> The next patch is a rename of tracing_on to writing_enabled since
> tracing_on is confusing, and the file enables or disables writes.
>
> The last patch is a fix to tip that prevents a memory leak.
>
> This version I added some clean ups that Andrew Morton suggested.
> I know you did not pull the previous version, because I forgot
> to push the changes to kernel.org ;-)
>
> The following patches are in:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
>
> branch: tip/devel
>
>
> Frederic Weisbecker (1):
> tracing/ftrace: fix a memory leak in stat tracing
>
> Steven Rostedt (3):
> ftrace: convert unsigned index to signed
> trace: clean up funny line breaks in stat_seq_show

pulled most of it, thanks Steve, except this bit:

> ring-buffer: rename debugfs file tracing_on to writing_enabled

writing_enabled is at least as confusing as tracing_on - if not more so.

The user really does not care about all the deeper machinery that happens
in ftrace - the difference between a 'light' disabling of a tracer and a
'heavy' disabling of a tracer (which means it unregisters itself
completely in essence).

To resolve this, we should probably hide this difference altogether (as i
have suggested to do many months ago, when this first came up), by
removing tracing_enabled.

A tracer can still be fully unregistered: by simply switching the current
tracer to the 'nop' tracer. tracing_on/off remains the lightweight version
that most users are interested in anyway.

Ingo
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