linux-stable.git/kernel/trace/trace_irqsoff.c, branch linux-2.6.31.y

tracing: have latency tracers set the latency format

2009-03-05T03:15:30+00:00

The latency tracers (irqsoff, preemptoff, preemptirqsoff, and wakeup)
are pretty useless with the default output format. This patch makes them
automatically enable the latency format when they are selected. They
also record the state of the latency option, and if it was not enabled
when selected, they disable it on reset.

Signed-off-by: Steven Rostedt

tracing: fix typing mistake in hint message and comments

2009-02-17T17:38:24+00:00

Impact: cleanup

Fix incorrect hint message in code and typos in comments.

Signed-off-by: Wenji Huang 
Signed-off-by: Steven Rostedt

trace: Remove unused trace_array_cpu parameter

2009-02-05T13:35:47+00:00

Impact: cleanup

Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar

trace: remove internal irqsoff disabling for trace output

2009-01-23T10:10:36+00:00

Impact: cleanup of duplicate features

The trace output disables the ring buffer and prevents tracing to
occur. The code in irqsoff to do the same thing is no longer needed.
This patch removes it.

Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar

trace: set max latency variable to zero on default

2009-01-16T11:18:09+00:00

Impact: trace max latencies on start of latency tracing

This patch sets the max latency to zero whenever one of the
irq variant tracers or the wakeup tracer is set to current tracer.

Most developers expect to see output when starting up a latency
tracer. But since the max_latency is already set to max, and
it takes a latency greater than max_latency to be recorded, there
is no trace. This is not the expected behavior and has even confused
myself.

Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar

tracing/ftrace: change the type of the init() callback

2008-11-16T06:55:23+00:00

Impact: extend the ->init() method with the ability to fail

This bring a way to know if the initialization of a tracer successed.
A tracer must return 0 on success and a traditional error (ie:
-ENOMEM) if it fails.

If a tracer fails to init, it is free to print a detailed warn. The
tracing api will not and switch to a new tracer will just return the
error from the init callback.

Note: this will be used for the return tracer.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: Ingo Molnar

ftrace: remove trace array ctrl

2008-11-08T08:51:39+00:00

Impact: remove obsolete variable in trace_array structure

With the new start / stop method of ftrace, the ctrl variable
in the trace_array structure is now obsolete. Remove it.

Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar

ftrace: remove ctrl_update method

2008-11-08T08:51:34+00:00

Impact: Remove the ctrl_update tracer method

With the new quick start/stop method of tracing, the ctrl_update
method is out of date.

Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar

ftrace: irqsoff tracer incorrect reset

2008-11-08T08:51:24+00:00

Impact: fix to irqsoff tracer output

In converting to the new start / stop ftrace handling, the irqsoff
tracer start called the irqsoff reset function. irqsoff tracer is
not the same as the other traces, and it resets the buffers while
searching for the longest latency.

The reset that the irqsoff stop method calls disables the function
tracing. That means that, by starting the tracer, the function
tracer is disabled incorrectly.

This patch simply removes the call to reset which keeps the function
tracing enabled. Reset is not needed for the irqsoff stop method.

Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar

ftrace: restructure tracing start/stop infrastructure

2008-11-06T06:51:03+00:00

Impact: change where tracing is started up and stopped

Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.

The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.

This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.

For example, the startup of a tracer may enable tracepoints, or enable
the function tracer.  The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called.  The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.

The tracing_enabled file will simply start or stop tracing.

This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling  tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.

This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.

Note: There were two methods to the struct tracer that were never
 used: The methods start and stop. These were to be used as a hook
 to the reading of the trace output, but ended up not being
 necessary. These two methods are now used to enable the start
 and stop of each tracer, in case the tracer needs to do more than
 just not write into the buffer. For example, the irqsoff tracer
 must stop recording max latencies when tracing is stopped.

Signed-off-by: Steven Rostedt 
Signed-off-by: Ingo Molnar