implement globally synchronized, fast and scalable time source for tracing.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
we can hold all cpu trace buffer locks at once - put each into a
separate lock class.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch creates a file called trace_pipe in the tracing
debug directory. This file is a consumer of the trace buffers.
This means that reads of this file consumes the entries from
the trace buffers so that they will not be read a second time,
as contrast to the static buffers latency_trace and trace.
Reading from the trace_pipe will remove the entries from trace
and latency_trace too.
The advantage that trace_pipe has is that it can record live
traces. It will block when there is nothing in the buffer,
and read the entries as they are entered. An EOF happens when
tracing is disabled (tracing_enabled = 0).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Later patches will need to print the same things as the seq output
does. But those outputs will not use the seq utility. This patch
adds a buffer to the iterator, that can be used by either the
seq utility or other output.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch changes the way the CPU trace buffers are handled.
Instead of always starting from the trace page head, the logic
is changed to a producer consumer logic. This allows for the
buffers to be drained while they are alive.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The tests may leave stuff in the buffers. This resets the buffers
after each test is run. If a test fails, it does not reset the
buffer to avoid touching a buffer that is corrupted.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
fix time offset calculations and ordering, plus make code more consistent.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch fixes some bugs to the updating of the max trace that
was caused by implementing the new buffering.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Using raw_local_irq_save/restore confuses lockdep.
It's fine to use the normal ones.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Allocating large buffers for the tracer may fail easily.
This patch converts the buffer from a large ordered allocation
to single pages. It uses the struct page LRU field to link the
pages together.
Later patches may also implement dynamic increasing and decreasing
of the trace buffers.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch adds the latency tracer infrastructure. This patch
does not add anything that will select and turn it on, but will
be used by later patches.
If it were to be compiled, it would add the following files
to the debugfs:
The root tracing directory:
/debugfs/tracing/
This patch also adds the following files:
available_tracers
list of available tracers. Currently no tracers are
available. Looking into this file only shows
"none" which is used to unregister all tracers.
current_tracer
The trace that is currently active. Empty on start up.
To switch to a tracer simply echo one of the tracers that
are listed in available_tracers:
example: (used with later patches)
echo function > /debugfs/tracing/current_tracer
To disable the tracer:
echo disable > /debugfs/tracing/current_tracer
tracing_enabled
echoing "1" into this file starts the ftrace function tracing
(if sysctl kernel.ftrace_enabled=1)
echoing "0" turns it off.
latency_trace
This file is readonly and holds the result of the trace.
trace
This file outputs a easier to read version of the trace.
iter_ctrl
Controls the way the output of traces look.
So far there's two controls:
echoing in "symonly" will only show the kallsyms variables
without the addresses (if kallsyms was configured)
echoing in "verbose" will change the output to show
a lot more data, but not very easy to understand by
humans.
echoing in "nosymonly" turns off symonly.
echoing in "noverbose" turns off verbose.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Ingo Molnar