linux-toradex.git/kernel/trace/trace_irqsoff.c, branch v3.0.16

ftrace: Implement separate user function filtering

2011-05-18T19:29:50+00:00

ftrace_ops that are registered to trace functions can now be
agnostic to each other in respect to what functions they trace.
Each ops has their own hash of the functions they want to trace
and a hash to what they do not want to trace. A empty hash for
the functions they want to trace denotes all functions should
be traced that are not in the notrace hash.

Cc: Paul E. McKenney 
Signed-off-by: Steven Rostedt

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

lockdep: Move early boot local IRQ enable/disable status to init/main.c

2011-01-20T12:32:33+00:00

During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized.  During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.

lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available.  While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.

Signed-off-by: Tejun Heo 
Acked-by: Peter Zijlstra 
Acked-by: Pekka Enberg 
Cc: Linus Torvalds 
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar

tracing: Use one prologue for the preempt irqs off tracer function tracers

2010-10-18T14:53:36+00:00

The preempt and irqsoff tracers have three types of function tracers.
Normal function tracer, function graph entry, and function graph return.
Each of these use a complex dance to prevent recursion and whether
to trace the data or not (depending if interrupts are enabled or not).

This patch moves the duplicate code into a single routine, to
prevent future mistakes with modifying duplicate complex code.

Cc: Jiri Olsa 
Signed-off-by: Steven Rostedt

tracing: Make graph related irqs/preemptsoff functions global

2010-10-18T14:53:28+00:00

Move trace_graph_function() and print_graph_headers_flags() functions
to the trace_function_graph.c to be globaly available.

Signed-off-by: Jiri Olsa 
LKML-Reference: <1285243253-7372-3-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt

tracing: Shrink max latency ringbuffer if unnecessary

2010-07-21T14:20:17+00:00

Documentation/trace/ftrace.txt says

  buffer_size_kb:

        This sets or displays the number of kilobytes each CPU
        buffer can hold. The tracer buffers are the same size
        for each CPU. The displayed number is the size of the
        CPU buffer and not total size of all buffers. The
        trace buffers are allocated in pages (blocks of memory
        that the kernel uses for allocation, usually 4 KB in size).
        If the last page allocated has room for more bytes
        than requested, the rest of the page will be used,
        making the actual allocation bigger than requested.
        ( Note, the size may not be a multiple of the page size
          due to buffer management overhead. )

        This can only be updated when the current_tracer
        is set to "nop".

But it's incorrect. currently total memory consumption is
'buffer_size_kb x CPUs x 2'.

Why two times difference is there? because ftrace implicitly allocate
the buffer for max latency too.

That makes sad result when admin want to use large buffer. (If admin
want full logging and makes detail analysis). example, If admin
have 24 CPUs machine and write 200MB to buffer_size_kb, the system
consume ~10GB memory (200MB x 24 x 2). umm.. 5GB memory waste is
usually unacceptable.

Fortunatelly, almost all users don't use max latency feature.
The max latency buffer can be disabled easily.

This patch shrink buffer size of the max latency buffer if
unnecessary.

Signed-off-by: KOSAKI Motohiro 
LKML-Reference: <20100701104554.DA2D.A69D9226@jp.fujitsu.com>
Signed-off-by: Steven Rostedt

tracing: Add graph output support for irqsoff tracer

2010-04-27T16:36:53+00:00

Add function graph output to irqsoff tracer.

The graph output is enabled by setting new 'display-graph' trace option.

Signed-off-by: Jiri Olsa 
LKML-Reference: <1270227683-14631-4-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt

tracing: Add stack trace to irqsoff tracer

2009-12-11T18:19:51+00:00

The irqsoff and friends tracers help in finding causes of latency in the
kernel. The also work with the function tracer to show what was happening
when interrupts or preemption are disabled. But the function tracer has
a bit of an overhead and can cause exagerated readings.

Currently, when tracing with /proc/sys/kernel/ftrace_enabled = 0, where the
function tracer is disabled, the information that is provided can end up
being useless. For example, a 2 and a half millisecond latency only showed:

 # tracer: preemptirqsoff
 #
 # preemptirqsoff latency trace v1.1.5 on 2.6.32
 # --------------------------------------------------------------------
 # latency: 2463 us, #4/4, CPU#2 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
 #    -----------------
 #    | task: -4242 (uid:0 nice:0 policy:0 rt_prio:0)
 #    -----------------
 #  => started at: _spin_lock_irqsave
 #  => ended at:   remove_wait_queue
 #
 #
 #                  _------=> CPU#
 #                 / _-----=> irqs-off
 #                | / _----=> need-resched
 #                || / _---=> hardirq/softirq
 #                ||| / _--=> preempt-depth
 #                |||| /_--=> lock-depth
 #                |||||/     delay
 #  cmd     pid   |||||| time  |   caller
 #     \   /      ||||||   \   |   /
 hackbenc-4242    2d....    0us!: trace_hardirqs_off <-_spin_lock_irqsave
 hackbenc-4242    2...1. 2463us+: _spin_unlock_irqrestore <-remove_wait_queue
 hackbenc-4242    2...1. 2466us : trace_preempt_on <-remove_wait_queue

The above lets us know that hackbench with pid 2463 grabbed a spin lock
somewhere and enabled preemption at remove_wait_queue. This helps a little
but where this actually happened is not informative.

This patch adds the stack dump to the end of the irqsoff tracer. This provides
the following output:

 hackbenc-4242    2d....    0us!: trace_hardirqs_off <-_spin_lock_irqsave
 hackbenc-4242    2...1. 2463us+: _spin_unlock_irqrestore <-remove_wait_queue
 hackbenc-4242    2...1. 2466us : trace_preempt_on <-remove_wait_queue
 hackbenc-4242    2...1. 2467us : 
  => sub_preempt_count
  => _spin_unlock_irqrestore
  => remove_wait_queue
  => free_poll_entry
  => poll_freewait
  => do_sys_poll
  => sys_poll
  => system_call_fastpath

Now we see that the culprit of this latency was the free_poll_entry code.

Signed-off-by: Steven Rostedt

tracing: do not update tracing_max_latency when tracer is stopped

2009-09-13T01:45:17+00:00

The state of the function pair tracing_stop()/tracing_start() is
correctly considered when tracer data are updated. However, the global
and externally accessible variable tracing_max_latency is always updated
- even when tracing is stopped.

The update should only occur, if tracing was not stopped.

Signed-off-by: Carsten Emde 
Signed-off-by: Steven Rostedt

tracing: remove unused local variables in tracer probe functions

2009-09-13T01:44:13+00:00

When the nsecs_to_usecs() conversion in probe_wakeup_sched_switch() and
check_critical_timing() was moved to a later stage in order to avoid
unnecessary computing, it was overlooked to remove the original
variables, assignments and comments..

Signed-off-by: Carsten Emde 
Signed-off-by: Steven Rostedt