linux-toradex.git/include/trace/ftrace.h, branch v3.6

perf/trace: Add ability to set a target task for events

2012-07-31T15:02:05+00:00

A few events are interesting not only for a current task.
For example, sched_stat_* events are interesting for a task
which wakes up. For this reason, it will be good if such
events will be delivered to a target task too.

Now a target task can be set by using __perf_task().

The original idea and a draft patch belongs to Peter Zijlstra.

I need these events for profiling sleep times. sched_switch is used for
getting callchains and sched_stat_* is used for getting time periods.
These events are combined in user space, then it can be analyzed by
perf tools.

Inspired-by: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Cc: Steven Rostedt 
Cc: Arun Sharma 
Signed-off-by: Andrew Vagin 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1342016098-213063-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar

tracing/kvm: Use __print_hex() for kvm_emulate_insn tracepoint

2012-06-28T17:52:15+00:00

The kvm_emulate_insn tracepoint used __print_insn()
for printing its instructions. However it makes the
format of the event hard to parse as it reveals TP
internals.

Fortunately, kernel provides __print_hex for almost
same purpose, we can use it instead of open coding
it. The user-space can be changed to parse it later.

That means raw kernel tracing will not be affected
by this change:

 # cd /sys/kernel/debug/tracing/
 # cat events/kvm/kvm_emulate_insn/format
 name: kvm_emulate_insn
 ID: 29
 format:
	...
 print fmt: "%x:%llx:%s (%s)%s", REC->csbase, REC->rip, __print_hex(REC->insn, REC->len), \
 __print_symbolic(REC->flags, { 0, "real" }, { (1 << 0) | (1 << 1), "vm16" }, \
 { (1 << 0), "prot16" }, { (1 << 0) | (1 << 2), "prot32" }, { (1 << 0) | (1 << 3), "prot64" }), \
 REC->failed ? " failed" : ""

 # echo 1 > events/kvm/kvm_emulate_insn/enable
 # cat trace
 # tracer: nop
 #
 # entries-in-buffer/entries-written: 2183/2183   #P:12
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
         qemu-kvm-1782  [002] ...1   140.931636: kvm_emulate_insn: 0:c102fa25:89 10 (prot32)
         qemu-kvm-1781  [004] ...1   140.931637: kvm_emulate_insn: 0:c102fa25:89 10 (prot32)

Link: http://lkml.kernel.org/n/tip-wfw6y3b9ugtey8snaow9nmg5@git.kernel.org
Link: http://lkml.kernel.org/r/1340757701-10711-2-git-send-email-namhyung@kernel.org

Cc: Arnaldo Carvalho de Melo 
Cc: Frederic Weisbecker 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: kvm@vger.kernel.org
Acked-by: Avi Kivity 
Signed-off-by: Namhyung Kim 
Signed-off-by: Steven Rostedt

perf: Fix counter of ftrace events

2011-10-04T09:07:54+00:00

Each event adds some points to its counters. By default it adds 1,
and a number of points may be transmited in event's parameters.

E.g. sched:sched_stat_runtime adds how long process has been running.

But this functionality was broken by v2.6.31-rc5-392-gf413cdb
and now the event's parameters doesn't affect on a number of points.

TP_perf_assign isn't defined, so __perf_count(c) isn't executed and
__count is always equal to 1.

Signed-off-by: Andrew Vagin 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1317052535-1765247-2-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar

tracing: Add __print_symbolic_u64 to avoid warnings on 32bit machine

2011-05-26T02:13:44+00:00

Filesystem, like Btrfs, has some "ULL" macros, and when these macros are passed
to tracepoints'__print_symbolic(), there will be 64->32 truncate WARNINGS during
compiling on 32bit box.

Signed-off-by: Liu Bo 
Link: http://lkml.kernel.org/r/4DACE6E0.7000507@cn.fujitsu.com
Signed-off-by: Steven Rostedt

tracing: Replace trace_event struct array with pointer array

2011-02-03T02:37:13+00:00

Currently the trace_event structures are placed in the _ftrace_events
section, and at link time, the linker makes one large array of all
the trace_event structures. On boot up, this array is read (much like
the initcall sections) and the events are processed.

The problem is that there is no guarantee that gcc will place complex
structures nicely together in an array format. Two structures in the
same file may be placed awkwardly, because gcc has no clue that they
are suppose to be in an array.

A hack was used previous to force the alignment to 4, to pack the
structures together. But this caused alignment issues with other
architectures (sparc).

Instead of packing the structures into an array, the structures' addresses
are now put into the _ftrace_event section. As pointers are always the
natural alignment, gcc should always pack them tightly together
(otherwise initcall, extable, etc would also fail).

By having the pointers to the structures in the section, we can still
iterate the trace_events without causing unnecessary alignment problems
with other architectures, or depending on the current behaviour of
gcc that will likely change in the future just to tick us kernel developers
off a little more.

The _ftrace_event section is also moved into the .init.data section
as it is now only needed at boot up.

Suggested-by: David Miller 
Cc: Mathieu Desnoyers 
Acked-by: David S. Miller 
Signed-off-by: Steven Rostedt

tracing/events: Show real number in array fields

2010-11-19T15:18:47+00:00

Currently we have in something like the sched_switch event:

  field:char prev_comm[TASK_COMM_LEN];	offset:12;	size:16;	signed:1;

When a userspace tool such as perf tries to parse this, the
TASK_COMM_LEN is meaningless. This is done because the TRACE_EVENT() macro
simply uses a #len to show the string of the length. When the length is
an enum, we get a string that means nothing for tools.

By adding a static buffer and a mutex to protect it, we can store the
string into that buffer with snprintf and show the actual number.
Now we get:

  field:char prev_comm[16];       offset:12;      size:16;        signed:1;

Something much more useful.

Signed-off-by: Steven Rostedt

tracing: Allow syscall trace events for non privileged users

2010-11-18T13:37:44+00:00

As for the raw syscalls events, individual syscall events won't
leak system wide information on task bound tracing. Allow non
privileged users to use them in such workflow.

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Thomas Gleixner 
Cc: Steven Rostedt 
Cc: Li Zefan 
Cc: Jason Baron

tracing: New macro to set up initial event flags value

2010-11-18T13:37:42+00:00

This introduces the new TRACE_EVENT_FLAGS() macro in order
to set up initial event flags value.

This macro must simply follow the definition of a trace event
and take the event name and the flag value as parameters:

TRACE_EVENT(my_event, .....
....
);

TRACE_EVENT_FLAGS(my_event, 1)

This will set up 1 as the initial my_event->flags value.

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Thomas Gleixner 
Cc: Steven Rostedt 
Cc: Li Zefan 
Cc: Jason Baron

tracing: Drop cpparg() macro

2010-08-01T23:31:28+00:00

Drop the cpparg() macro that wraps CPP parameters. We already have
the PARAM() macro for that, no need to have several versions.

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Steven Rostedt 
Cc: Li Zefan

tracing: Reduce latency and remove percpu trace_seq

2010-07-21T02:05:34+00:00

__print_flags() and __print_symbolic() use percpu trace_seq:

1) Its memory is allocated at compile time, it wastes memory if we don't use tracing.
2) It is percpu data and it wastes more memory for multi-cpus system.
3) It disables preemption when it executes its core routine
   "trace_seq_printf(s, "%s: ", #call);" and introduces latency.

So we move this trace_seq to struct trace_iterator.

Signed-off-by: Lai Jiangshan 
LKML-Reference: <4C078350.7090106@cn.fujitsu.com>
Signed-off-by: Steven Rostedt