linux-stable.git/include/trace/ftrace.h, branch v3.12.2

tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible

2013-08-14T01:06:30+00:00

perf_trace_buf_prepare() + perf_trace_buf_submit(task => NULL)
make no sense if hlist_empty(head). Change perf_trace_##call()
to check ->perf_events beforehand and do nothing if it is empty.

This removes the overhead for tasks without events associated
with them. For example, "perf record -e sched:sched_switch -p1"
attaches the counter(s) to the single task, but every task in
system will do perf_trace_buf_prepare/submit() just to realize
that it was not attached to this event.

However, we can only do this if __task == NULL, so we also add
the __builtin_constant_p(__task) check.

With this patch "perf bench sched pipe" shows approximately 4%
improvement when "perf record -p1" runs in parallel, many thanks
to Steven for the testing.

Link: http://lkml.kernel.org/r/20130806160847.GA2746@redhat.com

Tested-by: David Ahern 
Acked-by: Peter Zijlstra 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

tracing/perf: Reimplement TP_perf_assign() logic

2013-08-14T01:05:57+00:00

The next patch tries to avoid the costly perf_trace_buf_* calls
when possible but there is a problem. We can only do this if
__task == NULL, perf_tp_event(task != NULL) has the additional
code for this case.

Unfortunately, TP_perf_assign/__perf_xxx which changes the default
values of __count/__task variables for perf_trace_buf_submit() is
called "too late", after we already did perf_trace_buf_prepare(),
and the optimization above can't work.

So this patch simply embeds __perf_xxx() into TP_ARGS(), this way
DECLARE_EVENT_CLASS() can use the result of assignments hidden in
"args" right after ftrace_get_offsets_##call() which is mostly
trivial. This allows us to have the fast-path "__task != NULL"
check at the start, see the next patch.

Link: http://lkml.kernel.org/r/20130806160844.GA2739@redhat.com

Tested-by: David Ahern 
Acked-by: Peter Zijlstra 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

tracing/perf: Expand TRACE_EVENT(sched_stat_runtime)

2013-08-14T01:05:12+00:00

To simplify the review of the next patches:

1. We are going to reimplent __perf_task/counter and embedd them
   into TP_ARGS(). expand TRACE_EVENT(sched_stat_runtime) into
   DECLARE_EVENT_CLASS() + DEFINE_EVENT(), this way they can use
   different TP_ARGS's.

2. Change perf_trace_##call() macro to do perf_fetch_caller_regs()
   right before perf_trace_buf_prepare().

   This way it evaluates TP_ARGS() asap, the next patch explores
   this fact.

   Note: after 87f44bbc perf_trace_buf_prepare() doesn't need
   "struct pt_regs *regs", perhaps it makes sense to remove this
   argument. And perhaps we can teach perf_trace_buf_submit()
   to accept regs == NULL and do fetch_caller_regs(CALLER_ADDR1)
   in this case.

3. Cosmetic, but the typecast from "void*" buys nothing. It just
   adds the noise, remove it.

Link: http://lkml.kernel.org/r/20130806160841.GA2736@redhat.com

Acked-by: Peter Zijlstra 
Tested-by: David Ahern 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare()

2013-07-19T01:31:28+00:00

Every perf_trace_buf_prepare() caller does
WARN_ONCE(size > PERF_MAX_TRACE_SIZE, message) and "message" is
almost the same.

Shift this WARN_ONCE() into perf_trace_buf_prepare(). This changes
the meaning of _ONCE, but I think this is fine.

	- 4947014 2932448 10104832  17984294  1126b26 vmlinux
	+ 4948422 2932448 10104832  17985702  11270a6 vmlinux

on my build.

Link: http://lkml.kernel.org/r/20130617170211.GA19813@redhat.com

Acked-by: Peter Zijlstra 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

tracing: Add DEFINE_EVENT_FN() macro

2013-06-21T05:24:32+00:00

Each TRACE_EVENT() adds several helper functions. If two or more trace events
share the same structure and print format, they can also share most of these
helper functions and save a lot of space from duplicate code. This is why the
DECLARE_EVENT_CLASS() and DEFINE_EVENT() were created.

Some events require a trigger to be called at registering and unregistering of
the event and to do so they use TRACE_EVENT_FN().

If multiple events require a trigger, they currently have no choice but to use
TRACE_EVENT_FN() as there's no DEFINE_EVENT_FN() available. This unfortunately
causes a lot of wasted duplicate code created.

By adding a DEFINE_EVENT_FN(), these events can still use a
DECLARE_EVENT_CLASS() and then define their own triggers.

Signed-off-by: Steven Rostedt 
Link: http://lkml.kernel.org/r/51C3236C.8030508@hds.com
Signed-off-by: Seiji Aguchi 
Signed-off-by: H. Peter Anvin

tracing: Remove obsolete macro guard _TRACE_PROFILE_INIT

2013-04-13T03:02:33+00:00

The macro _TRACE_PROFILE_INIT was removed a long time ago,
but an "#undef" guard was left behind. Remove it.

Link: http://lkml.kernel.org/r/514684EE.6000805@huawei.com

Signed-off-by: zhangwei(Jovi) 
Signed-off-by: Steven Rostedt

tracing: Add a way to soft disable trace events

2013-03-15T04:36:03+00:00

In order to let triggers enable or disable events, we need a 'soft'
method for doing so. For example, if a function probe is added that
lets a user enable or disable events when a function is called, that
change must be done without taking locks or a mutex, and definitely
it can't sleep. But the full enabling of a tracepoint is expensive.

By adding a 'SOFT_DISABLE' flag, and converting the flags to be updated
without the protection of a mutex (using set/clear_bit()), this soft
disable flag can be used to allow critical sections to enable or disable
events from being traced (after the event has been placed into "SOFT_MODE").

Some caveats though: The comm recorder (to map pids with a comm) can not
be soft disabled (yet). If you disable an event with with a "soft"
disable and wait a while before reading the trace, the comm cache may be
replaced and you'll get a bunch of <...> for comms in the trace.

Reading the "enable" file for an event that is disabled will now give
you "0*" where the '*' denotes that the tracepoint is still active but
the event itself is "disabled".

[ fixed _BIT used in & operation : thanks to Dan Carpenter and smatch ]

Cc: Dan Carpenter 
Cc: Tom Zanussi 
Signed-off-by: Steven Rostedt

tracing: Fix some section mismatch warnings

2013-03-15T04:34:54+00:00

As we've added __init annotation to field-defining functions, we should
add __refdata annotation to event_call variables, which reference those
functions.

Link: http://lkml.kernel.org/r/51343C1F.2050502@huawei.com

Reported-by: Fengguang Wu 
Signed-off-by: Li Zefan 
Signed-off-by: Steven Rostedt

tracing: Annotate event field-defining functions with __init

2013-03-15T04:34:51+00:00

Those functions are called either during kernel boot or module init.

Before:

$ dmesg | grep 'Freeing unused kernel memory'
Freeing unused kernel memory: 1208k freed
Freeing unused kernel memory: 1360k freed
Freeing unused kernel memory: 1960k freed

After:

$ dmesg | grep 'Freeing unused kernel memory'
Freeing unused kernel memory: 1236k freed
Freeing unused kernel memory: 1388k freed
Freeing unused kernel memory: 1960k freed

Link: http://lkml.kernel.org/r/5125877D.5000201@huawei.com

Signed-off-by: Li Zefan 
Signed-off-by: Steven Rostedt

tracing: Add a helper function for event print functions

2013-03-15T04:34:51+00:00

Move duplicate code in event print functions to a helper function.

This shrinks the size of the kernel by ~13K.

   text    data     bss     dec     hex filename
6596137 1743966 10138672        18478775        119f6b7 vmlinux.o.old
6583002 1743849 10138672        18465523        119c2f3 vmlinux.o.new

Link: http://lkml.kernel.org/r/51258746.2060304@huawei.com

Signed-off-by: Li Zefan 
Signed-off-by: Steven Rostedt