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ftrace: add tracer called branch 

Impact: added new branch tracer

Currently the tracing of branch profiling (unlikelys and likelys hit)
is only activated by the iter_ctrl. This patch adds a tracer called
"branch" that will just trace the branch profiling. The advantage
of adding this tracer is that it can be added to the ftrace selftests
on startup.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-11-12 15:24:24 -05:00 committed by Ingo Molnar
parent 9f029e83e9
commit 80e5ea4506
3 changed files with 67 additions and 0 deletions
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2
kernel/trace/trace.h
View File

@ -420,6 +420,8 @@ extern int trace_selftest_startup_sched_switch(struct tracer *trace,
struct trace_array *tr);
extern int trace_selftest_startup_sysprof(struct tracer *trace,
struct trace_array *tr);
extern int trace_selftest_startup_branch(struct tracer *trace,
struct trace_array *tr);
#endif /* CONFIG_FTRACE_STARTUP_TEST */
extern void *head_page(struct trace_array_cpu *data);

23
kernel/trace/trace_selftest.c
View File

@ -13,6 +13,7 @@ static inline int trace_valid_entry(struct trace_entry *entry)
case TRACE_STACK:
case TRACE_PRINT:
case TRACE_SPECIAL:
case TRACE_BRANCH:
return 1;
}
return 0;
@ -544,3 +545,25 @@ trace_selftest_startup_sysprof(struct tracer *trace, struct trace_array *tr)
return ret;
}
#endif /* CONFIG_SYSPROF_TRACER */
#ifdef CONFIG_BRANCH_TRACER
int
trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr)
{
unsigned long count;
int ret;
/* start the tracing */
trace->init(tr);
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
tracing_stop();
/* check the trace buffer */
ret = trace_test_buffer(tr, &count);
trace->reset(tr);
tracing_start();
return ret;
}
#endif /* CONFIG_BRANCH_TRACER */

42
kernel/trace/trace_unlikely.c
View File

@ -114,6 +114,48 @@ void disable_branch_tracing(void)
out_unlock:
mutex_unlock(&branch_tracing_mutex);
}
static void start_branch_trace(struct trace_array *tr)
{
enable_branch_tracing(tr);
}
static void stop_branch_trace(struct trace_array *tr)
{
disable_branch_tracing();
}
static void branch_trace_init(struct trace_array *tr)
{
int cpu;
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
start_branch_trace(tr);
}
static void branch_trace_reset(struct trace_array *tr)
{
stop_branch_trace(tr);
}
struct tracer branch_trace __read_mostly =
{
.name = "branch",
.init = branch_trace_init,
.reset = branch_trace_reset,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_branch,
#endif
};
__init static int init_branch_trace(void)
{
return register_tracer(&branch_trace);
}
device_initcall(init_branch_trace);
#else
static inline
void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)