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tracing/fastboot: Enable boot tracing only during initcalls

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Impact: modify boot tracer

We used to disable the initcall tracing at a specified time (IE: end
of builtin initcalls). But we don't need it anymore. It will be
stopped when initcalls are finished.

However we want two things:

_Start this tracing only after pre-smp initcalls are finished.

_Since we are planning to trace sched_switches at the same time, we
want to enable them only during the initcall execution.

For this purpose, this patch introduce two functions to enable/disable
the sched_switch tracing during boot.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2008-10-31 12:57:20 +01:00 • committed by Ingo Molnar
parent 7a895f53cd
commit 71566a0d16
3 changed files with 41 additions and 15 deletions
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24
include/linux/ftrace.h
View file

@ -234,6 +234,11 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { }
#endif
/*
* Structure which defines the trace of an initcall.
* You don't have to fill the func field since it is
* only used internally by the tracer.
*/
struct boot_trace {
pid_t caller;
char func[KSYM_NAME_LEN];
@ -244,13 +249,28 @@ struct boot_trace {
};
#ifdef CONFIG_BOOT_TRACER
/* Append the trace on the ring-buffer */
extern void trace_boot(struct boot_trace *it, initcall_t fn);
/* Tells the tracer that smp_pre_initcall is finished.
* So we can start the tracing
*/
extern void start_boot_trace(void);
extern void stop_boot_trace(void);
/* Resume the tracing of other necessary events
* such as sched switches
*/
extern void enable_boot_trace(void);
/* Suspend this tracing. Actually, only sched_switches tracing have
* to be suspended. Initcalls doesn't need it.)
*/
extern void disable_boot_trace(void);
#else
static inline void trace_boot(struct boot_trace *it, initcall_t fn) { }
static inline void start_boot_trace(void) { }
static inline void stop_boot_trace(void) { }
static inline void enable_boot_trace(void) { }
static inline void disable_boot_trace(void) { }
#endif