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tracing/fastboot: Enable boot tracing only during initcalls 

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

4
init/main.c
View File

@ -711,6 +711,7 @@ int do_one_initcall(initcall_t fn)
it.caller = task_pid_nr(current);
printk("calling %pF @ %i\n", fn, it.caller);
it.calltime = ktime_get();
enable_boot_trace();
}
it.result = fn();
@ -722,6 +723,7 @@ int do_one_initcall(initcall_t fn)
printk("initcall %pF returned %d after %Ld usecs\n", fn,
it.result, it.duration);
trace_boot(&it, fn);
disable_boot_trace();
}
msgbuf[0] = 0;
@ -882,7 +884,7 @@ static int __init kernel_init(void * unused)
* we're essentially up and running. Get rid of the
* initmem segments and start the user-mode stuff..
*/
stop_boot_trace();
init_post();
return 0;
}

28
kernel/trace/trace_boot.c
View File

@ -13,23 +13,29 @@
#include "trace.h"
static struct trace_array *boot_trace;
static int trace_boot_enabled;
static bool pre_initcalls_finished;
/* Should be started after do_pre_smp_initcalls() in init/main.c */
/* Tells the boot tracer that the pre_smp_initcalls are finished.
* So we are ready .
* It doesn't enable sched events tracing however.
* You have to call enable_boot_trace to do so.
*/
void start_boot_trace(void)
{
trace_boot_enabled = 1;
pre_initcalls_finished = true;
}
void stop_boot_trace(void)
void enable_boot_trace(void)
{
}
void disable_boot_trace(void)
{
trace_boot_enabled = 0;
}
void reset_boot_trace(struct trace_array *tr)
{
stop_boot_trace();
disable_boot_trace();
}
static void boot_trace_init(struct trace_array *tr)
@ -37,8 +43,6 @@ static void boot_trace_init(struct trace_array *tr)
int cpu;
boot_trace = tr;
trace_boot_enabled = 0;
for_each_cpu_mask(cpu, cpu_possible_map)
tracing_reset(tr, cpu);
}
@ -46,9 +50,9 @@ static void boot_trace_init(struct trace_array *tr)
static void boot_trace_ctrl_update(struct trace_array *tr)
{
if (tr->ctrl)
start_boot_trace();
enable_boot_trace();
else
stop_boot_trace();
disable_boot_trace();
}
static enum print_line_t initcall_print_line(struct trace_iterator *iter)
@ -99,7 +103,7 @@ void trace_boot(struct boot_trace *it, initcall_t fn)
unsigned long irq_flags;
struct trace_array *tr = boot_trace;
if (!trace_boot_enabled)
if (!pre_initcalls_finished)
return;
/* Get its name now since this function could