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init, tracing: Add initcall trace events

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Being able to trace the start and stop of initcalls is useful to see where
the timings are an issue. There is already an "initcall_debug" parameter,
but that can cause a large overhead itself, as the printing of the
information may take longer than the initcall functions.

Adding in a start and finish trace event around the initcall functions, as
well as a trace event that records the level of the initcalls, one can get a
much finer measurement of the times and interactions of the initcalls
themselves, as trace events are much lighter than printk()s.

Suggested-by: Abderrahmane Benbachir <abderrahmane.benbachir@polymtl.ca>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2018-03-23 10:18:03 -04:00
parent 8ec8405f08
commit 4ee7c60de8
2 changed files with 73 additions and 0 deletions
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66
include/trace/events/initcall.h Normal file
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@ -0,0 +1,66 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM initcall
#if !defined(_TRACE_INITCALL_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_INITCALL_H
#include <linux/tracepoint.h>
TRACE_EVENT(initcall_level,
TP_PROTO(const char *level),
TP_ARGS(level),
TP_STRUCT__entry(
__string(level, level)
),
TP_fast_assign(
__assign_str(level, level);
),
TP_printk("level=%s", __get_str(level))
);
TRACE_EVENT(initcall_start,
TP_PROTO(initcall_t func),
TP_ARGS(func),
TP_STRUCT__entry(
__field(initcall_t, func)
),
TP_fast_assign(
__entry->func = func;
),
TP_printk("func=%pS", __entry->func)
);
TRACE_EVENT(initcall_finish,
TP_PROTO(initcall_t func, int ret),
TP_ARGS(func, ret),
TP_STRUCT__entry(
__field(initcall_t, func)
__field(int, ret)
),
TP_fast_assign(
__entry->func = func;
__entry->ret = ret;
),
TP_printk("func=%pS ret=%d", __entry->func, __entry->ret)
);
#endif /* if !defined(_TRACE_GPIO_H) || defined(TRACE_HEADER_MULTI_READ) */
/* This part must be outside protection */
#include <trace/define_trace.h>

7
init/main.c
View File

@ -97,6 +97,9 @@
#include <asm/sections.h>
#include <asm/cacheflush.h>
#define CREATE_TRACE_POINTS
#include <trace/events/initcall.h>
static int kernel_init(void *);
extern void init_IRQ(void);
@ -827,10 +830,12 @@ int __init_or_module do_one_initcall(initcall_t fn)
if (initcall_blacklisted(fn))
return -EPERM;
trace_initcall_start(fn);
if (initcall_debug)
ret = do_one_initcall_debug(fn);
else
ret = fn();
trace_initcall_finish(fn, ret);
msgbuf[0] = 0;
@ -895,6 +900,7 @@ static void __init do_initcall_level(int level)
level, level,
NULL, &repair_env_string);
trace_initcall_level(initcall_level_names[level]);
for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
do_one_initcall(*fn);
}
@ -929,6 +935,7 @@ static void __init do_pre_smp_initcalls(void)
{
initcall_t *fn;
trace_initcall_level("early");
for (fn = __initcall_start; fn < __initcall0_start; fn++)
do_one_initcall(*fn);
}