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Subject[PATCH 3/5][RFC] tracing: adding function timings to function profiler
From: Steven Rostedt <srostedt@redhat.com>

If the function graph trace is enabled, the function profiler will
use it to take the timing of the functions.

cat /debug/tracing/trace_stat/functions

Function Hit Time
-------- --- ----
mwait_idle 127 183028.4 us
schedule 26 151997.7 us
__schedule 31 151975.1 us
sys_wait4 2 74080.53 us
do_wait 2 74077.80 us
sys_newlstat 138 39929.16 us
do_path_lookup 179 39845.79 us
vfs_lstat_fd 138 39761.97 us
user_path_at 153 39469.58 us
path_walk 179 39435.76 us
__link_path_walk 189 39143.73 us
[...]
Note the times are skewed due to the function graph tracer not taking
into account schedules.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/trace/ftrace.c | 93 ++++++++++++++++++++++++++++++++--
kernel/trace/trace.c | 11 ----
kernel/trace/trace.h | 3 +-
kernel/trace/trace_functions_graph.c | 17 +++++-
kernel/trace/trace_output.c | 10 ++++
kernel/trace/trace_output.h | 2 +
6 files changed, 117 insertions(+), 19 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 24dac44..a9ccd71 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -33,7 +33,7 @@

#include <asm/ftrace.h>

-#include "trace.h"
+#include "trace_output.h"
#include "trace_stat.h"

#define FTRACE_WARN_ON(cond) \
@@ -246,6 +246,9 @@ struct ftrace_profile {
struct hlist_node node;
unsigned long ip;
unsigned long counter;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ unsigned long long time;
+#endif
};

struct ftrace_profile_page {
@@ -303,6 +306,22 @@ static void *function_stat_start(struct tracer_stat *trace)
return function_stat_next(&profile_pages_start->records[0], 0);
}

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/* function graph compares on total time */
+static int function_stat_cmp(void *p1, void *p2)
+{
+ struct ftrace_profile *a = p1;
+ struct ftrace_profile *b = p2;
+
+ if (a->time < b->time)
+ return -1;
+ if (a->time > b->time)
+ return 1;
+ else
+ return 0;
+}
+#else
+/* not function graph compares against hits */
static int function_stat_cmp(void *p1, void *p2)
{
struct ftrace_profile *a = p1;
@@ -315,11 +334,17 @@ static int function_stat_cmp(void *p1, void *p2)
else
return 0;
}
+#endif

static int function_stat_headers(struct seq_file *m)
{
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ seq_printf(m, " Function Hit Time\n"
+ " -------- --- ----\n");
+#else
seq_printf(m, " Function Hit\n"
" -------- ---\n");
+#endif
return 0;
}

@@ -327,10 +352,25 @@ static int function_stat_show(struct seq_file *m, void *v)
{
struct ftrace_profile *rec = v;
char str[KSYM_SYMBOL_LEN];
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ static struct trace_seq s;
+ static DEFINE_MUTEX(mutex);
+
+ mutex_lock(&mutex);
+ trace_seq_init(&s);
+ trace_print_graph_duration(rec->time, &s);
+#endif

kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+ seq_printf(m, " %-30.30s %10lu", str, rec->counter);
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ seq_printf(m, " ");
+ trace_print_seq(m, &s);
+ mutex_unlock(&mutex);
+#endif
+ seq_putc(m, '\n');

- seq_printf(m, " %-30.30s %10lu\n", str, rec->counter);
return 0;
}

@@ -534,11 +574,52 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
local_irq_restore(flags);
}

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static int profile_graph_entry(struct ftrace_graph_ent *trace)
+{
+ function_profile_call(trace->func, 0);
+ return 1;
+}
+
+static void profile_graph_return(struct ftrace_graph_ret *trace)
+{
+ unsigned long flags;
+ struct ftrace_profile *rec;
+
+ local_irq_save(flags);
+ rec = ftrace_find_profiled_func(trace->func);
+ if (rec)
+ rec->time += trace->rettime - trace->calltime;
+ local_irq_restore(flags);
+}
+
+static int register_ftrace_profiler(void)
+{
+ return register_ftrace_graph(&profile_graph_return,
+ &profile_graph_entry);
+}
+
+static void unregister_ftrace_profiler(void)
+{
+ unregister_ftrace_graph();
+}
+#else
static struct ftrace_ops ftrace_profile_ops __read_mostly =
{
.func = function_profile_call,
};

+static int register_ftrace_profiler(void)
+{
+ return register_ftrace_function(&ftrace_profile_ops);
+}
+
+static void unregister_ftrace_profiler(void)
+{
+ unregister_ftrace_function(&ftrace_profile_ops);
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
static ssize_t
ftrace_profile_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@@ -570,11 +651,15 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
goto out;
}

- register_ftrace_function(&ftrace_profile_ops);
+ ret = register_ftrace_profiler();
+ if (ret < 0) {
+ cnt = ret;
+ goto out;
+ }
ftrace_profile_enabled = 1;
} else {
ftrace_profile_enabled = 0;
- unregister_ftrace_function(&ftrace_profile_ops);
+ unregister_ftrace_profiler();
}
}
out:
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 67c6a21..821bf49 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -402,17 +402,6 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
return cnt;
}

-static void
-trace_print_seq(struct seq_file *m, struct trace_seq *s)
-{
- int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
-
- s->buffer[len] = 0;
- seq_puts(m, s->buffer);
-
- trace_seq_init(s);
-}
-
/**
* update_max_tr - snapshot all trace buffers from global_trace to max_tr
* @tr: tracer
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d7410bb..c66ca3b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -605,6 +605,8 @@ extern unsigned long trace_flags;
/* Standard output formatting function used for function return traces */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
extern enum print_line_t print_graph_function(struct trace_iterator *iter);
+extern enum print_line_t
+trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);

#ifdef CONFIG_DYNAMIC_FTRACE
/* TODO: make this variable */
@@ -636,7 +638,6 @@ static inline int ftrace_graph_addr(unsigned long addr)
return 1;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
-
#else /* CONFIG_FUNCTION_GRAPH_TRACER */
static inline enum print_line_t
print_graph_function(struct trace_iterator *iter)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index d28687e..85bba0f 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -426,8 +426,8 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
return TRACE_TYPE_HANDLED;
}

-static enum print_line_t
-print_graph_duration(unsigned long long duration, struct trace_seq *s)
+enum print_line_t
+trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
{
unsigned long nsecs_rem = do_div(duration, 1000);
/* log10(ULONG_MAX) + '\0' */
@@ -464,12 +464,23 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s)
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
+ return TRACE_TYPE_HANDLED;
+}
+
+static enum print_line_t
+print_graph_duration(unsigned long long duration, struct trace_seq *s)
+{
+ int ret;
+
+ ret = trace_print_graph_duration(duration, s);
+ if (ret != TRACE_TYPE_HANDLED)
+ return ret;

ret = trace_seq_printf(s, "| ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
- return TRACE_TYPE_HANDLED;

+ return TRACE_TYPE_HANDLED;
}

/* Case of a leaf function on its call entry */
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 19261fd..a3b6e3f 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -19,6 +19,16 @@ static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;

static int next_event_type = __TRACE_LAST_TYPE + 1;

+void trace_print_seq(struct seq_file *m, struct trace_seq *s)
+{
+ int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
+
+ s->buffer[len] = 0;
+ seq_puts(m, s->buffer);
+
+ trace_seq_init(s);
+}
+
enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
index 35c422f..1eac297 100644
--- a/kernel/trace/trace_output.h
+++ b/kernel/trace/trace_output.h
@@ -20,6 +20,8 @@ trace_print_bprintk_msg_only(struct trace_iterator *iter);
extern enum print_line_t
trace_print_printk_msg_only(struct trace_iterator *iter);

+extern void trace_print_seq(struct seq_file *m, struct trace_seq *s);
+
extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int
--
1.6.2
--


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