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alistair23-linux/kernel/trace/trace_functions_graph.c
Frederic Weisbecker 1a056155ed tracing/function-graph-tracer: adjustments of the trace informations 
Impact: increase the visual qualities of the call-graph-tracer output

This patch applies various trace output formatting changes:

 - CPU is now a decimal number, followed by a parenthesis.

 - Overhead is now on the second column (gives a good visibility)

 - Cost is now on the third column, can't exceed 9999.99 us. It is
   followed by a virtual line based on a "|" character.

 - Functions calls are now the last column on the right. This way, we
   haven't dynamic column (which flow is harder to follow) on its right.

 - CPU and Overhead have their own option flag. They are default-on but you
   can disable them easily:

      echo nofuncgraph-cpu > trace_options
      echo nofuncgraph-overhead > trace_options

TODO:

_ Refactoring of the thread switch output.
_ Give a default-off option to output the thread and its pid on each row.
_ Provide headers
_ ....

Here is an example of the new trace style:

0)           |             mutex_unlock() {
0)      0.639 us |           __mutex_unlock_slowpath();
0)      1.607 us |         }
0)           |             remove_wait_queue() {
0)      0.616 us |           _spin_lock_irqsave();
0)      0.616 us |           _spin_unlock_irqrestore();
0)      2.779 us |         }
0)      0.495 us |         n_tty_set_room();
0) ! 9999.999 us |       }
0)           |           tty_ldisc_deref() {
0)      0.615 us |         _spin_lock_irqsave();
0)      0.616 us |         _spin_unlock_irqrestore();
0)      2.793 us |       }
0)           |           current_fs_time() {
0)      0.488 us |         current_kernel_time();
0)      0.495 us |         timespec_trunc();
0)      2.486 us |       }
0) ! 9999.999 us |     }
0) ! 9999.999 us |   }
0) ! 9999.999 us | }
0)           |     sys_read() {
0)      0.796 us |   fget_light();
0)           |       vfs_read() {
0)           |         rw_verify_area() {
0)           |           security_file_permission() {
0)      0.488 us |         cap_file_permission();
0)      1.720 us |       }
0)      3.  4 us |     }
0)           |         tty_read() {
0)      0.488 us |       tty_paranoia_check();
0)           |           tty_ldisc_ref_wait() {
0)           |             tty_ldisc_try() {
0)      0.615 us |           _spin_lock_irqsave();
0)      0.615 us |           _spin_unlock_irqrestore();
0)      5.436 us |         }
0)      6.427 us |       }

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-28 09:45:04 +01:00

370 lines
8.2 KiB
C
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/*
*
* Function graph tracer.
* Copyright (c) 2008 Frederic Weisbecker <fweisbec@gmail.com>
* Mostly borrowed from function tracer which
* is Copyright (c) Steven Rostedt <srostedt@redhat.com>
*
*/
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/fs.h>
#include "trace.h"
#define TRACE_GRAPH_INDENT 2
/* Flag options */
#define TRACE_GRAPH_PRINT_OVERRUN 0x1
#define TRACE_GRAPH_PRINT_CPU 0x2
#define TRACE_GRAPH_PRINT_OVERHEAD 0x4
static struct tracer_opt trace_opts[] = {
/* Display overruns ? */
{ TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
/* Display CPU ? */
{ TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
/* Display Overhead ? */
{ TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
{ } /* Empty entry */
};
static struct tracer_flags tracer_flags = {
/* Don't display overruns by default */
.val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD,
.opts = trace_opts
};
/* pid on the last trace processed */
static pid_t last_pid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
static int graph_trace_init(struct trace_array *tr)
{
int cpu, ret;
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
ret = register_ftrace_graph(&trace_graph_return,
&trace_graph_entry);
if (ret)
return ret;
tracing_start_cmdline_record();
return 0;
}
static void graph_trace_reset(struct trace_array *tr)
{
tracing_stop_cmdline_record();
unregister_ftrace_graph();
}
static inline int log10_cpu(int nb)
{
if (nb / 100)
return 3;
if (nb / 10)
return 2;
return 1;
}
static enum print_line_t
print_graph_cpu(struct trace_seq *s, int cpu)
{
int i;
int ret;
int log10_this = log10_cpu(cpu);
int log10_all = log10_cpu(cpus_weight_nr(cpu_online_map));
for (i = 0; i < log10_all - log10_this; i++) {
ret = trace_seq_printf(s, " ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = trace_seq_printf(s, "%d) ", cpu);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
/* If the pid changed since the last trace, output this event */
static int verif_pid(struct trace_seq *s, pid_t pid, int cpu)
{
char *comm;
if (last_pid[cpu] != -1 && last_pid[cpu] == pid)
return 1;
last_pid[cpu] = pid;
comm = trace_find_cmdline(pid);
return trace_seq_printf(s, "\n------------8<---------- thread %s-%d"
" ------------8<----------\n\n",
cpu, comm, pid);
}
static bool
trace_branch_is_leaf(struct trace_iterator *iter,
struct ftrace_graph_ent_entry *curr)
{
struct ring_buffer_iter *ring_iter;
struct ring_buffer_event *event;
struct ftrace_graph_ret_entry *next;
ring_iter = iter->buffer_iter[iter->cpu];
if (!ring_iter)
return false;
event = ring_buffer_iter_peek(ring_iter, NULL);
if (!event)
return false;
next = ring_buffer_event_data(event);
if (next->ent.type != TRACE_GRAPH_RET)
return false;
if (curr->ent.pid != next->ent.pid ||
curr->graph_ent.func != next->ret.func)
return false;
return true;
}
static inline int
print_graph_duration(unsigned long long duration, struct trace_seq *s)
{
unsigned long nsecs_rem = do_div(duration, 1000);
return trace_seq_printf(s, "%4llu.%3lu us | ", duration, nsecs_rem);
}
/* Signal a overhead of time execution to the output */
static int
print_graph_overhead(unsigned long long duration, struct trace_seq *s)
{
/* Duration exceeded 100 msecs */
if (duration > 100000ULL)
return trace_seq_printf(s, "! ");
/* Duration exceeded 10 msecs */
if (duration > 10000ULL)
return trace_seq_printf(s, "+ ");
return trace_seq_printf(s, " ");
}
/* Case of a leaf function on its call entry */
static enum print_line_t
print_graph_entry_leaf(struct trace_iterator *iter,
struct ftrace_graph_ent_entry *entry, struct trace_seq *s)
{
struct ftrace_graph_ret_entry *ret_entry;
struct ftrace_graph_ret *graph_ret;
struct ring_buffer_event *event;
struct ftrace_graph_ent *call;
unsigned long long duration;
int ret;
int i;
event = ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
ret_entry = ring_buffer_event_data(event);
graph_ret = &ret_entry->ret;
call = &entry->graph_ent;
duration = graph_ret->rettime - graph_ret->calltime;
/* Must not exceed 8 characters: 9999.999 us */
if (duration > 10000000ULL)
duration = 9999999ULL;
/* Overhead */
if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
ret = print_graph_overhead(duration, s);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
/* Duration */
ret = print_graph_duration(duration, s);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
/* Function */
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
ret = trace_seq_printf(s, " ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = seq_print_ip_sym(s, call->func, 0);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, "();\n");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
static enum print_line_t
print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
struct trace_seq *s)
{
int i;
int ret;
struct ftrace_graph_ent *call = &entry->graph_ent;
/* No overhead */
if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
ret = trace_seq_printf(s, " ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
/* No time */
ret = trace_seq_printf(s, " | ");
/* Function */
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
ret = trace_seq_printf(s, " ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = seq_print_ip_sym(s, call->func, 0);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, "() {\n");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
static enum print_line_t
print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
struct trace_iterator *iter, int cpu)
{
int ret;
struct trace_entry *ent = iter->ent;
/* Pid */
if (!verif_pid(s, ent->pid, cpu))
return TRACE_TYPE_PARTIAL_LINE;
/* Cpu */
if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
ret = print_graph_cpu(s, cpu);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
if (trace_branch_is_leaf(iter, field))
return print_graph_entry_leaf(iter, field, s);
else
return print_graph_entry_nested(field, s);
}
static enum print_line_t
print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
struct trace_entry *ent, int cpu)
{
int i;
int ret;
unsigned long long duration = trace->rettime - trace->calltime;
/* Must not exceed 8 characters: xxxx.yyy us */
if (duration > 10000000ULL)
duration = 9999999ULL;
/* Pid */
if (!verif_pid(s, ent->pid, cpu))
return TRACE_TYPE_PARTIAL_LINE;
/* Cpu */
if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
ret = print_graph_cpu(s, cpu);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
/* Overhead */
if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
ret = print_graph_overhead(duration, s);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
/* Duration */
ret = print_graph_duration(duration, s);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
/* Closing brace */
for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
ret = trace_seq_printf(s, " ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = trace_seq_printf(s, "}\n");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
/* Overrun */
if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
ret = trace_seq_printf(s, " (Overruns: %lu)\n",
trace->overrun);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
return TRACE_TYPE_HANDLED;
}
enum print_line_t
print_graph_function(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry = iter->ent;
switch (entry->type) {
case TRACE_GRAPH_ENT: {
struct ftrace_graph_ent_entry *field;
trace_assign_type(field, entry);
return print_graph_entry(field, s, iter,
iter->cpu);
}
case TRACE_GRAPH_RET: {
struct ftrace_graph_ret_entry *field;
trace_assign_type(field, entry);
return print_graph_return(&field->ret, s, entry, iter->cpu);
}
default:
return TRACE_TYPE_UNHANDLED;
}
}
static struct tracer graph_trace __read_mostly = {
.name = "function_graph",
.init = graph_trace_init,
.reset = graph_trace_reset,
.print_line = print_graph_function,
.flags = &tracer_flags,
};
static __init int init_graph_trace(void)
{
return register_tracer(&graph_trace);
}
device_initcall(init_graph_trace);
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