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tracing/branch-tracer: adapt to the stat tracing API 

Impact: refactor the branch tracer

This patch adapts the branch tracer to the tracing API.

This is a proof of concept because the branch tracer implements two
"stat tracing" that were split in two files.

So I added an option to the branch tracer: stat_all_branch.
If it is set, then trace_stat will output all of the branches
entries stats. Otherwise, it will print the annotated branches.

Its is a kind of quick trick, waiting for a better solution.

By default, the annotated branches stat are sorted by incorrect branch
prediction percentage.

Ie:

 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
       0        1 100 native_smp_prepare_cpus        smpboot.c            1228
       0        1 100 hpet_rtc_timer_reinit          hpet.c               1057
       0    18032 100 sched_info_queued              sched_stats.h        223
       0      684 100 yield_task_fair                sched_fair.c         984
       0      282 100 pre_schedule_rt                sched_rt.c           1263
       0    13414 100 sched_info_dequeued            sched_stats.h        178
       0    21724 100 sched_info_switch              sched_stats.h        270
       0        1 100 get_signal_to_deliver          signal.c             1820
       0        8 100 __cancel_work_timer            workqueue.c          560
       0      212 100 verify_export_symbols          module.c             1509
       0       17 100 __rmqueue_fallback             page_alloc.c         793
       0       43 100 clear_page_mlock               internal.h           129
       0      124 100 try_to_unmap_anon              rmap.c               1021
       0       53 100 try_to_unmap_anon              rmap.c               1013
       0        6 100 vma_address                    rmap.c               232
       0     3301 100 try_to_unmap_file              rmap.c               1082
       0      466 100 try_to_unmap_file              rmap.c               1077
       0        1 100 mem_cgroup_create              memcontrol.c         1090
       0        3 100 inotify_find_update_watch      inotify.c            726
       2    30163  99 perf_counter_task_sched_out    perf_counter.c       385
       1     2935  99 percpu_free                    allocpercpu.c        138
    1544   297672  99 dentry_lru_del_init            dcache.c             153
       8     1074  99 input_pass_event               input.c              86
    1390    76781  98 mapping_unevictable            pagemap.h            50
     280     6665  95 pick_next_task_rt              sched_rt.c           889
     750     4826  86 next_pidmap                    pid.c                194
       2        8  80 blocking_notifier_chain_regist notifier.c           220
      36      130  78 ioremap_pte_range              ioremap.c            22
    1093     3247  74 IS_ERR                         err.h                34
    1023     2908  73 sched_slice                    sched_fair.c         445
      22       60  73 disk_put_part                  genhd.h              206
[...]

It enables a developer to quickly address the source of incorrect branch
predictions.  Note that this sorting would be better with a second sort on
the number of incorrect predictions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2008-12-27 23:25:38 +01:00 committed by Ingo Molnar
parent dbd0b4b330
commit e302cf3f96
1 changed files with 159 additions and 143 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

302
kernel/trace/trace_branch.c
View File

@ -18,10 +18,13 @@
#include "trace.h"
#include "trace_output.h"
static struct tracer branch_trace;
#ifdef CONFIG_BRANCH_TRACER
static int branch_tracing_enabled __read_mostly;
static DEFINE_MUTEX(branch_tracing_mutex);
static struct trace_array *branch_tracer;
static void
@ -178,6 +181,7 @@ trace_branch_print(struct trace_seq *s, struct trace_entry *entry, int flags)
return 0;
}
static struct trace_event trace_branch_event = {
.type = TRACE_BRANCH,
.trace = trace_branch_print,
@ -187,30 +191,6 @@ static struct trace_event trace_branch_event = {
.binary = trace_nop_print,
};
struct tracer branch_trace __read_mostly =
{
.name = "branch",
.init = branch_trace_init,
.reset = branch_trace_reset,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_branch,
#endif
};
__init static int init_branch_trace(void)
{
int ret;
ret = register_ftrace_event(&trace_branch_event);
if (!ret) {
printk(KERN_WARNING "Warning: could not register branch events\n");
return 1;
}
return register_tracer(&branch_trace);
}
device_initcall(init_branch_trace);
#else
static inline
void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
@ -236,65 +216,38 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
}
EXPORT_SYMBOL(ftrace_likely_update);
struct ftrace_pointer {
void *start;
void *stop;
int hit;
};
extern unsigned long __start_annotated_branch_profile[];
extern unsigned long __stop_annotated_branch_profile[];
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
static int annotated_branch_stat_headers(struct seq_file *m)
{
const struct ftrace_pointer *f = m->private;
struct ftrace_branch_data *p = v;
(*pos)++;
if (v == (void *)1)
return f->start;
++p;
if ((void *)p >= (void *)f->stop)
return NULL;
return p;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
void *t = (void *)1;
loff_t l = 0;
for (; t && l < *pos; t = t_next(m, t, &l))
;
return t;
}
static void t_stop(struct seq_file *m, void *p)
{
}
static int t_show(struct seq_file *m, void *v)
{
const struct ftrace_pointer *fp = m->private;
struct ftrace_branch_data *p = v;
const char *f;
long percent;
if (v == (void *)1) {
if (fp->hit)
seq_printf(m, " miss hit %% ");
else
seq_printf(m, " correct incorrect %% ");
seq_printf(m, " Function "
seq_printf(m, " correct incorrect %% ");
seq_printf(m, " Function "
" File Line\n"
" ------- --------- - "
" -------- "
" ---- ----\n");
return 0;
}
return 0;
}
static inline long get_incorrect_percent(struct ftrace_branch_data *p)
{
long percent;
if (p->correct) {
percent = p->incorrect * 100;
percent /= p->correct + p->incorrect;
} else
percent = p->incorrect ? 100 : -1;
return percent;
}
static int branch_stat_show(struct seq_file *m, void *v)
{
struct ftrace_branch_data *p = v;
const char *f;
long percent;
/* Only print the file, not the path */
f = p->file + strlen(p->file);
@ -305,11 +258,7 @@ static int t_show(struct seq_file *m, void *v)
/*
* The miss is overlayed on correct, and hit on incorrect.
*/
if (p->correct) {
percent = p->incorrect * 100;
percent /= p->correct + p->incorrect;
} else
percent = p->incorrect ? 100 : -1;
percent = get_incorrect_percent(p);
seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect);
if (percent < 0)
@ -320,76 +269,143 @@ static int t_show(struct seq_file *m, void *v)
return 0;
}
static struct seq_operations tracing_likely_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int tracing_branch_open(struct inode *inode, struct file *file)
static void *annotated_branch_stat_start(void)
{
int ret;
ret = seq_open(file, &tracing_likely_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = (void *)inode->i_private;
}
return ret;
return __start_annotated_branch_profile;
}
static const struct file_operations tracing_branch_fops = {
.open = tracing_branch_open,
.read = seq_read,
.llseek = seq_lseek,
};
static void *
annotated_branch_stat_next(void *v, int idx)
{
struct ftrace_branch_data *p = v;
++p;
if ((void *)p >= (void *)__stop_annotated_branch_profile)
return NULL;
return p;
}
static int annotated_branch_stat_cmp(void *p1, void *p2)
{
struct ftrace_branch_data *a = p1;
struct ftrace_branch_data *b = p2;
long percent_a, percent_b;
percent_a = get_incorrect_percent(a);
percent_b = get_incorrect_percent(b);
if (percent_a < percent_b)
return -1;
if (percent_a > percent_b)
return 1;
else
return 0;
}
#ifdef CONFIG_PROFILE_ALL_BRANCHES
enum {
TRACE_BRANCH_OPT_ALL = 0x1
};
static struct tracer_opt branch_opts[] = {
{ TRACER_OPT(stat_all_branch, TRACE_BRANCH_OPT_ALL) },
{ }
};
static struct tracer_flags branch_flags = {
.val = 0,
.opts = branch_opts
};
extern unsigned long __start_branch_profile[];
extern unsigned long __stop_branch_profile[];
static const struct ftrace_pointer ftrace_branch_pos = {
.start = __start_branch_profile,
.stop = __stop_branch_profile,
.hit = 1,
};
#endif /* CONFIG_PROFILE_ALL_BRANCHES */
extern unsigned long __start_annotated_branch_profile[];
extern unsigned long __stop_annotated_branch_profile[];
static const struct ftrace_pointer ftrace_annotated_branch_pos = {
.start = __start_annotated_branch_profile,
.stop = __stop_annotated_branch_profile,
};
static __init int ftrace_branch_init(void)
static int all_branch_stat_headers(struct seq_file *m)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
entry = debugfs_create_file("profile_annotated_branch", 0444, d_tracer,
(void *)&ftrace_annotated_branch_pos,
&tracing_branch_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'profile_annotatet_branch' entry\n");
#ifdef CONFIG_PROFILE_ALL_BRANCHES
entry = debugfs_create_file("profile_branch", 0444, d_tracer,
(void *)&ftrace_branch_pos,
&tracing_branch_fops);
if (!entry)
pr_warning("Could not create debugfs"
" 'profile_branch' entry\n");
#endif
seq_printf(m, " miss hit %% ");
seq_printf(m, " Function "
" File Line\n"
" ------- --------- - "
" -------- "
" ---- ----\n");
return 0;
}
device_initcall(ftrace_branch_init);
static void *all_branch_stat_start(void)
{
return __start_branch_profile;
}
static void *
all_branch_stat_next(void *v, int idx)
{
struct ftrace_branch_data *p = v;
++p;
if ((void *)p >= (void *)__stop_branch_profile)
return NULL;
return p;
}
static int branch_set_flag(u32 old_flags, u32 bit, int set)
{
if (bit == TRACE_BRANCH_OPT_ALL) {
if (set) {
branch_trace.stat_headers = all_branch_stat_headers;
branch_trace.stat_start = all_branch_stat_start;
branch_trace.stat_next = all_branch_stat_next;
branch_trace.stat_cmp = NULL;
} else {
branch_trace.stat_headers =
annotated_branch_stat_headers;
branch_trace.stat_start = annotated_branch_stat_start;
branch_trace.stat_next = annotated_branch_stat_next;
branch_trace.stat_cmp = annotated_branch_stat_cmp;
}
init_tracer_stat(&branch_trace);
}
return 0;
}
#endif /* CONFIG_PROFILE_ALL_BRANCHES */
static struct tracer branch_trace __read_mostly =
{
.name = "branch",
#ifdef CONFIG_BRANCH_TRACER
.init = branch_trace_init,
.reset = branch_trace_reset,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_branch,
#endif /* CONFIG_FTRACE_SELFTEST */
#endif /* CONFIG_BRANCH_TRACER */
.stat_start = annotated_branch_stat_start,
.stat_next = annotated_branch_stat_next,
.stat_show = branch_stat_show,
.stat_headers = annotated_branch_stat_headers,
.stat_cmp = annotated_branch_stat_cmp,
#ifdef CONFIG_PROFILE_ALL_BRANCHES
.flags = &branch_flags,
.set_flag = branch_set_flag,
#endif
};
__init static int init_branch_trace(void)
{
#ifdef CONFIG_BRANCH_TRACER
int ret;
ret = register_ftrace_event(&trace_branch_event);
if (!ret) {
printk(KERN_WARNING "Warning: could not register branch events\n");
return 1;
}
#endif
return register_tracer(&branch_trace);
}
device_initcall(init_branch_trace);