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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
Ingo Molnar
parent
dbd0b4b330
commit
e302cf3f96
@ -18,10 +18,13 @@
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#include "trace.h"
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#include "trace_output.h"
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static struct tracer branch_trace;
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#ifdef CONFIG_BRANCH_TRACER
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static int branch_tracing_enabled __read_mostly;
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static DEFINE_MUTEX(branch_tracing_mutex);
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static struct trace_array *branch_tracer;
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static void
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@ -178,6 +181,7 @@ trace_branch_print(struct trace_seq *s, struct trace_entry *entry, int flags)
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return 0;
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}
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static struct trace_event trace_branch_event = {
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.type = TRACE_BRANCH,
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.trace = trace_branch_print,
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@ -187,30 +191,6 @@ static struct trace_event trace_branch_event = {
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.binary = trace_nop_print,
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};
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struct tracer branch_trace __read_mostly =
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{
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.name = "branch",
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.init = branch_trace_init,
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.reset = branch_trace_reset,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_branch,
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#endif
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};
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__init static int init_branch_trace(void)
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{
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int ret;
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ret = register_ftrace_event(&trace_branch_event);
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if (!ret) {
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printk(KERN_WARNING "Warning: could not register branch events\n");
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return 1;
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}
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return register_tracer(&branch_trace);
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}
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device_initcall(init_branch_trace);
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#else
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static inline
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void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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@ -236,65 +216,38 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
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}
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EXPORT_SYMBOL(ftrace_likely_update);
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struct ftrace_pointer {
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void *start;
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void *stop;
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int hit;
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};
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extern unsigned long __start_annotated_branch_profile[];
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extern unsigned long __stop_annotated_branch_profile[];
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static void *
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t_next(struct seq_file *m, void *v, loff_t *pos)
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static int annotated_branch_stat_headers(struct seq_file *m)
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{
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const struct ftrace_pointer *f = m->private;
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struct ftrace_branch_data *p = v;
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(*pos)++;
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if (v == (void *)1)
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return f->start;
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++p;
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if ((void *)p >= (void *)f->stop)
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return NULL;
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return p;
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}
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static void *t_start(struct seq_file *m, loff_t *pos)
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{
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void *t = (void *)1;
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loff_t l = 0;
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for (; t && l < *pos; t = t_next(m, t, &l))
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;
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return t;
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}
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static void t_stop(struct seq_file *m, void *p)
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{
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}
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static int t_show(struct seq_file *m, void *v)
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{
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const struct ftrace_pointer *fp = m->private;
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struct ftrace_branch_data *p = v;
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const char *f;
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long percent;
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if (v == (void *)1) {
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if (fp->hit)
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seq_printf(m, " miss hit %% ");
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else
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seq_printf(m, " correct incorrect %% ");
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seq_printf(m, " Function "
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seq_printf(m, " correct incorrect %% ");
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seq_printf(m, " Function "
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" File Line\n"
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" ------- --------- - "
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" -------- "
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" ---- ----\n");
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return 0;
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}
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return 0;
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}
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static inline long get_incorrect_percent(struct ftrace_branch_data *p)
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{
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long percent;
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if (p->correct) {
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percent = p->incorrect * 100;
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percent /= p->correct + p->incorrect;
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} else
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percent = p->incorrect ? 100 : -1;
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return percent;
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}
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static int branch_stat_show(struct seq_file *m, void *v)
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{
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struct ftrace_branch_data *p = v;
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const char *f;
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long percent;
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/* Only print the file, not the path */
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f = p->file + strlen(p->file);
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@ -305,11 +258,7 @@ static int t_show(struct seq_file *m, void *v)
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/*
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* The miss is overlayed on correct, and hit on incorrect.
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*/
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if (p->correct) {
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percent = p->incorrect * 100;
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percent /= p->correct + p->incorrect;
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} else
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percent = p->incorrect ? 100 : -1;
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percent = get_incorrect_percent(p);
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seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect);
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if (percent < 0)
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@ -320,76 +269,143 @@ static int t_show(struct seq_file *m, void *v)
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return 0;
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}
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static struct seq_operations tracing_likely_seq_ops = {
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.start = t_start,
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.next = t_next,
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.stop = t_stop,
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.show = t_show,
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};
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static int tracing_branch_open(struct inode *inode, struct file *file)
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static void *annotated_branch_stat_start(void)
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{
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int ret;
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ret = seq_open(file, &tracing_likely_seq_ops);
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if (!ret) {
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struct seq_file *m = file->private_data;
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m->private = (void *)inode->i_private;
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}
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return ret;
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return __start_annotated_branch_profile;
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}
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static const struct file_operations tracing_branch_fops = {
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.open = tracing_branch_open,
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.read = seq_read,
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.llseek = seq_lseek,
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};
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static void *
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annotated_branch_stat_next(void *v, int idx)
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{
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struct ftrace_branch_data *p = v;
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++p;
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if ((void *)p >= (void *)__stop_annotated_branch_profile)
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return NULL;
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return p;
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}
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static int annotated_branch_stat_cmp(void *p1, void *p2)
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{
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struct ftrace_branch_data *a = p1;
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struct ftrace_branch_data *b = p2;
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long percent_a, percent_b;
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percent_a = get_incorrect_percent(a);
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percent_b = get_incorrect_percent(b);
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if (percent_a < percent_b)
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return -1;
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if (percent_a > percent_b)
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return 1;
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else
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return 0;
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}
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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enum {
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TRACE_BRANCH_OPT_ALL = 0x1
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};
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static struct tracer_opt branch_opts[] = {
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{ TRACER_OPT(stat_all_branch, TRACE_BRANCH_OPT_ALL) },
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{ }
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};
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static struct tracer_flags branch_flags = {
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.val = 0,
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.opts = branch_opts
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};
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extern unsigned long __start_branch_profile[];
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extern unsigned long __stop_branch_profile[];
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static const struct ftrace_pointer ftrace_branch_pos = {
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.start = __start_branch_profile,
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.stop = __stop_branch_profile,
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.hit = 1,
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};
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#endif /* CONFIG_PROFILE_ALL_BRANCHES */
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extern unsigned long __start_annotated_branch_profile[];
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extern unsigned long __stop_annotated_branch_profile[];
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static const struct ftrace_pointer ftrace_annotated_branch_pos = {
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.start = __start_annotated_branch_profile,
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.stop = __stop_annotated_branch_profile,
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};
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static __init int ftrace_branch_init(void)
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static int all_branch_stat_headers(struct seq_file *m)
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{
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struct dentry *d_tracer;
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struct dentry *entry;
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d_tracer = tracing_init_dentry();
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entry = debugfs_create_file("profile_annotated_branch", 0444, d_tracer,
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(void *)&ftrace_annotated_branch_pos,
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&tracing_branch_fops);
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if (!entry)
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pr_warning("Could not create debugfs "
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"'profile_annotatet_branch' entry\n");
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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entry = debugfs_create_file("profile_branch", 0444, d_tracer,
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(void *)&ftrace_branch_pos,
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&tracing_branch_fops);
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if (!entry)
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pr_warning("Could not create debugfs"
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" 'profile_branch' entry\n");
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#endif
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seq_printf(m, " miss hit %% ");
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seq_printf(m, " Function "
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" File Line\n"
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" ------- --------- - "
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" -------- "
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" ---- ----\n");
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return 0;
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}
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device_initcall(ftrace_branch_init);
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static void *all_branch_stat_start(void)
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{
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return __start_branch_profile;
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}
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static void *
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all_branch_stat_next(void *v, int idx)
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{
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struct ftrace_branch_data *p = v;
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++p;
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if ((void *)p >= (void *)__stop_branch_profile)
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return NULL;
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return p;
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}
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static int branch_set_flag(u32 old_flags, u32 bit, int set)
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{
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if (bit == TRACE_BRANCH_OPT_ALL) {
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if (set) {
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branch_trace.stat_headers = all_branch_stat_headers;
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branch_trace.stat_start = all_branch_stat_start;
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branch_trace.stat_next = all_branch_stat_next;
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branch_trace.stat_cmp = NULL;
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} else {
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branch_trace.stat_headers =
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annotated_branch_stat_headers;
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branch_trace.stat_start = annotated_branch_stat_start;
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branch_trace.stat_next = annotated_branch_stat_next;
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branch_trace.stat_cmp = annotated_branch_stat_cmp;
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}
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init_tracer_stat(&branch_trace);
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}
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return 0;
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}
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#endif /* CONFIG_PROFILE_ALL_BRANCHES */
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static struct tracer branch_trace __read_mostly =
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{
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.name = "branch",
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#ifdef CONFIG_BRANCH_TRACER
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.init = branch_trace_init,
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.reset = branch_trace_reset,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_branch,
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#endif /* CONFIG_FTRACE_SELFTEST */
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#endif /* CONFIG_BRANCH_TRACER */
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.stat_start = annotated_branch_stat_start,
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.stat_next = annotated_branch_stat_next,
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.stat_show = branch_stat_show,
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.stat_headers = annotated_branch_stat_headers,
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.stat_cmp = annotated_branch_stat_cmp,
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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.flags = &branch_flags,
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.set_flag = branch_set_flag,
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#endif
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};
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__init static int init_branch_trace(void)
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{
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#ifdef CONFIG_BRANCH_TRACER
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int ret;
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ret = register_ftrace_event(&trace_branch_event);
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if (!ret) {
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printk(KERN_WARNING "Warning: could not register branch events\n");
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return 1;
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}
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#endif
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return register_tracer(&branch_trace);
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}
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device_initcall(init_branch_trace);
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