[PATCH 2/2] tracing/branch-tracer: adapt to the stat tracing API
From: Frederic Weisbecker
Date: Sat Dec 27 2008 - 17:47:26 EST
This patch adapts the branch tracer to the tracing API.
This is not really for inclusion but more likely 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@xxxxxxxxx>
---
kernel/trace/trace_branch.c | 268 +++++++++++++++++++++++--------------------
1 files changed, 142 insertions(+), 126 deletions(-)
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index c15222a..4785a3b 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -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)
@@ -236,66 +216,39 @@ 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;
+ seq_printf(m, " correct incorrect %% ");
+ seq_printf(m, " Function "
+ " File Line\n"
+ " ------- --------- - "
+ " -------- "
+ " ---- ----\n");
+ return 0;
}
-static void *t_start(struct seq_file *m, loff_t *pos)
+static inline long get_incorrect_percent(struct ftrace_branch_data *p)
{
- void *t = (void *)1;
- loff_t l = 0;
-
- for (; t && l < *pos; t = t_next(m, t, &l))
- ;
+ long percent;
- return t;
-}
+ if (p->correct) {
+ percent = p->incorrect * 100;
+ percent /= p->correct + p->incorrect;
+ } else
+ percent = p->incorrect ? 100 : -1;
-static void t_stop(struct seq_file *m, void *p)
-{
+ return percent;
}
-static int t_show(struct seq_file *m, void *v)
+static int branch_stat_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 "
- " File Line\n"
- " ------- --------- - "
- " -------- "
- " ---- ----\n");
- return 0;
- }
-
/* Only print the file, not the path */
f = p->file + strlen(p->file);
while (f >= p->file && *f != '/')
@@ -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 void *annotated_branch_stat_start(void)
+{
+ return __start_annotated_branch_profile;
+}
-static int tracing_branch_open(struct inode *inode, struct file *file)
+static void *
+annotated_branch_stat_next(void *v, int idx)
{
- int ret;
+ struct ftrace_branch_data *p = v;
- ret = seq_open(file, &tracing_likely_seq_ops);
- if (!ret) {
- struct seq_file *m = file->private_data;
- m->private = (void *)inode->i_private;
- }
+ ++p;
- return ret;
+ if ((void *)p >= (void *)__stop_annotated_branch_profile)
+ return NULL;
+
+ return p;
}
-static const struct file_operations tracing_branch_fops = {
- .open = tracing_branch_open,
- .read = seq_read,
- .llseek = seq_lseek,
-};
+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
-extern unsigned long __start_branch_profile[];
-extern unsigned long __stop_branch_profile[];
+enum {
+ TRACE_BRANCH_OPT_ALL = 0x1
+};
-static const struct ftrace_pointer ftrace_branch_pos = {
- .start = __start_branch_profile,
- .stop = __stop_branch_profile,
- .hit = 1,
+static struct tracer_opt branch_opts[] = {
+ { TRACER_OPT(stat_all_branch, TRACE_BRANCH_OPT_ALL) },
+ { }
};
-#endif /* CONFIG_PROFILE_ALL_BRANCHES */
+static struct tracer_flags branch_flags = {
+ .val = 0,
+ .opts = branch_opts
+};
-extern unsigned long __start_annotated_branch_profile[];
-extern unsigned long __stop_annotated_branch_profile[];
+extern unsigned long __start_branch_profile[];
+extern unsigned long __stop_branch_profile[];
-static const struct ftrace_pointer ftrace_annotated_branch_pos = {
- .start = __start_annotated_branch_profile,
- .stop = __stop_annotated_branch_profile,
-};
+static int all_branch_stat_headers(struct seq_file *m)
+{
+ seq_printf(m, " miss hit %% ");
+ seq_printf(m, " Function "
+ " File Line\n"
+ " ------- --------- - "
+ " -------- "
+ " ---- ----\n");
+ return 0;
+}
-static __init int ftrace_branch_init(void)
+static void *all_branch_stat_start(void)
{
- struct dentry *d_tracer;
- struct dentry *entry;
+ return __start_branch_profile;
+}
+
+static void *
+all_branch_stat_next(void *v, int idx)
+{
+ struct ftrace_branch_data *p = v;
- d_tracer = tracing_init_dentry();
+ ++p;
- 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");
+ if ((void *)p >= (void *)__stop_branch_profile)
+ return NULL;
-#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
+ 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;
}
-device_initcall(ftrace_branch_init);
+#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);
--
1.6.0.4
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