ftrace: fix time offset
fix time offset calculations and ordering, plus make code more consistent.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c736dd2..8755a43 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -120,7 +120,7 @@
* structure. (this way the maximum trace is permanently saved,
* for later retrieval via /debugfs/tracing/latency_trace)
*/
-static void notrace
+static notrace void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct trace_array_cpu *data = tr->data[cpu];
@@ -333,15 +333,16 @@
mutex_unlock(&trace_types_lock);
}
-void notrace tracing_reset(struct trace_array_cpu *data)
+notrace void tracing_reset(struct trace_array_cpu *data)
{
data->trace_idx = 0;
data->trace_current = head_page(data);
data->trace_current_idx = 0;
+ data->time_offset = 0;
}
#ifdef CONFIG_FTRACE
-static void notrace
+static notrace void
function_trace_call(unsigned long ip, unsigned long parent_ip)
{
struct trace_array *tr = &global_trace;
@@ -398,7 +399,7 @@
notrace void trace_stop_cmdline_recording(void);
-static void notrace trace_save_cmdline(struct task_struct *tsk)
+static notrace void trace_save_cmdline(struct task_struct *tsk)
{
unsigned map;
unsigned idx;
@@ -624,6 +625,7 @@
iter->idx++;
iter->next_idx[next_cpu]++;
iter->next_page_idx[next_cpu]++;
+
if (iter->next_page_idx[next_cpu] >= ENTRIES_PER_PAGE) {
struct trace_array_cpu *data = iter->tr->data[next_cpu];
@@ -635,19 +637,21 @@
data->trace_pages.next;
}
}
+ iter->prev_ent = iter->ent;
+ iter->prev_cpu = iter->cpu;
+
iter->ent = next;
iter->cpu = next_cpu;
return next ? iter : NULL;
}
-static void notrace *
-s_next(struct seq_file *m, void *v, loff_t *pos)
+static notrace void *s_next(struct seq_file *m, void *v, loff_t *pos)
{
struct trace_iterator *iter = m->private;
- void *ent;
void *last_ent = iter->ent;
int i = (int)*pos;
+ void *ent;
(*pos)++;
@@ -693,6 +697,8 @@
iter->ent = NULL;
iter->cpu = 0;
iter->idx = -1;
+ iter->prev_ent = NULL;
+ iter->prev_cpu = -1;
for_each_possible_cpu(i) {
iter->next_idx[i] = 0;
@@ -752,7 +758,7 @@
# define IP_FMT "%016lx"
#endif
-static void notrace
+static notrace void
seq_print_ip_sym(struct seq_file *m, unsigned long ip, unsigned long sym_flags)
{
if (!ip) {
@@ -769,7 +775,7 @@
seq_printf(m, " <" IP_FMT ">", ip);
}
-static void notrace print_lat_help_header(struct seq_file *m)
+static notrace void print_lat_help_header(struct seq_file *m)
{
seq_puts(m, "# _------=> CPU# \n");
seq_puts(m, "# / _-----=> irqs-off \n");
@@ -782,14 +788,14 @@
seq_puts(m, "# \\ / ||||| \\ | / \n");
}
-static void notrace print_func_help_header(struct seq_file *m)
+static notrace void print_func_help_header(struct seq_file *m)
{
seq_puts(m, "# TASK-PID CPU# TIMESTAMP FUNCTION\n");
seq_puts(m, "# | | | | |\n");
}
-static void notrace
+static notrace void
print_trace_header(struct seq_file *m, struct trace_iterator *iter)
{
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
@@ -858,7 +864,7 @@
seq_puts(m, "\n");
}
-static void notrace
+static notrace void
lat_print_generic(struct seq_file *m, struct trace_entry *entry, int cpu)
{
int hardirq, softirq;
@@ -895,7 +901,7 @@
unsigned long preempt_mark_thresh = 100;
-static void notrace
+static notrace void
lat_print_timestamp(struct seq_file *m, unsigned long long abs_usecs,
unsigned long rel_usecs)
{
@@ -910,7 +916,7 @@
static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
-static void notrace
+static notrace void
print_lat_fmt(struct seq_file *m, struct trace_iterator *iter,
unsigned int trace_idx, int cpu)
{
@@ -966,20 +972,50 @@
}
}
-static void notrace
+static notrace void sync_time_offset(struct trace_iterator *iter)
+{
+ struct trace_array_cpu *prev_array, *array;
+ struct trace_entry *prev_entry, *entry;
+ cycle_t prev_t, t;
+
+ entry = iter->ent;
+ prev_entry = iter->prev_ent;
+ if (!prev_entry)
+ return;
+
+ prev_array = iter->tr->data[iter->prev_cpu];
+ array = iter->tr->data[iter->cpu];
+
+ prev_t = prev_entry->t + prev_array->time_offset;
+ t = entry->t + array->time_offset;
+
+ /*
+ * If time goes backwards we increase the offset of
+ * the current array, to not have observable time warps.
+ * This will quickly synchronize the time offsets of
+ * multiple CPUs:
+ */
+ if (t < prev_t)
+ array->time_offset += prev_t - t;
+}
+
+static notrace void
print_trace_fmt(struct seq_file *m, struct trace_iterator *iter)
{
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
- struct trace_entry *entry = iter->ent;
+ struct trace_entry *entry;
unsigned long usec_rem;
unsigned long long t;
unsigned long secs;
char *comm;
int S;
+ sync_time_offset(iter);
+ entry = iter->ent;
+
comm = trace_find_cmdline(iter->ent->pid);
- t = ns2usecs(entry->t);
+ t = ns2usecs(entry->t + iter->tr->data[iter->cpu]->time_offset);
usec_rem = do_div(t, 1000000ULL);
secs = (unsigned long)t;
@@ -1158,7 +1194,7 @@
}
-static void notrace *
+static notrace void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct tracer *t = m->private;
@@ -1374,8 +1410,7 @@
int r;
r = sprintf(buf, "%ld\n", tr->ctrl);
- return simple_read_from_buffer(ubuf, cnt, ppos,
- buf, r);
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t