tracing: add lock depth to entries
This patch adds the lock depth of the big kernel lock to the generic
entry header. This way we can see the depth of the lock and help
in removing the BKL.
Example:
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| /_--=> lock-depth
# |||||/ delay
# cmd pid |||||| time | caller
# \ / |||||| \ | /
<idle>-0 2.N..3 5902255250us+: lock_acquire: read rcu_read_lock
<idle>-0 2.N..3 5902255253us+: lock_release: rcu_read_lock
<idle>-0 2dN..3 5902255257us+: lock_acquire: xtime_lock
<idle>-0 2dN..4 5902255259us : lock_acquire: clocksource_lock
<idle>-0 2dN..4 5902255261us+: lock_release: clocksource_lock
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index ee791a9..48af493 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -368,6 +368,7 @@
print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
{
int hardirq, softirq;
+ int ret;
hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
@@ -382,6 +383,13 @@
hardirq ? 'h' : softirq ? 's' : '.'))
return 0;
+ if (entry->lock_depth < 0)
+ ret = trace_seq_putc(s, '.');
+ else
+ ret = trace_seq_printf(s, "%d", entry->lock_depth);
+ if (!ret)
+ return 0;
+
if (entry->preempt_count)
return trace_seq_printf(s, "%x", entry->preempt_count);
return trace_seq_puts(s, ".");
@@ -1001,8 +1009,8 @@
seq_printf(s, "#%.*s / _----=> need-resched \n", size, spaces);
seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
seq_printf(s, "#%.*s|| / _--=> preempt-depth \n", size, spaces);
- seq_printf(s, "#%.*s||| / \n", size, spaces);
- seq_printf(s, "#%.*s|||| \n", size, spaces);
+ seq_printf(s, "#%.*s||| / _-=> lock-depth \n", size, spaces);
+ seq_printf(s, "#%.*s|||| / \n", size, spaces);
}
static void print_graph_headers(struct seq_file *s)
@@ -1021,7 +1029,7 @@
if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
seq_printf(s, " TASK/PID ");
if (lat)
- seq_printf(s, "||||");
+ seq_printf(s, "|||||");
if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
seq_printf(s, " DURATION ");
seq_printf(s, " FUNCTION CALLS\n");
@@ -1035,7 +1043,7 @@
if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
seq_printf(s, " | | ");
if (lat)
- seq_printf(s, "||||");
+ seq_printf(s, "|||||");
if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
seq_printf(s, " | | ");
seq_printf(s, " | | | |\n");