dlan17/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

tracing: likely/unlikely branch annotation tracer

Browse Source 
Impact: new likely/unlikely branch tracer

This patch adds a way to record the instances of the likely() and unlikely()
branch condition annotations.

When "unlikely" is set in /debugfs/tracing/iter_ctrl the unlikely conditions
will be added to any of the ftrace tracers. The change takes effect when
a new tracer is passed into the current_tracer file.

For example:

 bash-3471  [003]   357.014755: [INCORRECT] sched_info_dequeued:sched_stats.h:177
 bash-3471  [003]   357.014756: [correct] update_curr:sched_fair.c:489
 bash-3471  [003]   357.014758: [correct] calc_delta_fair:sched_fair.c:411
 bash-3471  [003]   357.014759: [correct] account_group_exec_runtime:sched_stats.h:356
 bash-3471  [003]   357.014761: [correct] update_curr:sched_fair.c:489
 bash-3471  [003]   357.014763: [INCORRECT] calc_delta_fair:sched_fair.c:411
 bash-3471  [003]   357.014765: [correct] calc_delta_mine:sched.c:1279

Which shows the normal tracer heading, as well as whether the condition was
correct "[correct]" or was mistaken "[INCORRECT]", followed by the function,
file name and line number.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt
2008-11-12 11:52:02 +01:00
committed by Ingo Molnar
parent 1f0d69a9fc
commit 52f232cb72
5 changed files with 210 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/trace/trace.c
+29
View File
@@ -258,6 +258,9 @@ static const char *trace_options[] = {
"sched-tree",
"ftrace_printk",
"ftrace_preempt",
#ifdef CONFIG_UNLIKELY_TRACER
"unlikely",
#endif
NULL
};
@@ -1648,6 +1651,18 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
trace_seq_print_cont(s, iter);
break;
}
case TRACE_UNLIKELY: {
struct trace_unlikely *field;
trace_assign_type(field, entry);
trace_seq_printf(s, "[%s] %s:%s:%d\n",
field->correct ? "correct" : "INCORRECT",
field->func,
field->file,
field->line);
break;
}
default:
trace_seq_printf(s, "Unknown type %d\n", entry->type);
}
@@ -1787,6 +1802,18 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
return print_return_function(iter);
break;
}
case TRACE_UNLIKELY: {
struct trace_unlikely *field;
trace_assign_type(field, entry);
trace_seq_printf(s, "[%s] %s:%s:%d\n",
field->correct ? "correct" : "INCORRECT",
field->func,
field->file,
field->line);
break;
}
}
return TRACE_TYPE_HANDLED;
}
@@ -2592,6 +2619,7 @@ static int tracing_set_tracer(char *buf)
if (t == current_trace)
goto out;
trace_unlikely_disable();
if (current_trace && current_trace->reset)
current_trace->reset(tr);
@@ -2599,6 +2627,7 @@ static int tracing_set_tracer(char *buf)
if (t->init)
t->init(tr);
trace_unlikely_enable(tr);
out:
mutex_unlock(&trace_types_lock);