tracing: print out start and stop in latency traces

During development of the tracer, we would copy information from
the live tracer to the max tracer with one memcpy. Since then we
added a generic ring buffer and we handle the copies differently now.
Unfortunately, we never copied the critical section information, and
we lost the output:

 #  => started at: kmem_cache_alloc
 #  => ended at:   kmem_cache_alloc

This patch adds back the critical start and end copying as well as
removes the unused "trace_idx" and "overrun" fields of the
trace_array_cpu structure.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0f08816..df2c9f7 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -407,19 +407,22 @@ static void
 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
        struct trace_array_cpu *data = tr->data[cpu];
+       struct trace_array_cpu *max_data = tr->data[cpu];
 
        max_tr.cpu = cpu;
        max_tr.time_start = data->preempt_timestamp;
 
-       data = max_tr.data[cpu];
-       data->saved_latency = tracing_max_latency;
+       max_data = max_tr.data[cpu];
+       max_data->saved_latency = tracing_max_latency;
+       max_data->critical_start = data->critical_start;
+       max_data->critical_end = data->critical_end;
 
        memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
-       data->pid = tsk->pid;
-       data->uid = task_uid(tsk);
-       data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
-       data->policy = tsk->policy;
-       data->rt_priority = tsk->rt_priority;
+       max_data->pid = tsk->pid;
+       max_data->uid = task_uid(tsk);
+       max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
+       max_data->policy = tsk->policy;
+       max_data->rt_priority = tsk->rt_priority;
 
        /* record this tasks comm */
        tracing_record_cmdline(tsk);
@@ -1501,7 +1504,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
                seq_puts(m, "\n#  => ended at:   ");
                seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
                trace_print_seq(m, &iter->seq);
-               seq_puts(m, "#\n");
+               seq_puts(m, "\n#\n");
        }
 
        seq_puts(m, "#\n");

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e2c06b2..f2af713 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -234,9 +234,6 @@ struct trace_array_cpu {
        atomic_t                disabled;
        void                    *buffer_page;   /* ring buffer spare */
 
-       /* these fields get copied into max-trace: */
-       unsigned long           trace_idx;
-       unsigned long           overrun;
        unsigned long           saved_latency;
        unsigned long           critical_start;
        unsigned long           critical_end;