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Subject[PATCH 08/18] tracing: print out start and stop in latency traces
From: Steven Rostedt <srostedt@redhat.com>

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>
---
kernel/trace/trace.c | 19 +++++++++++--------
kernel/trace/trace.h | 3 ---
2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0f08816..df2c9f7 100644
--- 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
--- 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;
--
1.6.3.3
--


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