tracing: only show tracing_max_latency when latency tracer configured
The tracing_max_latency file should only be present when one of the
latency tracers ({preempt|irqs}off, wakeup*) are enabled.
This patch also removes tracing_thresh when latency tracers are not
enabled, as well as compiles out code that is only used for latency
tracers.
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 63dbc7f..0f08816 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -43,9 +43,6 @@
#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE)
-unsigned long __read_mostly tracing_max_latency;
-unsigned long __read_mostly tracing_thresh;
-
/*
* On boot up, the ring buffer is set to the minimum size, so that
* we do not waste memory on systems that are not using tracing.
@@ -338,45 +335,6 @@
int trace_clock_id;
-/*
- * ftrace_max_lock is used to protect the swapping of buffers
- * when taking a max snapshot. The buffers themselves are
- * protected by per_cpu spinlocks. But the action of the swap
- * needs its own lock.
- *
- * This is defined as a raw_spinlock_t in order to help
- * with performance when lockdep debugging is enabled.
- */
-static raw_spinlock_t ftrace_max_lock =
- (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
-
-/*
- * Copy the new maximum trace into the separate maximum-trace
- * structure. (this way the maximum trace is permanently saved,
- * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
- */
-static void
-__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
-{
- struct trace_array_cpu *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;
-
- 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;
-
- /* record this tasks comm */
- tracing_record_cmdline(tsk);
-}
-
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
int len;
@@ -420,6 +378,53 @@
return cnt;
}
+/*
+ * ftrace_max_lock is used to protect the swapping of buffers
+ * when taking a max snapshot. The buffers themselves are
+ * protected by per_cpu spinlocks. But the action of the swap
+ * needs its own lock.
+ *
+ * This is defined as a raw_spinlock_t in order to help
+ * with performance when lockdep debugging is enabled.
+ *
+ * It is also used in other places outside the update_max_tr
+ * so it needs to be defined outside of the
+ * CONFIG_TRACER_MAX_TRACE.
+ */
+static raw_spinlock_t ftrace_max_lock =
+ (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+unsigned long __read_mostly tracing_max_latency;
+unsigned long __read_mostly tracing_thresh;
+
+/*
+ * Copy the new maximum trace into the separate maximum-trace
+ * structure. (this way the maximum trace is permanently saved,
+ * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
+ */
+static void
+__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
+{
+ struct trace_array_cpu *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;
+
+ 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;
+
+ /* record this tasks comm */
+ tracing_record_cmdline(tsk);
+}
+
/**
* update_max_tr - snapshot all trace buffers from global_trace to max_tr
* @tr: tracer
@@ -476,6 +481,7 @@
__update_max_tr(tr, tsk, cpu);
__raw_spin_unlock(&ftrace_max_lock);
}
+#endif /* CONFIG_TRACER_MAX_TRACE */
/**
* register_tracer - register a tracer with the ftrace system.
@@ -3952,11 +3958,13 @@
trace_create_file("current_tracer", 0644, d_tracer,
&global_trace, &set_tracer_fops);
+#ifdef CONFIG_TRACER_MAX_TRACE
trace_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency, &tracing_max_lat_fops);
trace_create_file("tracing_thresh", 0644, d_tracer,
&tracing_thresh, &tracing_max_lat_fops);
+#endif
trace_create_file("README", 0444, d_tracer,
NULL, &tracing_readme_fops);