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authorIngo Molnar <mingo@elte.hu>2008-05-12 21:20:49 +0200
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 23:40:22 +0200
commitd618b3e6e50970a6248ac857653fdd49bcd3c045 (patch)
tree1bf01a4c4092b9db9b3690a980b5260170ec6567 /kernel/trace/trace_sysprof.c
parent9f6b4e3f4a24f2590f1c96f117fc45fbea9b0fa4 (diff)
downloadlinux-d618b3e6e50970a6248ac857653fdd49bcd3c045.tar.bz2
ftrace: sysprof updates
make the sample period configurable. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/trace/trace_sysprof.c')
-rw-r--r--kernel/trace/trace_sysprof.c70
1 files changed, 68 insertions, 2 deletions
diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index f9a09fe705b0..19406236b67b 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -20,11 +20,12 @@ static struct trace_array *sysprof_trace;
static int __read_mostly tracer_enabled;
/*
- * 10 msecs for now:
+ * 1 msec sample interval by default:
*/
-static const unsigned long sample_period = 1000000;
+static unsigned long sample_period = 1000000;
static const unsigned int sample_max_depth = 512;
+static DEFINE_MUTEX(sample_timer_lock);
/*
* Per CPU hrtimers that do the profiling:
*/
@@ -166,15 +167,19 @@ static notrace void stack_reset(struct trace_array *tr)
static notrace void start_stack_trace(struct trace_array *tr)
{
+ mutex_lock(&sample_timer_lock);
stack_reset(tr);
start_stack_timers();
tracer_enabled = 1;
+ mutex_unlock(&sample_timer_lock);
}
static notrace void stop_stack_trace(struct trace_array *tr)
{
+ mutex_lock(&sample_timer_lock);
stop_stack_timers();
tracer_enabled = 0;
+ mutex_unlock(&sample_timer_lock);
}
static notrace void stack_trace_init(struct trace_array *tr)
@@ -216,3 +221,64 @@ __init static int init_stack_trace(void)
return register_tracer(&stack_trace);
}
device_initcall(init_stack_trace);
+
+#define MAX_LONG_DIGITS 22
+
+static ssize_t
+sysprof_sample_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[MAX_LONG_DIGITS];
+ int r;
+
+ r = sprintf(buf, "%ld\n", nsecs_to_usecs(sample_period));
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+sysprof_sample_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[MAX_LONG_DIGITS];
+ unsigned long val;
+
+ if (cnt > MAX_LONG_DIGITS-1)
+ cnt = MAX_LONG_DIGITS-1;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ val = simple_strtoul(buf, NULL, 10);
+ /*
+ * Enforce a minimum sample period of 100 usecs:
+ */
+ if (val < 100)
+ val = 100;
+
+ mutex_lock(&sample_timer_lock);
+ stop_stack_timers();
+ sample_period = val * 1000;
+ start_stack_timers();
+ mutex_unlock(&sample_timer_lock);
+
+ return cnt;
+}
+
+static struct file_operations sysprof_sample_fops = {
+ .read = sysprof_sample_read,
+ .write = sysprof_sample_write,
+};
+
+void init_tracer_sysprof_debugfs(struct dentry *d_tracer)
+{
+ struct dentry *entry;
+
+ entry = debugfs_create_file("sysprof_sample_period", 0644,
+ d_tracer, NULL, &sysprof_sample_fops);
+ if (entry)
+ return;
+ pr_warning("Could not create debugfs 'dyn_ftrace_total_info' entry\n");
+}