ftrace: extend sysprof plugin

add per CPU hrtimers.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 63 insertions, 4 deletions

diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index 6c139bc1be7e..ba55b871b3d9 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -5,19 +5,76 @@
  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
  *
  */
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <linux/debugfs.h>
 #include <linux/kallsyms.h>
+#include <linux/debugfs.h>
+#include <linux/hrtimer.h>
 #include <linux/uaccess.h>
-#include <linux/marker.h>
 #include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/fs.h>
 
 #include "trace.h"
 
 static struct trace_array       *ctx_trace;
 static int __read_mostly        tracer_enabled;
 
+static const unsigned long sample_period = 1000000;
+
+/*
+ * Per CPU hrtimers that do the profiling:
+ */
+static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer);
+
+static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer)
+{
+        /* trace here */
+        panic_timeout++;
+
+        hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
+
+        return HRTIMER_RESTART;
+}
+
+static void start_stack_timer(int cpu)
+{
+        struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
+
+        hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+        hrtimer->function = stack_trace_timer_fn;
+        hrtimer->cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
+
+        hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL);
+}
+
+static void start_stack_timers(void)
+{
+        cpumask_t saved_mask = current->cpus_allowed;
+        int cpu;
+
+        for_each_online_cpu(cpu) {
+                set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
+                start_stack_timer(cpu);
+                printk("started timer on cpu%d\n", cpu);
+        }
+        set_cpus_allowed_ptr(current, &saved_mask);
+}
+
+static void stop_stack_timer(int cpu)
+{
+        struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
+
+        hrtimer_cancel(hrtimer);
+        printk("cancelled timer on cpu%d\n", cpu);
+}
+
+static void stop_stack_timers(void)
+{
+        int cpu;
+
+        for_each_online_cpu(cpu)
+                stop_stack_timer(cpu);
+}
+
 static notrace void stack_reset(struct trace_array *tr)
 {
         int cpu;
@@ -31,11 +88,13 @@ static notrace void stack_reset(struct trace_array *tr)
 static notrace void start_stack_trace(struct trace_array *tr)
 {
         stack_reset(tr);
+        start_stack_timers();
         tracer_enabled = 1;
 }
 
 static notrace void stop_stack_trace(struct trace_array *tr)
 {
+        stop_stack_timers();
         tracer_enabled = 0;
 }