From 5b058bcde961bf28678a70e44c079107313543b6 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Tue, 17 Feb 2009 18:35:34 +0100 Subject: tracing/function-graph-tracer: trace the idle tasks When the function graph tracer is activated, it iterates over the task_list to allocate a stack to store the return addresses. But the per cpu idle tasks are not iterated by using do_each_thread / while_each_thread. So we have to iterate on them manually. This fixes somes weirdness in the traces and many losses of traces. Examples on two cpus: 0) Xorg-4287 | 2.906 us | } 0) Xorg-4287 | 3.965 us | } 0) Xorg-4287 | 5.302 us | } ------------------------------------------ 0) Xorg-4287 => -0 ------------------------------------------ 0) -0 | 2.861 us | } 0) -0 | 0.526 us | set_normalized_timespec(); 0) -0 | 7.201 us | } 0) -0 | 8.214 us | } 0) -0 | | clockevents_program_event() { 0) -0 | | lapic_next_event() { 0) -0 | 0.510 us | native_apic_mem_write(); 0) -0 | 1.546 us | } 0) -0 | 2.583 us | } 0) -0 | + 12.435 us | } 0) -0 | + 13.470 us | } 0) -0 | 0.608 us | _spin_unlock_irqrestore(); 0) -0 | + 23.270 us | } 0) -0 | + 24.336 us | } 0) -0 | + 25.417 us | } 0) -0 | 0.593 us | _spin_unlock(); 0) -0 | + 41.869 us | } 0) -0 | + 42.906 us | } 0) -0 | + 95.035 us | } 0) -0 | 0.540 us | menu_reflect(); 0) -0 | ! 100.404 us | } 0) -0 | 0.564 us | mce_idle_callback(); 0) -0 | | enter_idle() { 0) -0 | 0.526 us | mce_idle_callback(); 0) -0 | 1.757 us | } 0) -0 | | cpuidle_idle_call() { 0) -0 | | menu_select() { 0) -0 | 0.525 us | pm_qos_requirement(); 0) -0 | 0.518 us | tick_nohz_get_sleep_length(); 0) -0 | 2.621 us | } [...] 1) -0 | 0.518 us | touch_softlockup_watchdog(); 1) -0 | + 14.355 us | } 1) -0 | + 22.840 us | } 1) -0 | + 25.949 us | } 1) -0 | | handle_irq() { 1) -0 | 0.511 us | irq_to_desc(); 1) -0 | | handle_edge_irq() { 1) -0 | 0.638 us | _spin_lock(); 1) -0 | | ack_apic_edge() { 1) -0 | 0.510 us | irq_to_desc(); 1) -0 | | move_native_irq() { 1) -0 | 0.510 us | irq_to_desc(); 1) -0 | 1.532 us | } 1) -0 | 0.511 us | native_apic_mem_write(); ------------------------------------------ 1) -0 => cat-5073 ------------------------------------------ 1) cat-5073 | 3.731 us | } 1) cat-5073 | | run_local_timers() { 1) cat-5073 | 0.533 us | hrtimer_run_queues(); 1) cat-5073 | | raise_softirq() { 1) cat-5073 | | __raise_softirq_irqoff() { 1) cat-5073 | | /* nr: 1 */ 1) cat-5073 | 2.718 us | } 1) cat-5073 | 3.814 us | } Signed-off-by: Frederic Weisbecker Cc: Steven Rostedt Cc: Arnaldo Carvalho de Melo Signed-off-by: Ingo Molnar --- kernel/trace/ftrace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'kernel/trace/ftrace.c') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9a236ffe2aa4..fdf913dfc7e8 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2033,7 +2033,7 @@ free: static int start_graph_tracing(void) { struct ftrace_ret_stack **ret_stack_list; - int ret; + int ret, cpu; ret_stack_list = kmalloc(FTRACE_RETSTACK_ALLOC_SIZE * sizeof(struct ftrace_ret_stack *), @@ -2042,6 +2042,10 @@ static int start_graph_tracing(void) if (!ret_stack_list) return -ENOMEM; + /* The cpu_boot init_task->ret_stack will never be freed */ + for_each_online_cpu(cpu) + ftrace_graph_init_task(idle_task(cpu)); + do { ret = alloc_retstack_tasklist(ret_stack_list); } while (ret == -EAGAIN); -- cgit v1.2.3-59-g8ed1b