2 * trace irqs off critical timings
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 * From code in the latency_tracer, that is:
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 William Lee Irwin III
12 #include <linux/kallsyms.h>
13 #include <linux/debugfs.h>
14 #include <linux/uaccess.h>
15 #include <linux/module.h>
16 #include <linux/ftrace.h>
21 static struct trace_array *irqsoff_trace __read_mostly;
22 static int tracer_enabled __read_mostly;
24 static DEFINE_PER_CPU(int, tracing_cpu);
26 static DEFINE_SPINLOCK(max_trace_lock);
29 TRACER_IRQS_OFF = (1 << 1),
30 TRACER_PREEMPT_OFF = (1 << 2),
33 static int trace_type __read_mostly;
35 static int save_lat_flag;
37 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
38 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
40 #ifdef CONFIG_PREEMPT_TRACER
44 return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
47 # define preempt_trace() (0)
50 #ifdef CONFIG_IRQSOFF_TRACER
54 return ((trace_type & TRACER_IRQS_OFF) &&
58 # define irq_trace() (0)
61 #define TRACE_DISPLAY_GRAPH 1
63 static struct tracer_opt trace_opts[] = {
64 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
65 /* display latency trace as call graph */
66 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
71 static struct tracer_flags tracer_flags = {
76 #define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
79 * Sequence count - we record it when starting a measurement and
80 * skip the latency if the sequence has changed - some other section
81 * did a maximum and could disturb our measurement with serial console
82 * printouts, etc. Truly coinciding maximum latencies should be rare
83 * and what happens together happens separately as well, so this doesnt
84 * decrease the validity of the maximum found:
86 static __cacheline_aligned_in_smp unsigned long max_sequence;
88 #ifdef CONFIG_FUNCTION_TRACER
90 * Prologue for the preempt and irqs off function tracers.
92 * Returns 1 if it is OK to continue, and data->disabled is
94 * 0 if the trace is to be ignored, and data->disabled
97 * Note, this function is also used outside this ifdef but
98 * inside the #ifdef of the function graph tracer below.
99 * This is OK, since the function graph tracer is
100 * dependent on the function tracer.
102 static int func_prolog_dec(struct trace_array *tr,
103 struct trace_array_cpu **data,
104 unsigned long *flags)
110 * Does not matter if we preempt. We test the flags
111 * afterward, to see if irqs are disabled or not.
112 * If we preempt and get a false positive, the flags
115 cpu = raw_smp_processor_id();
116 if (likely(!per_cpu(tracing_cpu, cpu)))
119 local_save_flags(*flags);
120 /* slight chance to get a false positive on tracing_cpu */
121 if (!irqs_disabled_flags(*flags))
124 *data = tr->data[cpu];
125 disabled = atomic_inc_return(&(*data)->disabled);
127 if (likely(disabled == 1))
130 atomic_dec(&(*data)->disabled);
136 * irqsoff uses its own tracer function to keep the overhead down:
139 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
141 struct trace_array *tr = irqsoff_trace;
142 struct trace_array_cpu *data;
145 if (!func_prolog_dec(tr, &data, &flags))
148 trace_function(tr, ip, parent_ip, flags, preempt_count());
150 atomic_dec(&data->disabled);
153 static struct ftrace_ops trace_ops __read_mostly =
155 .func = irqsoff_tracer_call,
157 #endif /* CONFIG_FUNCTION_TRACER */
159 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
160 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
164 if (!(bit & TRACE_DISPLAY_GRAPH))
167 if (!(is_graph() ^ set))
170 stop_irqsoff_tracer(irqsoff_trace, !set);
172 for_each_possible_cpu(cpu)
173 per_cpu(tracing_cpu, cpu) = 0;
175 tracing_max_latency = 0;
176 tracing_reset_online_cpus(irqsoff_trace);
178 return start_irqsoff_tracer(irqsoff_trace, set);
181 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
183 struct trace_array *tr = irqsoff_trace;
184 struct trace_array_cpu *data;
189 if (!func_prolog_dec(tr, &data, &flags))
192 pc = preempt_count();
193 ret = __trace_graph_entry(tr, trace, flags, pc);
194 atomic_dec(&data->disabled);
199 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
201 struct trace_array *tr = irqsoff_trace;
202 struct trace_array_cpu *data;
206 if (!func_prolog_dec(tr, &data, &flags))
209 pc = preempt_count();
210 __trace_graph_return(tr, trace, flags, pc);
211 atomic_dec(&data->disabled);
214 static void irqsoff_trace_open(struct trace_iterator *iter)
217 graph_trace_open(iter);
221 static void irqsoff_trace_close(struct trace_iterator *iter)
224 graph_trace_close(iter);
227 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
228 TRACE_GRAPH_PRINT_PROC)
230 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
233 * In graph mode call the graph tracer output function,
234 * otherwise go with the TRACE_FN event handler
237 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
239 return TRACE_TYPE_UNHANDLED;
242 static void irqsoff_print_header(struct seq_file *s)
245 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
247 trace_default_header(s);
251 __trace_function(struct trace_array *tr,
252 unsigned long ip, unsigned long parent_ip,
253 unsigned long flags, int pc)
256 trace_graph_function(tr, ip, parent_ip, flags, pc);
258 trace_function(tr, ip, parent_ip, flags, pc);
262 #define __trace_function trace_function
264 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
269 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
274 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
276 return TRACE_TYPE_UNHANDLED;
279 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
280 static void irqsoff_print_header(struct seq_file *s) { }
281 static void irqsoff_trace_open(struct trace_iterator *iter) { }
282 static void irqsoff_trace_close(struct trace_iterator *iter) { }
283 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
286 * Should this new latency be reported/recorded?
288 static int report_latency(cycle_t delta)
290 if (tracing_thresh) {
291 if (delta < tracing_thresh)
294 if (delta <= tracing_max_latency)
301 check_critical_timing(struct trace_array *tr,
302 struct trace_array_cpu *data,
303 unsigned long parent_ip,
306 cycle_t T0, T1, delta;
310 T0 = data->preempt_timestamp;
311 T1 = ftrace_now(cpu);
314 local_save_flags(flags);
316 pc = preempt_count();
318 if (!report_latency(delta))
321 spin_lock_irqsave(&max_trace_lock, flags);
323 /* check if we are still the max latency */
324 if (!report_latency(delta))
327 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
328 /* Skip 5 functions to get to the irq/preempt enable function */
329 __trace_stack(tr, flags, 5, pc);
331 if (data->critical_sequence != max_sequence)
334 data->critical_end = parent_ip;
336 if (likely(!is_tracing_stopped())) {
337 tracing_max_latency = delta;
338 update_max_tr_single(tr, current, cpu);
344 spin_unlock_irqrestore(&max_trace_lock, flags);
347 data->critical_sequence = max_sequence;
348 data->preempt_timestamp = ftrace_now(cpu);
349 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
353 start_critical_timing(unsigned long ip, unsigned long parent_ip)
356 struct trace_array *tr = irqsoff_trace;
357 struct trace_array_cpu *data;
360 if (likely(!tracer_enabled))
363 cpu = raw_smp_processor_id();
365 if (per_cpu(tracing_cpu, cpu))
368 data = tr->data[cpu];
370 if (unlikely(!data) || atomic_read(&data->disabled))
373 atomic_inc(&data->disabled);
375 data->critical_sequence = max_sequence;
376 data->preempt_timestamp = ftrace_now(cpu);
377 data->critical_start = parent_ip ? : ip;
379 local_save_flags(flags);
381 __trace_function(tr, ip, parent_ip, flags, preempt_count());
383 per_cpu(tracing_cpu, cpu) = 1;
385 atomic_dec(&data->disabled);
389 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
392 struct trace_array *tr = irqsoff_trace;
393 struct trace_array_cpu *data;
396 cpu = raw_smp_processor_id();
397 /* Always clear the tracing cpu on stopping the trace */
398 if (unlikely(per_cpu(tracing_cpu, cpu)))
399 per_cpu(tracing_cpu, cpu) = 0;
406 data = tr->data[cpu];
408 if (unlikely(!data) ||
409 !data->critical_start || atomic_read(&data->disabled))
412 atomic_inc(&data->disabled);
414 local_save_flags(flags);
415 __trace_function(tr, ip, parent_ip, flags, preempt_count());
416 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
417 data->critical_start = 0;
418 atomic_dec(&data->disabled);
421 /* start and stop critical timings used to for stoppage (in idle) */
422 void start_critical_timings(void)
424 if (preempt_trace() || irq_trace())
425 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
427 EXPORT_SYMBOL_GPL(start_critical_timings);
429 void stop_critical_timings(void)
431 if (preempt_trace() || irq_trace())
432 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
434 EXPORT_SYMBOL_GPL(stop_critical_timings);
436 #ifdef CONFIG_IRQSOFF_TRACER
437 #ifdef CONFIG_PROVE_LOCKING
438 void time_hardirqs_on(unsigned long a0, unsigned long a1)
440 if (!preempt_trace() && irq_trace())
441 stop_critical_timing(a0, a1);
444 void time_hardirqs_off(unsigned long a0, unsigned long a1)
446 if (!preempt_trace() && irq_trace())
447 start_critical_timing(a0, a1);
450 #else /* !CONFIG_PROVE_LOCKING */
456 void trace_softirqs_on(unsigned long ip)
460 void trace_softirqs_off(unsigned long ip)
464 inline void print_irqtrace_events(struct task_struct *curr)
469 * We are only interested in hardirq on/off events:
471 void trace_hardirqs_on(void)
473 if (!preempt_trace() && irq_trace())
474 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
476 EXPORT_SYMBOL(trace_hardirqs_on);
478 void trace_hardirqs_off(void)
480 if (!preempt_trace() && irq_trace())
481 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
483 EXPORT_SYMBOL(trace_hardirqs_off);
485 void trace_hardirqs_on_caller(unsigned long caller_addr)
487 if (!preempt_trace() && irq_trace())
488 stop_critical_timing(CALLER_ADDR0, caller_addr);
490 EXPORT_SYMBOL(trace_hardirqs_on_caller);
492 void trace_hardirqs_off_caller(unsigned long caller_addr)
494 if (!preempt_trace() && irq_trace())
495 start_critical_timing(CALLER_ADDR0, caller_addr);
497 EXPORT_SYMBOL(trace_hardirqs_off_caller);
499 #endif /* CONFIG_PROVE_LOCKING */
500 #endif /* CONFIG_IRQSOFF_TRACER */
502 #ifdef CONFIG_PREEMPT_TRACER
503 void trace_preempt_on(unsigned long a0, unsigned long a1)
506 stop_critical_timing(a0, a1);
509 void trace_preempt_off(unsigned long a0, unsigned long a1)
512 start_critical_timing(a0, a1);
514 #endif /* CONFIG_PREEMPT_TRACER */
516 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
521 ret = register_ftrace_function(&trace_ops);
523 ret = register_ftrace_graph(&irqsoff_graph_return,
524 &irqsoff_graph_entry);
526 if (!ret && tracing_is_enabled())
534 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
539 unregister_ftrace_function(&trace_ops);
541 unregister_ftrace_graph();
544 static void __irqsoff_tracer_init(struct trace_array *tr)
546 save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
547 trace_flags |= TRACE_ITER_LATENCY_FMT;
549 tracing_max_latency = 0;
551 /* make sure that the tracer is visible */
553 tracing_reset_online_cpus(tr);
555 if (start_irqsoff_tracer(tr, is_graph()))
556 printk(KERN_ERR "failed to start irqsoff tracer\n");
559 static void irqsoff_tracer_reset(struct trace_array *tr)
561 stop_irqsoff_tracer(tr, is_graph());
564 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
567 static void irqsoff_tracer_start(struct trace_array *tr)
572 static void irqsoff_tracer_stop(struct trace_array *tr)
577 #ifdef CONFIG_IRQSOFF_TRACER
578 static int irqsoff_tracer_init(struct trace_array *tr)
580 trace_type = TRACER_IRQS_OFF;
582 __irqsoff_tracer_init(tr);
585 static struct tracer irqsoff_tracer __read_mostly =
588 .init = irqsoff_tracer_init,
589 .reset = irqsoff_tracer_reset,
590 .start = irqsoff_tracer_start,
591 .stop = irqsoff_tracer_stop,
593 .print_header = irqsoff_print_header,
594 .print_line = irqsoff_print_line,
595 .flags = &tracer_flags,
596 .set_flag = irqsoff_set_flag,
597 #ifdef CONFIG_FTRACE_SELFTEST
598 .selftest = trace_selftest_startup_irqsoff,
600 .open = irqsoff_trace_open,
601 .close = irqsoff_trace_close,
604 # define register_irqsoff(trace) register_tracer(&trace)
606 # define register_irqsoff(trace) do { } while (0)
609 #ifdef CONFIG_PREEMPT_TRACER
610 static int preemptoff_tracer_init(struct trace_array *tr)
612 trace_type = TRACER_PREEMPT_OFF;
614 __irqsoff_tracer_init(tr);
618 static struct tracer preemptoff_tracer __read_mostly =
620 .name = "preemptoff",
621 .init = preemptoff_tracer_init,
622 .reset = irqsoff_tracer_reset,
623 .start = irqsoff_tracer_start,
624 .stop = irqsoff_tracer_stop,
626 .print_header = irqsoff_print_header,
627 .print_line = irqsoff_print_line,
628 .flags = &tracer_flags,
629 .set_flag = irqsoff_set_flag,
630 #ifdef CONFIG_FTRACE_SELFTEST
631 .selftest = trace_selftest_startup_preemptoff,
633 .open = irqsoff_trace_open,
634 .close = irqsoff_trace_close,
637 # define register_preemptoff(trace) register_tracer(&trace)
639 # define register_preemptoff(trace) do { } while (0)
642 #if defined(CONFIG_IRQSOFF_TRACER) && \
643 defined(CONFIG_PREEMPT_TRACER)
645 static int preemptirqsoff_tracer_init(struct trace_array *tr)
647 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
649 __irqsoff_tracer_init(tr);
653 static struct tracer preemptirqsoff_tracer __read_mostly =
655 .name = "preemptirqsoff",
656 .init = preemptirqsoff_tracer_init,
657 .reset = irqsoff_tracer_reset,
658 .start = irqsoff_tracer_start,
659 .stop = irqsoff_tracer_stop,
661 .print_header = irqsoff_print_header,
662 .print_line = irqsoff_print_line,
663 .flags = &tracer_flags,
664 .set_flag = irqsoff_set_flag,
665 #ifdef CONFIG_FTRACE_SELFTEST
666 .selftest = trace_selftest_startup_preemptirqsoff,
668 .open = irqsoff_trace_open,
669 .close = irqsoff_trace_close,
673 # define register_preemptirqsoff(trace) register_tracer(&trace)
675 # define register_preemptirqsoff(trace) do { } while (0)
678 __init static int init_irqsoff_tracer(void)
680 register_irqsoff(irqsoff_tracer);
681 register_preemptoff(preemptoff_tracer);
682 register_preemptirqsoff(preemptirqsoff_tracer);
686 device_initcall(init_irqsoff_tracer);