1 // SPDX-License-Identifier: GPL-2.0
3 * OS Noise Tracer: computes the OS Noise suffered by a running thread.
4 * Timerlat Tracer: measures the wakeup latency of a timer triggered IRQ and thread.
6 * Based on "hwlat_detector" tracer by:
7 * Copyright (C) 2008-2009 Jon Masters, Red Hat, Inc. <jcm@redhat.com>
8 * Copyright (C) 2013-2016 Steven Rostedt, Red Hat, Inc. <srostedt@redhat.com>
9 * With feedback from Clark Williams <williams@redhat.com>
11 * And also based on the rtsl tracer presented on:
12 * DE OLIVEIRA, Daniel Bristot, et al. Demystifying the real-time linux
13 * scheduling latency. In: 32nd Euromicro Conference on Real-Time Systems
14 * (ECRTS 2020). Schloss Dagstuhl-Leibniz-Zentrum fur Informatik, 2020.
16 * Copyright (C) 2021 Daniel Bristot de Oliveira, Red Hat, Inc. <bristot@redhat.com>
19 #include <linux/kthread.h>
20 #include <linux/tracefs.h>
21 #include <linux/uaccess.h>
22 #include <linux/cpumask.h>
23 #include <linux/delay.h>
24 #include <linux/sched/clock.h>
25 #include <uapi/linux/sched/types.h>
26 #include <linux/sched.h>
29 #ifdef CONFIG_X86_LOCAL_APIC
30 #include <asm/trace/irq_vectors.h>
31 #undef TRACE_INCLUDE_PATH
32 #undef TRACE_INCLUDE_FILE
33 #endif /* CONFIG_X86_LOCAL_APIC */
35 #include <trace/events/irq.h>
36 #include <trace/events/sched.h>
38 #define CREATE_TRACE_POINTS
39 #include <trace/events/osnoise.h>
41 static struct trace_array *osnoise_trace;
46 #define BANNER "osnoise: "
47 #define DEFAULT_SAMPLE_PERIOD 1000000 /* 1s */
48 #define DEFAULT_SAMPLE_RUNTIME 1000000 /* 1s */
50 #define DEFAULT_TIMERLAT_PERIOD 1000 /* 1ms */
51 #define DEFAULT_TIMERLAT_PRIO 95 /* FIFO 95 */
71 #define THREAD_CONTEXT 1
73 * sofirq runtime info.
82 * thread runtime info.
91 * Runtime information: this structure saves the runtime information used by
92 * one sampling thread.
94 struct osnoise_variables {
95 struct task_struct *kthread;
100 struct osn_softirq softirq;
101 struct osn_thread thread;
106 * Per-cpu runtime information.
108 DEFINE_PER_CPU(struct osnoise_variables, per_cpu_osnoise_var);
111 * this_cpu_osn_var - Return the per-cpu osnoise_variables on its relative CPU
113 static inline struct osnoise_variables *this_cpu_osn_var(void)
115 return this_cpu_ptr(&per_cpu_osnoise_var);
118 #ifdef CONFIG_TIMERLAT_TRACER
120 * Runtime information for the timer mode.
122 struct timerlat_variables {
123 struct task_struct *kthread;
124 struct hrtimer timer;
131 DEFINE_PER_CPU(struct timerlat_variables, per_cpu_timerlat_var);
134 * this_cpu_tmr_var - Return the per-cpu timerlat_variables on its relative CPU
136 static inline struct timerlat_variables *this_cpu_tmr_var(void)
138 return this_cpu_ptr(&per_cpu_timerlat_var);
142 * tlat_var_reset - Reset the values of the given timerlat_variables
144 static inline void tlat_var_reset(void)
146 struct timerlat_variables *tlat_var;
149 * So far, all the values are initialized as 0, so
150 * zeroing the structure is perfect.
152 for_each_cpu(cpu, cpu_online_mask) {
153 tlat_var = per_cpu_ptr(&per_cpu_timerlat_var, cpu);
154 memset(tlat_var, 0, sizeof(*tlat_var));
157 #else /* CONFIG_TIMERLAT_TRACER */
158 #define tlat_var_reset() do {} while (0)
159 #endif /* CONFIG_TIMERLAT_TRACER */
162 * osn_var_reset - Reset the values of the given osnoise_variables
164 static inline void osn_var_reset(void)
166 struct osnoise_variables *osn_var;
170 * So far, all the values are initialized as 0, so
171 * zeroing the structure is perfect.
173 for_each_cpu(cpu, cpu_online_mask) {
174 osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu);
175 memset(osn_var, 0, sizeof(*osn_var));
180 * osn_var_reset_all - Reset the value of all per-cpu osnoise_variables
182 static inline void osn_var_reset_all(void)
189 * Tells NMIs to call back to the osnoise tracer to record timestamps.
191 bool trace_osnoise_callback_enabled;
194 * osnoise sample structure definition. Used to store the statistics of a
197 struct osnoise_sample {
198 u64 runtime; /* runtime */
199 u64 noise; /* noise */
200 u64 max_sample; /* max single noise sample */
201 int hw_count; /* # HW (incl. hypervisor) interference */
202 int nmi_count; /* # NMIs during this sample */
203 int irq_count; /* # IRQs during this sample */
204 int softirq_count; /* # softirqs during this sample */
205 int thread_count; /* # threads during this sample */
208 #ifdef CONFIG_TIMERLAT_TRACER
210 * timerlat sample structure definition. Used to store the statistics of
213 struct timerlat_sample {
214 u64 timer_latency; /* timer_latency */
215 unsigned int seqnum; /* unique sequence */
216 int context; /* timer context */
221 * Protect the interface.
223 struct mutex interface_lock;
228 static struct osnoise_data {
229 u64 sample_period; /* total sampling period */
230 u64 sample_runtime; /* active sampling portion of period */
231 u64 stop_tracing; /* stop trace in the internal operation (loop/irq) */
232 u64 stop_tracing_total; /* stop trace in the final operation (report/thread) */
233 #ifdef CONFIG_TIMERLAT_TRACER
234 u64 timerlat_period; /* timerlat period */
235 u64 print_stack; /* print IRQ stack if total > */
236 int timerlat_tracer; /* timerlat tracer */
238 bool tainted; /* infor users and developers about a problem */
240 .sample_period = DEFAULT_SAMPLE_PERIOD,
241 .sample_runtime = DEFAULT_SAMPLE_RUNTIME,
243 .stop_tracing_total = 0,
244 #ifdef CONFIG_TIMERLAT_TRACER
246 .timerlat_period = DEFAULT_TIMERLAT_PERIOD,
247 .timerlat_tracer = 0,
252 * Boolean variable used to inform that the tracer is currently sampling.
254 static bool osnoise_busy;
257 * Print the osnoise header info.
259 static void print_osnoise_headers(struct seq_file *s)
261 if (osnoise_data.tainted)
262 seq_puts(s, "# osnoise is tainted!\n");
264 seq_puts(s, "# _-----=> irqs-off\n");
265 seq_puts(s, "# / _----=> need-resched\n");
266 seq_puts(s, "# | / _---=> hardirq/softirq\n");
267 seq_puts(s, "# || / _--=> preempt-depth ");
268 seq_puts(s, " MAX\n");
270 seq_puts(s, "# || / ");
271 seq_puts(s, " SINGLE Interference counters:\n");
273 seq_puts(s, "# |||| RUNTIME ");
274 seq_puts(s, " NOISE %% OF CPU NOISE +-----------------------------+\n");
276 seq_puts(s, "# TASK-PID CPU# |||| TIMESTAMP IN US ");
277 seq_puts(s, " IN US AVAILABLE IN US HW NMI IRQ SIRQ THREAD\n");
279 seq_puts(s, "# | | | |||| | | ");
280 seq_puts(s, " | | | | | | | |\n");
284 * osnoise_taint - report an osnoise error.
286 #define osnoise_taint(msg) ({ \
287 struct trace_array *tr = osnoise_trace; \
289 trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, msg); \
290 osnoise_data.tainted = true; \
294 * Record an osnoise_sample into the tracer buffer.
296 static void trace_osnoise_sample(struct osnoise_sample *sample)
298 struct trace_array *tr = osnoise_trace;
299 struct trace_buffer *buffer = tr->array_buffer.buffer;
300 struct trace_event_call *call = &event_osnoise;
301 struct ring_buffer_event *event;
302 struct osnoise_entry *entry;
304 event = trace_buffer_lock_reserve(buffer, TRACE_OSNOISE, sizeof(*entry),
308 entry = ring_buffer_event_data(event);
309 entry->runtime = sample->runtime;
310 entry->noise = sample->noise;
311 entry->max_sample = sample->max_sample;
312 entry->hw_count = sample->hw_count;
313 entry->nmi_count = sample->nmi_count;
314 entry->irq_count = sample->irq_count;
315 entry->softirq_count = sample->softirq_count;
316 entry->thread_count = sample->thread_count;
318 if (!call_filter_check_discard(call, entry, buffer, event))
319 trace_buffer_unlock_commit_nostack(buffer, event);
322 #ifdef CONFIG_TIMERLAT_TRACER
324 * Print the timerlat header info.
326 static void print_timerlat_headers(struct seq_file *s)
328 seq_puts(s, "# _-----=> irqs-off\n");
329 seq_puts(s, "# / _----=> need-resched\n");
330 seq_puts(s, "# | / _---=> hardirq/softirq\n");
331 seq_puts(s, "# || / _--=> preempt-depth\n");
332 seq_puts(s, "# || /\n");
333 seq_puts(s, "# |||| ACTIVATION\n");
334 seq_puts(s, "# TASK-PID CPU# |||| TIMESTAMP ID ");
335 seq_puts(s, " CONTEXT LATENCY\n");
336 seq_puts(s, "# | | | |||| | | ");
337 seq_puts(s, " | |\n");
341 * Record an timerlat_sample into the tracer buffer.
343 static void trace_timerlat_sample(struct timerlat_sample *sample)
345 struct trace_array *tr = osnoise_trace;
346 struct trace_event_call *call = &event_osnoise;
347 struct trace_buffer *buffer = tr->array_buffer.buffer;
348 struct ring_buffer_event *event;
349 struct timerlat_entry *entry;
351 event = trace_buffer_lock_reserve(buffer, TRACE_TIMERLAT, sizeof(*entry),
355 entry = ring_buffer_event_data(event);
356 entry->seqnum = sample->seqnum;
357 entry->context = sample->context;
358 entry->timer_latency = sample->timer_latency;
360 if (!call_filter_check_discard(call, entry, buffer, event))
361 trace_buffer_unlock_commit_nostack(buffer, event);
364 #ifdef CONFIG_STACKTRACE
366 #define MAX_CALLS 256
369 * Stack trace will take place only at IRQ level, so, no need
370 * to control nesting here.
375 unsigned long calls[MAX_CALLS];
378 static DEFINE_PER_CPU(struct trace_stack, trace_stack);
381 * timerlat_save_stack - save a stack trace without printing
383 * Save the current stack trace without printing. The
384 * stack will be printed later, after the end of the measurement.
386 static void timerlat_save_stack(int skip)
388 unsigned int size, nr_entries;
389 struct trace_stack *fstack;
391 fstack = this_cpu_ptr(&trace_stack);
393 size = ARRAY_SIZE(fstack->calls);
395 nr_entries = stack_trace_save(fstack->calls, size, skip);
397 fstack->stack_size = nr_entries * sizeof(unsigned long);
398 fstack->nr_entries = nr_entries;
404 * timerlat_dump_stack - dump a stack trace previously saved
406 * Dump a saved stack trace into the trace buffer.
408 static void timerlat_dump_stack(void)
410 struct trace_event_call *call = &event_osnoise;
411 struct trace_array *tr = osnoise_trace;
412 struct trace_buffer *buffer = tr->array_buffer.buffer;
413 struct ring_buffer_event *event;
414 struct trace_stack *fstack;
415 struct stack_entry *entry;
418 preempt_disable_notrace();
419 fstack = this_cpu_ptr(&trace_stack);
420 size = fstack->stack_size;
422 event = trace_buffer_lock_reserve(buffer, TRACE_STACK, sizeof(*entry) + size,
427 entry = ring_buffer_event_data(event);
429 memcpy(&entry->caller, fstack->calls, size);
430 entry->size = fstack->nr_entries;
432 if (!call_filter_check_discard(call, entry, buffer, event))
433 trace_buffer_unlock_commit_nostack(buffer, event);
436 preempt_enable_notrace();
439 #define timerlat_dump_stack() do {} while (0)
440 #define timerlat_save_stack(a) do {} while (0)
441 #endif /* CONFIG_STACKTRACE */
442 #endif /* CONFIG_TIMERLAT_TRACER */
445 * Macros to encapsulate the time capturing infrastructure.
447 #define time_get() trace_clock_local()
448 #define time_to_us(x) div_u64(x, 1000)
449 #define time_sub(a, b) ((a) - (b))
452 * cond_move_irq_delta_start - Forward the delta_start of a running IRQ
454 * If an IRQ is preempted by an NMI, its delta_start is pushed forward
455 * to discount the NMI interference.
457 * See get_int_safe_duration().
460 cond_move_irq_delta_start(struct osnoise_variables *osn_var, u64 duration)
462 if (osn_var->irq.delta_start)
463 osn_var->irq.delta_start += duration;
466 #ifndef CONFIG_PREEMPT_RT
468 * cond_move_softirq_delta_start - Forward the delta_start of a running softirq.
470 * If a softirq is preempted by an IRQ or NMI, its delta_start is pushed
471 * forward to discount the interference.
473 * See get_int_safe_duration().
476 cond_move_softirq_delta_start(struct osnoise_variables *osn_var, u64 duration)
478 if (osn_var->softirq.delta_start)
479 osn_var->softirq.delta_start += duration;
481 #else /* CONFIG_PREEMPT_RT */
482 #define cond_move_softirq_delta_start(osn_var, duration) do {} while (0)
486 * cond_move_thread_delta_start - Forward the delta_start of a running thread
488 * If a noisy thread is preempted by an softirq, IRQ or NMI, its delta_start
489 * is pushed forward to discount the interference.
491 * See get_int_safe_duration().
494 cond_move_thread_delta_start(struct osnoise_variables *osn_var, u64 duration)
496 if (osn_var->thread.delta_start)
497 osn_var->thread.delta_start += duration;
501 * get_int_safe_duration - Get the duration of a window
503 * The irq, softirq and thread varaibles need to have its duration without
504 * the interference from higher priority interrupts. Instead of keeping a
505 * variable to discount the interrupt interference from these variables, the
506 * starting time of these variables are pushed forward with the interrupt's
507 * duration. In this way, a single variable is used to:
509 * - Know if a given window is being measured.
510 * - Account its duration.
511 * - Discount the interference.
513 * To avoid getting inconsistent values, e.g.,:
517 * delta_start -= int duration;
519 * duration = now - delta_start;
521 * result: negative duration if the variable duration before the
522 * interrupt was smaller than the interrupt execution.
524 * A counter of interrupts is used. If the counter increased, try
525 * to capture an interference safe duration.
528 get_int_safe_duration(struct osnoise_variables *osn_var, u64 *delta_start)
530 u64 int_counter, now;
534 int_counter = local_read(&osn_var->int_counter);
535 /* synchronize with interrupts */
539 duration = (now - *delta_start);
541 /* synchronize with interrupts */
543 } while (int_counter != local_read(&osn_var->int_counter));
546 * This is an evidence of race conditions that cause
547 * a value to be "discounted" too much.
550 osnoise_taint("Negative duration!\n");
559 * set_int_safe_time - Save the current time on *time, aware of interference
561 * Get the time, taking into consideration a possible interference from
562 * higher priority interrupts.
564 * See get_int_safe_duration() for an explanation.
567 set_int_safe_time(struct osnoise_variables *osn_var, u64 *time)
572 int_counter = local_read(&osn_var->int_counter);
573 /* synchronize with interrupts */
578 /* synchronize with interrupts */
580 } while (int_counter != local_read(&osn_var->int_counter));
585 #ifdef CONFIG_TIMERLAT_TRACER
587 * copy_int_safe_time - Copy *src into *desc aware of interference
590 copy_int_safe_time(struct osnoise_variables *osn_var, u64 *dst, u64 *src)
595 int_counter = local_read(&osn_var->int_counter);
596 /* synchronize with interrupts */
601 /* synchronize with interrupts */
603 } while (int_counter != local_read(&osn_var->int_counter));
607 #endif /* CONFIG_TIMERLAT_TRACER */
610 * trace_osnoise_callback - NMI entry/exit callback
612 * This function is called at the entry and exit NMI code. The bool enter
613 * distinguishes between either case. This function is used to note a NMI
614 * occurrence, compute the noise caused by the NMI, and to remove the noise
615 * it is potentially causing on other interference variables.
617 void trace_osnoise_callback(bool enter)
619 struct osnoise_variables *osn_var = this_cpu_osn_var();
622 if (!osn_var->sampling)
626 * Currently trace_clock_local() calls sched_clock() and the
627 * generic version is not NMI safe.
629 if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
631 osn_var->nmi.delta_start = time_get();
632 local_inc(&osn_var->int_counter);
634 duration = time_get() - osn_var->nmi.delta_start;
636 trace_nmi_noise(osn_var->nmi.delta_start, duration);
638 cond_move_irq_delta_start(osn_var, duration);
639 cond_move_softirq_delta_start(osn_var, duration);
640 cond_move_thread_delta_start(osn_var, duration);
645 osn_var->nmi.count++;
649 * osnoise_trace_irq_entry - Note the starting of an IRQ
651 * Save the starting time of an IRQ. As IRQs are non-preemptive to other IRQs,
652 * it is safe to use a single variable (ons_var->irq) to save the statistics.
653 * The arrival_time is used to report... the arrival time. The delta_start
654 * is used to compute the duration at the IRQ exit handler. See
655 * cond_move_irq_delta_start().
657 void osnoise_trace_irq_entry(int id)
659 struct osnoise_variables *osn_var = this_cpu_osn_var();
661 if (!osn_var->sampling)
664 * This value will be used in the report, but not to compute
665 * the execution time, so it is safe to get it unsafe.
667 osn_var->irq.arrival_time = time_get();
668 set_int_safe_time(osn_var, &osn_var->irq.delta_start);
669 osn_var->irq.count++;
671 local_inc(&osn_var->int_counter);
675 * osnoise_irq_exit - Note the end of an IRQ, sava data and trace
677 * Computes the duration of the IRQ noise, and trace it. Also discounts the
678 * interference from other sources of noise could be currently being accounted.
680 void osnoise_trace_irq_exit(int id, const char *desc)
682 struct osnoise_variables *osn_var = this_cpu_osn_var();
685 if (!osn_var->sampling)
688 duration = get_int_safe_duration(osn_var, &osn_var->irq.delta_start);
689 trace_irq_noise(id, desc, osn_var->irq.arrival_time, duration);
690 osn_var->irq.arrival_time = 0;
691 cond_move_softirq_delta_start(osn_var, duration);
692 cond_move_thread_delta_start(osn_var, duration);
696 * trace_irqentry_callback - Callback to the irq:irq_entry traceevent
698 * Used to note the starting of an IRQ occurece.
700 static void trace_irqentry_callback(void *data, int irq,
701 struct irqaction *action)
703 osnoise_trace_irq_entry(irq);
707 * trace_irqexit_callback - Callback to the irq:irq_exit traceevent
709 * Used to note the end of an IRQ occurece.
711 static void trace_irqexit_callback(void *data, int irq,
712 struct irqaction *action, int ret)
714 osnoise_trace_irq_exit(irq, action->name);
718 * arch specific register function.
720 int __weak osnoise_arch_register(void)
726 * arch specific unregister function.
728 void __weak osnoise_arch_unregister(void)
734 * hook_irq_events - Hook IRQ handling events
736 * This function hooks the IRQ related callbacks to the respective trace
739 static int hook_irq_events(void)
743 ret = register_trace_irq_handler_entry(trace_irqentry_callback, NULL);
747 ret = register_trace_irq_handler_exit(trace_irqexit_callback, NULL);
749 goto out_unregister_entry;
751 ret = osnoise_arch_register();
758 unregister_trace_irq_handler_exit(trace_irqexit_callback, NULL);
759 out_unregister_entry:
760 unregister_trace_irq_handler_entry(trace_irqentry_callback, NULL);
766 * unhook_irq_events - Unhook IRQ handling events
768 * This function unhooks the IRQ related callbacks to the respective trace
771 static void unhook_irq_events(void)
773 osnoise_arch_unregister();
774 unregister_trace_irq_handler_exit(trace_irqexit_callback, NULL);
775 unregister_trace_irq_handler_entry(trace_irqentry_callback, NULL);
778 #ifndef CONFIG_PREEMPT_RT
780 * trace_softirq_entry_callback - Note the starting of a softirq
782 * Save the starting time of a softirq. As softirqs are non-preemptive to
783 * other softirqs, it is safe to use a single variable (ons_var->softirq)
784 * to save the statistics. The arrival_time is used to report... the
785 * arrival time. The delta_start is used to compute the duration at the
786 * softirq exit handler. See cond_move_softirq_delta_start().
788 static void trace_softirq_entry_callback(void *data, unsigned int vec_nr)
790 struct osnoise_variables *osn_var = this_cpu_osn_var();
792 if (!osn_var->sampling)
795 * This value will be used in the report, but not to compute
796 * the execution time, so it is safe to get it unsafe.
798 osn_var->softirq.arrival_time = time_get();
799 set_int_safe_time(osn_var, &osn_var->softirq.delta_start);
800 osn_var->softirq.count++;
802 local_inc(&osn_var->int_counter);
806 * trace_softirq_exit_callback - Note the end of an softirq
808 * Computes the duration of the softirq noise, and trace it. Also discounts the
809 * interference from other sources of noise could be currently being accounted.
811 static void trace_softirq_exit_callback(void *data, unsigned int vec_nr)
813 struct osnoise_variables *osn_var = this_cpu_osn_var();
816 if (!osn_var->sampling)
819 #ifdef CONFIG_TIMERLAT_TRACER
821 * If the timerlat is enabled, but the irq handler did
822 * not run yet enabling timerlat_tracer, do not trace.
824 if (unlikely(osnoise_data.timerlat_tracer)) {
825 struct timerlat_variables *tlat_var;
826 tlat_var = this_cpu_tmr_var();
827 if (!tlat_var->tracing_thread) {
828 osn_var->softirq.arrival_time = 0;
829 osn_var->softirq.delta_start = 0;
835 duration = get_int_safe_duration(osn_var, &osn_var->softirq.delta_start);
836 trace_softirq_noise(vec_nr, osn_var->softirq.arrival_time, duration);
837 cond_move_thread_delta_start(osn_var, duration);
838 osn_var->softirq.arrival_time = 0;
842 * hook_softirq_events - Hook softirq handling events
844 * This function hooks the softirq related callbacks to the respective trace
847 static int hook_softirq_events(void)
851 ret = register_trace_softirq_entry(trace_softirq_entry_callback, NULL);
855 ret = register_trace_softirq_exit(trace_softirq_exit_callback, NULL);
857 goto out_unreg_entry;
862 unregister_trace_softirq_entry(trace_softirq_entry_callback, NULL);
868 * unhook_softirq_events - Unhook softirq handling events
870 * This function hooks the softirq related callbacks to the respective trace
873 static void unhook_softirq_events(void)
875 unregister_trace_softirq_entry(trace_softirq_entry_callback, NULL);
876 unregister_trace_softirq_exit(trace_softirq_exit_callback, NULL);
878 #else /* CONFIG_PREEMPT_RT */
880 * softirq are threads on the PREEMPT_RT mode.
882 static int hook_softirq_events(void)
886 static void unhook_softirq_events(void)
892 * thread_entry - Record the starting of a thread noise window
894 * It saves the context switch time for a noisy thread, and increments
895 * the interference counters.
898 thread_entry(struct osnoise_variables *osn_var, struct task_struct *t)
900 if (!osn_var->sampling)
903 * The arrival time will be used in the report, but not to compute
904 * the execution time, so it is safe to get it unsafe.
906 osn_var->thread.arrival_time = time_get();
908 set_int_safe_time(osn_var, &osn_var->thread.delta_start);
910 osn_var->thread.count++;
911 local_inc(&osn_var->int_counter);
915 * thread_exit - Report the end of a thread noise window
917 * It computes the total noise from a thread, tracing if needed.
920 thread_exit(struct osnoise_variables *osn_var, struct task_struct *t)
924 if (!osn_var->sampling)
927 #ifdef CONFIG_TIMERLAT_TRACER
928 if (osnoise_data.timerlat_tracer) {
929 struct timerlat_variables *tlat_var;
930 tlat_var = this_cpu_tmr_var();
931 if (!tlat_var->tracing_thread) {
932 osn_var->thread.delta_start = 0;
933 osn_var->thread.arrival_time = 0;
939 duration = get_int_safe_duration(osn_var, &osn_var->thread.delta_start);
941 trace_thread_noise(t, osn_var->thread.arrival_time, duration);
943 osn_var->thread.arrival_time = 0;
947 * trace_sched_switch - sched:sched_switch trace event handler
949 * This function is hooked to the sched:sched_switch trace event, and it is
950 * used to record the beginning and to report the end of a thread noise window.
953 trace_sched_switch_callback(void *data, bool preempt, struct task_struct *p,
954 struct task_struct *n)
956 struct osnoise_variables *osn_var = this_cpu_osn_var();
958 if (p->pid != osn_var->pid)
959 thread_exit(osn_var, p);
961 if (n->pid != osn_var->pid)
962 thread_entry(osn_var, n);
966 * hook_thread_events - Hook the insturmentation for thread noise
968 * Hook the osnoise tracer callbacks to handle the noise from other
969 * threads on the necessary kernel events.
971 static int hook_thread_events(void)
975 ret = register_trace_sched_switch(trace_sched_switch_callback, NULL);
983 * unhook_thread_events - *nhook the insturmentation for thread noise
985 * Unook the osnoise tracer callbacks to handle the noise from other
986 * threads on the necessary kernel events.
988 static void unhook_thread_events(void)
990 unregister_trace_sched_switch(trace_sched_switch_callback, NULL);
994 * save_osn_sample_stats - Save the osnoise_sample statistics
996 * Save the osnoise_sample statistics before the sampling phase. These
997 * values will be used later to compute the diff betwneen the statistics
998 * before and after the osnoise sampling.
1001 save_osn_sample_stats(struct osnoise_variables *osn_var, struct osnoise_sample *s)
1003 s->nmi_count = osn_var->nmi.count;
1004 s->irq_count = osn_var->irq.count;
1005 s->softirq_count = osn_var->softirq.count;
1006 s->thread_count = osn_var->thread.count;
1010 * diff_osn_sample_stats - Compute the osnoise_sample statistics
1012 * After a sample period, compute the difference on the osnoise_sample
1013 * statistics. The struct osnoise_sample *s contains the statistics saved via
1014 * save_osn_sample_stats() before the osnoise sampling.
1017 diff_osn_sample_stats(struct osnoise_variables *osn_var, struct osnoise_sample *s)
1019 s->nmi_count = osn_var->nmi.count - s->nmi_count;
1020 s->irq_count = osn_var->irq.count - s->irq_count;
1021 s->softirq_count = osn_var->softirq.count - s->softirq_count;
1022 s->thread_count = osn_var->thread.count - s->thread_count;
1026 * osnoise_stop_tracing - Stop tracing and the tracer.
1028 static void osnoise_stop_tracing(void)
1030 struct trace_array *tr = osnoise_trace;
1031 tracer_tracing_off(tr);
1035 * run_osnoise - Sample the time and look for osnoise
1037 * Used to capture the time, looking for potential osnoise latency repeatedly.
1038 * Different from hwlat_detector, it is called with preemption and interrupts
1039 * enabled. This allows irqs, softirqs and threads to run, interfering on the
1040 * osnoise sampling thread, as they would do with a regular thread.
1042 static int run_osnoise(void)
1044 struct osnoise_variables *osn_var = this_cpu_osn_var();
1045 struct trace_array *tr = osnoise_trace;
1046 u64 start, sample, last_sample;
1047 u64 last_int_count, int_count;
1048 s64 noise = 0, max_noise = 0;
1049 s64 total, last_total = 0;
1050 struct osnoise_sample s;
1051 unsigned int threshold;
1052 u64 runtime, stop_in;
1058 * Considers the current thread as the workload.
1060 osn_var->pid = current->pid;
1063 * Save the current stats for the diff
1065 save_osn_sample_stats(osn_var, &s);
1068 * if threshold is 0, use the default value of 5 us.
1070 threshold = tracing_thresh ? : 5000;
1073 * Make sure NMIs see sampling first
1075 osn_var->sampling = true;
1079 * Transform the *_us config to nanoseconds to avoid the
1080 * division on the main loop.
1082 runtime = osnoise_data.sample_runtime * NSEC_PER_USEC;
1083 stop_in = osnoise_data.stop_tracing * NSEC_PER_USEC;
1093 last_int_count = set_int_safe_time(osn_var, &last_sample);
1099 int_count = set_int_safe_time(osn_var, &sample);
1101 noise = time_sub(sample, last_sample);
1104 * This shouldn't happen.
1107 osnoise_taint("negative noise!");
1114 total = time_sub(sample, start);
1117 * Check for possible overflows.
1119 if (total < last_total) {
1120 osnoise_taint("total overflow!");
1126 if (noise >= threshold) {
1127 int interference = int_count - last_int_count;
1129 if (noise > max_noise)
1137 trace_sample_threshold(last_sample, noise, interference);
1139 if (osnoise_data.stop_tracing)
1140 if (noise > stop_in)
1141 osnoise_stop_tracing();
1145 * For the non-preemptive kernel config: let threads runs, if
1150 last_sample = sample;
1151 last_int_count = int_count;
1153 } while (total < runtime && !kthread_should_stop());
1156 * Finish the above in the view for interrupts.
1160 osn_var->sampling = false;
1163 * Make sure sampling data is no longer updated.
1170 s.noise = time_to_us(sum_noise);
1171 s.runtime = time_to_us(total);
1172 s.max_sample = time_to_us(max_noise);
1173 s.hw_count = hw_count;
1175 /* Save interference stats info */
1176 diff_osn_sample_stats(osn_var, &s);
1178 trace_osnoise_sample(&s);
1180 /* Keep a running maximum ever recorded osnoise "latency" */
1181 if (max_noise > tr->max_latency) {
1182 tr->max_latency = max_noise;
1183 latency_fsnotify(tr);
1186 if (osnoise_data.stop_tracing_total)
1187 if (s.noise > osnoise_data.stop_tracing_total)
1188 osnoise_stop_tracing();
1195 static struct cpumask osnoise_cpumask;
1196 static struct cpumask save_cpumask;
1199 * osnoise_main - The osnoise detection kernel thread
1201 * Calls run_osnoise() function to measure the osnoise for the configured runtime,
1204 static int osnoise_main(void *data)
1208 while (!kthread_should_stop()) {
1212 mutex_lock(&interface_lock);
1213 interval = osnoise_data.sample_period - osnoise_data.sample_runtime;
1214 mutex_unlock(&interface_lock);
1216 do_div(interval, USEC_PER_MSEC);
1219 * differently from hwlat_detector, the osnoise tracer can run
1220 * without a pause because preemption is on.
1223 /* Let synchronize_rcu_tasks() make progress */
1224 cond_resched_tasks_rcu_qs();
1228 if (msleep_interruptible(interval))
1235 #ifdef CONFIG_TIMERLAT_TRACER
1237 * timerlat_irq - hrtimer handler for timerlat.
1239 static enum hrtimer_restart timerlat_irq(struct hrtimer *timer)
1241 struct osnoise_variables *osn_var = this_cpu_osn_var();
1242 struct trace_array *tr = osnoise_trace;
1243 struct timerlat_variables *tlat;
1244 struct timerlat_sample s;
1249 * I am not sure if the timer was armed for this CPU. So, get
1250 * the timerlat struct from the timer itself, not from this
1253 tlat = container_of(timer, struct timerlat_variables, timer);
1255 now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer));
1258 * Enable the osnoise: events for thread an softirq.
1260 tlat->tracing_thread = true;
1262 osn_var->thread.arrival_time = time_get();
1265 * A hardirq is running: the timer IRQ. It is for sure preempting
1266 * a thread, and potentially preempting a softirq.
1268 * At this point, it is not interesting to know the duration of the
1269 * preempted thread (and maybe softirq), but how much time they will
1270 * delay the beginning of the execution of the timer thread.
1272 * To get the correct (net) delay added by the softirq, its delta_start
1273 * is set as the IRQ one. In this way, at the return of the IRQ, the delta
1274 * start of the sofitrq will be zeroed, accounting then only the time
1277 * The thread follows the same principle. However, if a softirq is
1278 * running, the thread needs to receive the softirq delta_start. The
1279 * reason being is that the softirq will be the last to be unfolded,
1280 * resseting the thread delay to zero.
1282 #ifndef CONFIG_PREEMPT_RT
1283 if (osn_var->softirq.delta_start) {
1284 copy_int_safe_time(osn_var, &osn_var->thread.delta_start,
1285 &osn_var->softirq.delta_start);
1287 copy_int_safe_time(osn_var, &osn_var->softirq.delta_start,
1288 &osn_var->irq.delta_start);
1290 copy_int_safe_time(osn_var, &osn_var->thread.delta_start,
1291 &osn_var->irq.delta_start);
1293 #else /* CONFIG_PREEMPT_RT */
1295 * The sofirqs run as threads on RT, so there is not need
1296 * to keep track of it.
1298 copy_int_safe_time(osn_var, &osn_var->thread.delta_start, &osn_var->irq.delta_start);
1299 #endif /* CONFIG_PREEMPT_RT */
1302 * Compute the current time with the expected time.
1304 diff = now - tlat->abs_period;
1307 s.seqnum = tlat->count;
1308 s.timer_latency = diff;
1309 s.context = IRQ_CONTEXT;
1311 trace_timerlat_sample(&s);
1313 /* Keep a running maximum ever recorded os noise "latency" */
1314 if (diff > tr->max_latency) {
1315 tr->max_latency = diff;
1316 latency_fsnotify(tr);
1319 if (osnoise_data.stop_tracing)
1320 if (time_to_us(diff) >= osnoise_data.stop_tracing)
1321 osnoise_stop_tracing();
1323 wake_up_process(tlat->kthread);
1325 if (osnoise_data.print_stack)
1326 timerlat_save_stack(0);
1328 return HRTIMER_NORESTART;
1332 * wait_next_period - Wait for the next period for timerlat
1334 static int wait_next_period(struct timerlat_variables *tlat)
1336 ktime_t next_abs_period, now;
1337 u64 rel_period = osnoise_data.timerlat_period * 1000;
1339 now = hrtimer_cb_get_time(&tlat->timer);
1340 next_abs_period = ns_to_ktime(tlat->abs_period + rel_period);
1343 * Save the next abs_period.
1345 tlat->abs_period = (u64) ktime_to_ns(next_abs_period);
1348 * If the new abs_period is in the past, skip the activation.
1350 while (ktime_compare(now, next_abs_period) > 0) {
1351 next_abs_period = ns_to_ktime(tlat->abs_period + rel_period);
1352 tlat->abs_period = (u64) ktime_to_ns(next_abs_period);
1355 set_current_state(TASK_INTERRUPTIBLE);
1357 hrtimer_start(&tlat->timer, next_abs_period, HRTIMER_MODE_ABS_PINNED_HARD);
1363 * timerlat_main- Timerlat main
1365 static int timerlat_main(void *data)
1367 struct osnoise_variables *osn_var = this_cpu_osn_var();
1368 struct timerlat_variables *tlat = this_cpu_tmr_var();
1369 struct timerlat_sample s;
1370 struct sched_param sp;
1374 * Make the thread RT, that is how cyclictest is usually used.
1376 sp.sched_priority = DEFAULT_TIMERLAT_PRIO;
1377 sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
1380 tlat->tracing_thread = false;
1382 hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
1383 tlat->timer.function = timerlat_irq;
1384 tlat->kthread = current;
1385 osn_var->pid = current->pid;
1387 * Anotate the arrival time.
1389 tlat->abs_period = hrtimer_cb_get_time(&tlat->timer);
1391 wait_next_period(tlat);
1393 osn_var->sampling = 1;
1395 while (!kthread_should_stop()) {
1396 now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer));
1397 diff = now - tlat->abs_period;
1399 s.seqnum = tlat->count;
1400 s.timer_latency = diff;
1401 s.context = THREAD_CONTEXT;
1403 trace_timerlat_sample(&s);
1405 #ifdef CONFIG_STACKTRACE
1406 if (osnoise_data.print_stack)
1407 if (osnoise_data.print_stack <= time_to_us(diff))
1408 timerlat_dump_stack();
1409 #endif /* CONFIG_STACKTRACE */
1411 tlat->tracing_thread = false;
1412 if (osnoise_data.stop_tracing_total)
1413 if (time_to_us(diff) >= osnoise_data.stop_tracing_total)
1414 osnoise_stop_tracing();
1416 wait_next_period(tlat);
1419 hrtimer_cancel(&tlat->timer);
1422 #endif /* CONFIG_TIMERLAT_TRACER */
1425 * stop_kthread - stop a workload thread
1427 static void stop_kthread(unsigned int cpu)
1429 struct task_struct *kthread;
1431 kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
1433 kthread_stop(kthread);
1434 per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
1438 * stop_per_cpu_kthread - Stop per-cpu threads
1440 * Stop the osnoise sampling htread. Use this on unload and at system
1443 static void stop_per_cpu_kthreads(void)
1449 for_each_online_cpu(cpu)
1456 * start_kthread - Start a workload tread
1458 static int start_kthread(unsigned int cpu)
1460 struct task_struct *kthread;
1461 void *main = osnoise_main;
1464 #ifdef CONFIG_TIMERLAT_TRACER
1465 if (osnoise_data.timerlat_tracer) {
1466 snprintf(comm, 24, "timerlat/%d", cpu);
1467 main = timerlat_main;
1469 snprintf(comm, 24, "osnoise/%d", cpu);
1472 snprintf(comm, 24, "osnoise/%d", cpu);
1474 kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
1476 if (IS_ERR(kthread)) {
1477 pr_err(BANNER "could not start sampling thread\n");
1478 stop_per_cpu_kthreads();
1482 per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
1483 wake_up_process(kthread);
1489 * start_per_cpu_kthread - Kick off per-cpu osnoise sampling kthreads
1491 * This starts the kernel thread that will look for osnoise on many
1494 static int start_per_cpu_kthreads(struct trace_array *tr)
1496 struct cpumask *current_mask = &save_cpumask;
1502 * Run only on CPUs in which trace and osnoise are allowed to run.
1504 cpumask_and(current_mask, tr->tracing_cpumask, &osnoise_cpumask);
1506 * And the CPU is online.
1508 cpumask_and(current_mask, cpu_online_mask, current_mask);
1510 for_each_possible_cpu(cpu)
1511 per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
1513 for_each_cpu(cpu, current_mask) {
1514 retval = start_kthread(cpu);
1516 stop_per_cpu_kthreads();
1526 #ifdef CONFIG_HOTPLUG_CPU
1527 static void osnoise_hotplug_workfn(struct work_struct *dummy)
1529 struct trace_array *tr = osnoise_trace;
1530 unsigned int cpu = smp_processor_id();
1533 mutex_lock(&trace_types_lock);
1536 goto out_unlock_trace;
1538 mutex_lock(&interface_lock);
1541 if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
1544 if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
1551 mutex_unlock(&interface_lock);
1553 mutex_unlock(&trace_types_lock);
1556 static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
1559 * osnoise_cpu_init - CPU hotplug online callback function
1561 static int osnoise_cpu_init(unsigned int cpu)
1563 schedule_work_on(cpu, &osnoise_hotplug_work);
1568 * osnoise_cpu_die - CPU hotplug offline callback function
1570 static int osnoise_cpu_die(unsigned int cpu)
1576 static void osnoise_init_hotplug_support(void)
1580 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/osnoise:online",
1581 osnoise_cpu_init, osnoise_cpu_die);
1583 pr_warn(BANNER "Error to init cpu hotplug support\n");
1587 #else /* CONFIG_HOTPLUG_CPU */
1588 static void osnoise_init_hotplug_support(void)
1592 #endif /* CONFIG_HOTPLUG_CPU */
1595 * osnoise_cpus_read - Read function for reading the "cpus" file
1596 * @filp: The active open file structure
1597 * @ubuf: The userspace provided buffer to read value into
1598 * @cnt: The maximum number of bytes to read
1599 * @ppos: The current "file" position
1601 * Prints the "cpus" output into the user-provided buffer.
1604 osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
1610 mutex_lock(&interface_lock);
1612 len = snprintf(NULL, 0, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask)) + 1;
1613 mask_str = kmalloc(len, GFP_KERNEL);
1619 len = snprintf(mask_str, len, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask));
1625 count = simple_read_from_buffer(ubuf, count, ppos, mask_str, len);
1630 mutex_unlock(&interface_lock);
1635 static void osnoise_tracer_start(struct trace_array *tr);
1636 static void osnoise_tracer_stop(struct trace_array *tr);
1639 * osnoise_cpus_write - Write function for "cpus" entry
1640 * @filp: The active open file structure
1641 * @ubuf: The user buffer that contains the value to write
1642 * @cnt: The maximum number of bytes to write to "file"
1643 * @ppos: The current position in @file
1645 * This function provides a write implementation for the "cpus"
1646 * interface to the osnoise trace. By default, it lists all CPUs,
1647 * in this way, allowing osnoise threads to run on any online CPU
1648 * of the system. It serves to restrict the execution of osnoise to the
1649 * set of CPUs writing via this interface. Note that osnoise also
1650 * respects the "tracing_cpumask." Hence, osnoise threads will run only
1651 * on the set of CPUs allowed here AND on "tracing_cpumask." Why not
1652 * have just "tracing_cpumask?" Because the user might be interested
1653 * in tracing what is running on other CPUs. For instance, one might
1654 * run osnoise in one HT CPU while observing what is running on the
1658 osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
1661 struct trace_array *tr = osnoise_trace;
1662 cpumask_var_t osnoise_cpumask_new;
1669 if (copy_from_user(buf, ubuf, count))
1672 if (!zalloc_cpumask_var(&osnoise_cpumask_new, GFP_KERNEL))
1675 err = cpulist_parse(buf, osnoise_cpumask_new);
1680 * trace_types_lock is taken to avoid concurrency on start/stop
1683 mutex_lock(&trace_types_lock);
1684 running = osnoise_busy;
1686 osnoise_tracer_stop(tr);
1688 mutex_lock(&interface_lock);
1690 * osnoise_cpumask is read by CPU hotplug operations.
1694 cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new);
1697 mutex_unlock(&interface_lock);
1700 osnoise_tracer_start(tr);
1701 mutex_unlock(&trace_types_lock);
1703 free_cpumask_var(osnoise_cpumask_new);
1707 free_cpumask_var(osnoise_cpumask_new);
1713 * osnoise/runtime_us: cannot be greater than the period.
1715 static struct trace_min_max_param osnoise_runtime = {
1716 .lock = &interface_lock,
1717 .val = &osnoise_data.sample_runtime,
1718 .max = &osnoise_data.sample_period,
1723 * osnoise/period_us: cannot be smaller than the runtime.
1725 static struct trace_min_max_param osnoise_period = {
1726 .lock = &interface_lock,
1727 .val = &osnoise_data.sample_period,
1729 .min = &osnoise_data.sample_runtime,
1733 * osnoise/stop_tracing_us: no limit.
1735 static struct trace_min_max_param osnoise_stop_tracing_in = {
1736 .lock = &interface_lock,
1737 .val = &osnoise_data.stop_tracing,
1743 * osnoise/stop_tracing_total_us: no limit.
1745 static struct trace_min_max_param osnoise_stop_tracing_total = {
1746 .lock = &interface_lock,
1747 .val = &osnoise_data.stop_tracing_total,
1752 #ifdef CONFIG_TIMERLAT_TRACER
1754 * osnoise/print_stack: print the stacktrace of the IRQ handler if the total
1755 * latency is higher than val.
1757 static struct trace_min_max_param osnoise_print_stack = {
1758 .lock = &interface_lock,
1759 .val = &osnoise_data.print_stack,
1765 * osnoise/timerlat_period: min 100 us, max 1 s
1767 u64 timerlat_min_period = 100;
1768 u64 timerlat_max_period = 1000000;
1769 static struct trace_min_max_param timerlat_period = {
1770 .lock = &interface_lock,
1771 .val = &osnoise_data.timerlat_period,
1772 .max = &timerlat_max_period,
1773 .min = &timerlat_min_period,
1777 static const struct file_operations cpus_fops = {
1778 .open = tracing_open_generic,
1779 .read = osnoise_cpus_read,
1780 .write = osnoise_cpus_write,
1781 .llseek = generic_file_llseek,
1785 * init_tracefs - A function to initialize the tracefs interface files
1787 * This function creates entries in tracefs for "osnoise" and "timerlat".
1788 * It creates these directories in the tracing directory, and within that
1789 * directory the use can change and view the configs.
1791 static int init_tracefs(void)
1793 struct dentry *top_dir;
1797 ret = tracing_init_dentry();
1801 top_dir = tracefs_create_dir("osnoise", NULL);
1805 tmp = tracefs_create_file("period_us", 0640, top_dir,
1806 &osnoise_period, &trace_min_max_fops);
1810 tmp = tracefs_create_file("runtime_us", 0644, top_dir,
1811 &osnoise_runtime, &trace_min_max_fops);
1815 tmp = tracefs_create_file("stop_tracing_us", 0640, top_dir,
1816 &osnoise_stop_tracing_in, &trace_min_max_fops);
1820 tmp = tracefs_create_file("stop_tracing_total_us", 0640, top_dir,
1821 &osnoise_stop_tracing_total, &trace_min_max_fops);
1825 tmp = trace_create_file("cpus", 0644, top_dir, NULL, &cpus_fops);
1828 #ifdef CONFIG_TIMERLAT_TRACER
1829 #ifdef CONFIG_STACKTRACE
1830 tmp = tracefs_create_file("print_stack", 0640, top_dir,
1831 &osnoise_print_stack, &trace_min_max_fops);
1836 tmp = tracefs_create_file("timerlat_period_us", 0640, top_dir,
1837 &timerlat_period, &trace_min_max_fops);
1845 tracefs_remove(top_dir);
1849 static int osnoise_hook_events(void)
1854 * Trace is already hooked, we are re-enabling from
1857 if (trace_osnoise_callback_enabled)
1860 retval = hook_irq_events();
1864 retval = hook_softirq_events();
1866 goto out_unhook_irq;
1868 retval = hook_thread_events();
1875 unhook_softirq_events();
1877 unhook_irq_events();
1881 static int __osnoise_tracer_start(struct trace_array *tr)
1885 osn_var_reset_all();
1887 retval = osnoise_hook_events();
1891 * Make sure NMIs see reseted values.
1894 trace_osnoise_callback_enabled = true;
1896 retval = start_per_cpu_kthreads(tr);
1898 unhook_irq_events();
1902 osnoise_busy = true;
1907 static void osnoise_tracer_start(struct trace_array *tr)
1914 retval = __osnoise_tracer_start(tr);
1916 pr_err(BANNER "Error starting osnoise tracer\n");
1920 static void osnoise_tracer_stop(struct trace_array *tr)
1925 trace_osnoise_callback_enabled = false;
1928 stop_per_cpu_kthreads();
1930 unhook_irq_events();
1931 unhook_softirq_events();
1932 unhook_thread_events();
1934 osnoise_busy = false;
1937 static int osnoise_tracer_init(struct trace_array *tr)
1940 /* Only allow one instance to enable this */
1945 tr->max_latency = 0;
1947 osnoise_tracer_start(tr);
1952 static void osnoise_tracer_reset(struct trace_array *tr)
1954 osnoise_tracer_stop(tr);
1957 static struct tracer osnoise_tracer __read_mostly = {
1959 .init = osnoise_tracer_init,
1960 .reset = osnoise_tracer_reset,
1961 .start = osnoise_tracer_start,
1962 .stop = osnoise_tracer_stop,
1963 .print_header = print_osnoise_headers,
1964 .allow_instances = true,
1967 #ifdef CONFIG_TIMERLAT_TRACER
1968 static void timerlat_tracer_start(struct trace_array *tr)
1975 osnoise_data.timerlat_tracer = 1;
1977 retval = __osnoise_tracer_start(tr);
1983 pr_err(BANNER "Error starting timerlat tracer\n");
1986 static void timerlat_tracer_stop(struct trace_array *tr)
1993 for_each_online_cpu(cpu)
1994 per_cpu(per_cpu_osnoise_var, cpu).sampling = 0;
1996 osnoise_tracer_stop(tr);
1998 osnoise_data.timerlat_tracer = 0;
2001 static int timerlat_tracer_init(struct trace_array *tr)
2003 /* Only allow one instance to enable this */
2009 tr->max_latency = 0;
2011 timerlat_tracer_start(tr);
2016 static void timerlat_tracer_reset(struct trace_array *tr)
2018 timerlat_tracer_stop(tr);
2021 static struct tracer timerlat_tracer __read_mostly = {
2023 .init = timerlat_tracer_init,
2024 .reset = timerlat_tracer_reset,
2025 .start = timerlat_tracer_start,
2026 .stop = timerlat_tracer_stop,
2027 .print_header = print_timerlat_headers,
2028 .allow_instances = true,
2030 #endif /* CONFIG_TIMERLAT_TRACER */
2032 __init static int init_osnoise_tracer(void)
2036 mutex_init(&interface_lock);
2038 cpumask_copy(&osnoise_cpumask, cpu_all_mask);
2040 ret = register_tracer(&osnoise_tracer);
2042 pr_err(BANNER "Error registering osnoise!\n");
2046 #ifdef CONFIG_TIMERLAT_TRACER
2047 ret = register_tracer(&timerlat_tracer);
2049 pr_err(BANNER "Error registering timerlat\n");
2053 osnoise_init_hotplug_support();
2059 late_initcall(init_osnoise_tracer);