mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
2113 lines
51 KiB
2113 lines
51 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* OS Noise Tracer: computes the OS Noise suffered by a running thread. |
|
* Timerlat Tracer: measures the wakeup latency of a timer triggered IRQ and thread. |
|
* |
|
* Based on "hwlat_detector" tracer by: |
|
* Copyright (C) 2008-2009 Jon Masters, Red Hat, Inc. <[email protected]> |
|
* Copyright (C) 2013-2016 Steven Rostedt, Red Hat, Inc. <[email protected]> |
|
* With feedback from Clark Williams <[email protected]> |
|
* |
|
* And also based on the rtsl tracer presented on: |
|
* DE OLIVEIRA, Daniel Bristot, et al. Demystifying the real-time linux |
|
* scheduling latency. In: 32nd Euromicro Conference on Real-Time Systems |
|
* (ECRTS 2020). Schloss Dagstuhl-Leibniz-Zentrum fur Informatik, 2020. |
|
* |
|
* Copyright (C) 2021 Daniel Bristot de Oliveira, Red Hat, Inc. <[email protected]> |
|
*/ |
|
|
|
#include <linux/kthread.h> |
|
#include <linux/tracefs.h> |
|
#include <linux/uaccess.h> |
|
#include <linux/cpumask.h> |
|
#include <linux/delay.h> |
|
#include <linux/sched/clock.h> |
|
#include <uapi/linux/sched/types.h> |
|
#include <linux/sched.h> |
|
#include "trace.h" |
|
|
|
#ifdef CONFIG_X86_LOCAL_APIC |
|
#include <asm/trace/irq_vectors.h> |
|
#undef TRACE_INCLUDE_PATH |
|
#undef TRACE_INCLUDE_FILE |
|
#endif /* CONFIG_X86_LOCAL_APIC */ |
|
|
|
#include <trace/events/irq.h> |
|
#include <trace/events/sched.h> |
|
|
|
#define CREATE_TRACE_POINTS |
|
#include <trace/events/osnoise.h> |
|
|
|
static struct trace_array *osnoise_trace; |
|
|
|
/* |
|
* Default values. |
|
*/ |
|
#define BANNER "osnoise: " |
|
#define DEFAULT_SAMPLE_PERIOD 1000000 /* 1s */ |
|
#define DEFAULT_SAMPLE_RUNTIME 1000000 /* 1s */ |
|
|
|
#define DEFAULT_TIMERLAT_PERIOD 1000 /* 1ms */ |
|
#define DEFAULT_TIMERLAT_PRIO 95 /* FIFO 95 */ |
|
|
|
/* |
|
* NMI runtime info. |
|
*/ |
|
struct osn_nmi { |
|
u64 count; |
|
u64 delta_start; |
|
}; |
|
|
|
/* |
|
* IRQ runtime info. |
|
*/ |
|
struct osn_irq { |
|
u64 count; |
|
u64 arrival_time; |
|
u64 delta_start; |
|
}; |
|
|
|
#define IRQ_CONTEXT 0 |
|
#define THREAD_CONTEXT 1 |
|
/* |
|
* sofirq runtime info. |
|
*/ |
|
struct osn_softirq { |
|
u64 count; |
|
u64 arrival_time; |
|
u64 delta_start; |
|
}; |
|
|
|
/* |
|
* thread runtime info. |
|
*/ |
|
struct osn_thread { |
|
u64 count; |
|
u64 arrival_time; |
|
u64 delta_start; |
|
}; |
|
|
|
/* |
|
* Runtime information: this structure saves the runtime information used by |
|
* one sampling thread. |
|
*/ |
|
struct osnoise_variables { |
|
struct task_struct *kthread; |
|
bool sampling; |
|
pid_t pid; |
|
struct osn_nmi nmi; |
|
struct osn_irq irq; |
|
struct osn_softirq softirq; |
|
struct osn_thread thread; |
|
local_t int_counter; |
|
}; |
|
|
|
/* |
|
* Per-cpu runtime information. |
|
*/ |
|
DEFINE_PER_CPU(struct osnoise_variables, per_cpu_osnoise_var); |
|
|
|
/* |
|
* this_cpu_osn_var - Return the per-cpu osnoise_variables on its relative CPU |
|
*/ |
|
static inline struct osnoise_variables *this_cpu_osn_var(void) |
|
{ |
|
return this_cpu_ptr(&per_cpu_osnoise_var); |
|
} |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* Runtime information for the timer mode. |
|
*/ |
|
struct timerlat_variables { |
|
struct task_struct *kthread; |
|
struct hrtimer timer; |
|
u64 rel_period; |
|
u64 abs_period; |
|
bool tracing_thread; |
|
u64 count; |
|
}; |
|
|
|
DEFINE_PER_CPU(struct timerlat_variables, per_cpu_timerlat_var); |
|
|
|
/* |
|
* this_cpu_tmr_var - Return the per-cpu timerlat_variables on its relative CPU |
|
*/ |
|
static inline struct timerlat_variables *this_cpu_tmr_var(void) |
|
{ |
|
return this_cpu_ptr(&per_cpu_timerlat_var); |
|
} |
|
|
|
/* |
|
* tlat_var_reset - Reset the values of the given timerlat_variables |
|
*/ |
|
static inline void tlat_var_reset(void) |
|
{ |
|
struct timerlat_variables *tlat_var; |
|
int cpu; |
|
/* |
|
* So far, all the values are initialized as 0, so |
|
* zeroing the structure is perfect. |
|
*/ |
|
for_each_cpu(cpu, cpu_online_mask) { |
|
tlat_var = per_cpu_ptr(&per_cpu_timerlat_var, cpu); |
|
memset(tlat_var, 0, sizeof(*tlat_var)); |
|
} |
|
} |
|
#else /* CONFIG_TIMERLAT_TRACER */ |
|
#define tlat_var_reset() do {} while (0) |
|
#endif /* CONFIG_TIMERLAT_TRACER */ |
|
|
|
/* |
|
* osn_var_reset - Reset the values of the given osnoise_variables |
|
*/ |
|
static inline void osn_var_reset(void) |
|
{ |
|
struct osnoise_variables *osn_var; |
|
int cpu; |
|
|
|
/* |
|
* So far, all the values are initialized as 0, so |
|
* zeroing the structure is perfect. |
|
*/ |
|
for_each_cpu(cpu, cpu_online_mask) { |
|
osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu); |
|
memset(osn_var, 0, sizeof(*osn_var)); |
|
} |
|
} |
|
|
|
/* |
|
* osn_var_reset_all - Reset the value of all per-cpu osnoise_variables |
|
*/ |
|
static inline void osn_var_reset_all(void) |
|
{ |
|
osn_var_reset(); |
|
tlat_var_reset(); |
|
} |
|
|
|
/* |
|
* Tells NMIs to call back to the osnoise tracer to record timestamps. |
|
*/ |
|
bool trace_osnoise_callback_enabled; |
|
|
|
/* |
|
* osnoise sample structure definition. Used to store the statistics of a |
|
* sample run. |
|
*/ |
|
struct osnoise_sample { |
|
u64 runtime; /* runtime */ |
|
u64 noise; /* noise */ |
|
u64 max_sample; /* max single noise sample */ |
|
int hw_count; /* # HW (incl. hypervisor) interference */ |
|
int nmi_count; /* # NMIs during this sample */ |
|
int irq_count; /* # IRQs during this sample */ |
|
int softirq_count; /* # softirqs during this sample */ |
|
int thread_count; /* # threads during this sample */ |
|
}; |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* timerlat sample structure definition. Used to store the statistics of |
|
* a sample run. |
|
*/ |
|
struct timerlat_sample { |
|
u64 timer_latency; /* timer_latency */ |
|
unsigned int seqnum; /* unique sequence */ |
|
int context; /* timer context */ |
|
}; |
|
#endif |
|
|
|
/* |
|
* Protect the interface. |
|
*/ |
|
struct mutex interface_lock; |
|
|
|
/* |
|
* Tracer data. |
|
*/ |
|
static struct osnoise_data { |
|
u64 sample_period; /* total sampling period */ |
|
u64 sample_runtime; /* active sampling portion of period */ |
|
u64 stop_tracing; /* stop trace in the internal operation (loop/irq) */ |
|
u64 stop_tracing_total; /* stop trace in the final operation (report/thread) */ |
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
u64 timerlat_period; /* timerlat period */ |
|
u64 print_stack; /* print IRQ stack if total > */ |
|
int timerlat_tracer; /* timerlat tracer */ |
|
#endif |
|
bool tainted; /* infor users and developers about a problem */ |
|
} osnoise_data = { |
|
.sample_period = DEFAULT_SAMPLE_PERIOD, |
|
.sample_runtime = DEFAULT_SAMPLE_RUNTIME, |
|
.stop_tracing = 0, |
|
.stop_tracing_total = 0, |
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
.print_stack = 0, |
|
.timerlat_period = DEFAULT_TIMERLAT_PERIOD, |
|
.timerlat_tracer = 0, |
|
#endif |
|
}; |
|
|
|
/* |
|
* Boolean variable used to inform that the tracer is currently sampling. |
|
*/ |
|
static bool osnoise_busy; |
|
|
|
#ifdef CONFIG_PREEMPT_RT |
|
/* |
|
* Print the osnoise header info. |
|
*/ |
|
static void print_osnoise_headers(struct seq_file *s) |
|
{ |
|
if (osnoise_data.tainted) |
|
seq_puts(s, "# osnoise is tainted!\n"); |
|
|
|
seq_puts(s, "# _-------=> irqs-off\n"); |
|
seq_puts(s, "# / _------=> need-resched\n"); |
|
seq_puts(s, "# | / _-----=> need-resched-lazy\n"); |
|
seq_puts(s, "# || / _----=> hardirq/softirq\n"); |
|
seq_puts(s, "# ||| / _---=> preempt-depth\n"); |
|
seq_puts(s, "# |||| / _--=> preempt-lazy-depth\n"); |
|
seq_puts(s, "# ||||| / _-=> migrate-disable\n"); |
|
|
|
seq_puts(s, "# |||||| / "); |
|
seq_puts(s, " MAX\n"); |
|
|
|
seq_puts(s, "# ||||| / "); |
|
seq_puts(s, " SINGLE Interference counters:\n"); |
|
|
|
seq_puts(s, "# ||||||| RUNTIME "); |
|
seq_puts(s, " NOISE %% OF CPU NOISE +-----------------------------+\n"); |
|
|
|
seq_puts(s, "# TASK-PID CPU# ||||||| TIMESTAMP IN US "); |
|
seq_puts(s, " IN US AVAILABLE IN US HW NMI IRQ SIRQ THREAD\n"); |
|
|
|
seq_puts(s, "# | | | ||||||| | | "); |
|
seq_puts(s, " | | | | | | | |\n"); |
|
} |
|
#else /* CONFIG_PREEMPT_RT */ |
|
static void print_osnoise_headers(struct seq_file *s) |
|
{ |
|
if (osnoise_data.tainted) |
|
seq_puts(s, "# osnoise is tainted!\n"); |
|
|
|
seq_puts(s, "# _-----=> irqs-off\n"); |
|
seq_puts(s, "# / _----=> need-resched\n"); |
|
seq_puts(s, "# | / _---=> hardirq/softirq\n"); |
|
seq_puts(s, "# || / _--=> preempt-depth "); |
|
seq_puts(s, " MAX\n"); |
|
|
|
seq_puts(s, "# || / "); |
|
seq_puts(s, " SINGLE Interference counters:\n"); |
|
|
|
seq_puts(s, "# |||| RUNTIME "); |
|
seq_puts(s, " NOISE %% OF CPU NOISE +-----------------------------+\n"); |
|
|
|
seq_puts(s, "# TASK-PID CPU# |||| TIMESTAMP IN US "); |
|
seq_puts(s, " IN US AVAILABLE IN US HW NMI IRQ SIRQ THREAD\n"); |
|
|
|
seq_puts(s, "# | | | |||| | | "); |
|
seq_puts(s, " | | | | | | | |\n"); |
|
} |
|
#endif /* CONFIG_PREEMPT_RT */ |
|
|
|
/* |
|
* osnoise_taint - report an osnoise error. |
|
*/ |
|
#define osnoise_taint(msg) ({ \ |
|
struct trace_array *tr = osnoise_trace; \ |
|
\ |
|
trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, msg); \ |
|
osnoise_data.tainted = true; \ |
|
}) |
|
|
|
/* |
|
* Record an osnoise_sample into the tracer buffer. |
|
*/ |
|
static void trace_osnoise_sample(struct osnoise_sample *sample) |
|
{ |
|
struct trace_array *tr = osnoise_trace; |
|
struct trace_buffer *buffer = tr->array_buffer.buffer; |
|
struct trace_event_call *call = &event_osnoise; |
|
struct ring_buffer_event *event; |
|
struct osnoise_entry *entry; |
|
|
|
event = trace_buffer_lock_reserve(buffer, TRACE_OSNOISE, sizeof(*entry), |
|
tracing_gen_ctx()); |
|
if (!event) |
|
return; |
|
entry = ring_buffer_event_data(event); |
|
entry->runtime = sample->runtime; |
|
entry->noise = sample->noise; |
|
entry->max_sample = sample->max_sample; |
|
entry->hw_count = sample->hw_count; |
|
entry->nmi_count = sample->nmi_count; |
|
entry->irq_count = sample->irq_count; |
|
entry->softirq_count = sample->softirq_count; |
|
entry->thread_count = sample->thread_count; |
|
|
|
if (!call_filter_check_discard(call, entry, buffer, event)) |
|
trace_buffer_unlock_commit_nostack(buffer, event); |
|
} |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* Print the timerlat header info. |
|
*/ |
|
#ifdef CONFIG_PREEMPT_RT |
|
static void print_timerlat_headers(struct seq_file *s) |
|
{ |
|
seq_puts(s, "# _-------=> irqs-off\n"); |
|
seq_puts(s, "# / _------=> need-resched\n"); |
|
seq_puts(s, "# | / _-----=> need-resched-lazy\n"); |
|
seq_puts(s, "# || / _----=> hardirq/softirq\n"); |
|
seq_puts(s, "# ||| / _---=> preempt-depth\n"); |
|
seq_puts(s, "# |||| / _--=> preempt-lazy-depth\n"); |
|
seq_puts(s, "# ||||| / _-=> migrate-disable\n"); |
|
seq_puts(s, "# |||||| /\n"); |
|
seq_puts(s, "# ||||||| ACTIVATION\n"); |
|
seq_puts(s, "# TASK-PID CPU# ||||||| TIMESTAMP ID "); |
|
seq_puts(s, " CONTEXT LATENCY\n"); |
|
seq_puts(s, "# | | | ||||||| | | "); |
|
seq_puts(s, " | |\n"); |
|
} |
|
#else /* CONFIG_PREEMPT_RT */ |
|
static void print_timerlat_headers(struct seq_file *s) |
|
{ |
|
seq_puts(s, "# _-----=> irqs-off\n"); |
|
seq_puts(s, "# / _----=> need-resched\n"); |
|
seq_puts(s, "# | / _---=> hardirq/softirq\n"); |
|
seq_puts(s, "# || / _--=> preempt-depth\n"); |
|
seq_puts(s, "# || /\n"); |
|
seq_puts(s, "# |||| ACTIVATION\n"); |
|
seq_puts(s, "# TASK-PID CPU# |||| TIMESTAMP ID "); |
|
seq_puts(s, " CONTEXT LATENCY\n"); |
|
seq_puts(s, "# | | | |||| | | "); |
|
seq_puts(s, " | |\n"); |
|
} |
|
#endif /* CONFIG_PREEMPT_RT */ |
|
|
|
/* |
|
* Record an timerlat_sample into the tracer buffer. |
|
*/ |
|
static void trace_timerlat_sample(struct timerlat_sample *sample) |
|
{ |
|
struct trace_array *tr = osnoise_trace; |
|
struct trace_event_call *call = &event_osnoise; |
|
struct trace_buffer *buffer = tr->array_buffer.buffer; |
|
struct ring_buffer_event *event; |
|
struct timerlat_entry *entry; |
|
|
|
event = trace_buffer_lock_reserve(buffer, TRACE_TIMERLAT, sizeof(*entry), |
|
tracing_gen_ctx()); |
|
if (!event) |
|
return; |
|
entry = ring_buffer_event_data(event); |
|
entry->seqnum = sample->seqnum; |
|
entry->context = sample->context; |
|
entry->timer_latency = sample->timer_latency; |
|
|
|
if (!call_filter_check_discard(call, entry, buffer, event)) |
|
trace_buffer_unlock_commit_nostack(buffer, event); |
|
} |
|
|
|
#ifdef CONFIG_STACKTRACE |
|
|
|
#define MAX_CALLS 256 |
|
|
|
/* |
|
* Stack trace will take place only at IRQ level, so, no need |
|
* to control nesting here. |
|
*/ |
|
struct trace_stack { |
|
int stack_size; |
|
int nr_entries; |
|
unsigned long calls[MAX_CALLS]; |
|
}; |
|
|
|
static DEFINE_PER_CPU(struct trace_stack, trace_stack); |
|
|
|
/* |
|
* timerlat_save_stack - save a stack trace without printing |
|
* |
|
* Save the current stack trace without printing. The |
|
* stack will be printed later, after the end of the measurement. |
|
*/ |
|
static void timerlat_save_stack(int skip) |
|
{ |
|
unsigned int size, nr_entries; |
|
struct trace_stack *fstack; |
|
|
|
fstack = this_cpu_ptr(&trace_stack); |
|
|
|
size = ARRAY_SIZE(fstack->calls); |
|
|
|
nr_entries = stack_trace_save(fstack->calls, size, skip); |
|
|
|
fstack->stack_size = nr_entries * sizeof(unsigned long); |
|
fstack->nr_entries = nr_entries; |
|
|
|
return; |
|
|
|
} |
|
/* |
|
* timerlat_dump_stack - dump a stack trace previously saved |
|
* |
|
* Dump a saved stack trace into the trace buffer. |
|
*/ |
|
static void timerlat_dump_stack(void) |
|
{ |
|
struct trace_event_call *call = &event_osnoise; |
|
struct trace_array *tr = osnoise_trace; |
|
struct trace_buffer *buffer = tr->array_buffer.buffer; |
|
struct ring_buffer_event *event; |
|
struct trace_stack *fstack; |
|
struct stack_entry *entry; |
|
unsigned int size; |
|
|
|
preempt_disable_notrace(); |
|
fstack = this_cpu_ptr(&trace_stack); |
|
size = fstack->stack_size; |
|
|
|
event = trace_buffer_lock_reserve(buffer, TRACE_STACK, sizeof(*entry) + size, |
|
tracing_gen_ctx()); |
|
if (!event) |
|
goto out; |
|
|
|
entry = ring_buffer_event_data(event); |
|
|
|
memcpy(&entry->caller, fstack->calls, size); |
|
entry->size = fstack->nr_entries; |
|
|
|
if (!call_filter_check_discard(call, entry, buffer, event)) |
|
trace_buffer_unlock_commit_nostack(buffer, event); |
|
|
|
out: |
|
preempt_enable_notrace(); |
|
} |
|
#else |
|
#define timerlat_dump_stack() do {} while (0) |
|
#define timerlat_save_stack(a) do {} while (0) |
|
#endif /* CONFIG_STACKTRACE */ |
|
#endif /* CONFIG_TIMERLAT_TRACER */ |
|
|
|
/* |
|
* Macros to encapsulate the time capturing infrastructure. |
|
*/ |
|
#define time_get() trace_clock_local() |
|
#define time_to_us(x) div_u64(x, 1000) |
|
#define time_sub(a, b) ((a) - (b)) |
|
|
|
/* |
|
* cond_move_irq_delta_start - Forward the delta_start of a running IRQ |
|
* |
|
* If an IRQ is preempted by an NMI, its delta_start is pushed forward |
|
* to discount the NMI interference. |
|
* |
|
* See get_int_safe_duration(). |
|
*/ |
|
static inline void |
|
cond_move_irq_delta_start(struct osnoise_variables *osn_var, u64 duration) |
|
{ |
|
if (osn_var->irq.delta_start) |
|
osn_var->irq.delta_start += duration; |
|
} |
|
|
|
#ifndef CONFIG_PREEMPT_RT |
|
/* |
|
* cond_move_softirq_delta_start - Forward the delta_start of a running softirq. |
|
* |
|
* If a softirq is preempted by an IRQ or NMI, its delta_start is pushed |
|
* forward to discount the interference. |
|
* |
|
* See get_int_safe_duration(). |
|
*/ |
|
static inline void |
|
cond_move_softirq_delta_start(struct osnoise_variables *osn_var, u64 duration) |
|
{ |
|
if (osn_var->softirq.delta_start) |
|
osn_var->softirq.delta_start += duration; |
|
} |
|
#else /* CONFIG_PREEMPT_RT */ |
|
#define cond_move_softirq_delta_start(osn_var, duration) do {} while (0) |
|
#endif |
|
|
|
/* |
|
* cond_move_thread_delta_start - Forward the delta_start of a running thread |
|
* |
|
* If a noisy thread is preempted by an softirq, IRQ or NMI, its delta_start |
|
* is pushed forward to discount the interference. |
|
* |
|
* See get_int_safe_duration(). |
|
*/ |
|
static inline void |
|
cond_move_thread_delta_start(struct osnoise_variables *osn_var, u64 duration) |
|
{ |
|
if (osn_var->thread.delta_start) |
|
osn_var->thread.delta_start += duration; |
|
} |
|
|
|
/* |
|
* get_int_safe_duration - Get the duration of a window |
|
* |
|
* The irq, softirq and thread varaibles need to have its duration without |
|
* the interference from higher priority interrupts. Instead of keeping a |
|
* variable to discount the interrupt interference from these variables, the |
|
* starting time of these variables are pushed forward with the interrupt's |
|
* duration. In this way, a single variable is used to: |
|
* |
|
* - Know if a given window is being measured. |
|
* - Account its duration. |
|
* - Discount the interference. |
|
* |
|
* To avoid getting inconsistent values, e.g.,: |
|
* |
|
* now = time_get() |
|
* ---> interrupt! |
|
* delta_start -= int duration; |
|
* <--- |
|
* duration = now - delta_start; |
|
* |
|
* result: negative duration if the variable duration before the |
|
* interrupt was smaller than the interrupt execution. |
|
* |
|
* A counter of interrupts is used. If the counter increased, try |
|
* to capture an interference safe duration. |
|
*/ |
|
static inline s64 |
|
get_int_safe_duration(struct osnoise_variables *osn_var, u64 *delta_start) |
|
{ |
|
u64 int_counter, now; |
|
s64 duration; |
|
|
|
do { |
|
int_counter = local_read(&osn_var->int_counter); |
|
/* synchronize with interrupts */ |
|
barrier(); |
|
|
|
now = time_get(); |
|
duration = (now - *delta_start); |
|
|
|
/* synchronize with interrupts */ |
|
barrier(); |
|
} while (int_counter != local_read(&osn_var->int_counter)); |
|
|
|
/* |
|
* This is an evidence of race conditions that cause |
|
* a value to be "discounted" too much. |
|
*/ |
|
if (duration < 0) |
|
osnoise_taint("Negative duration!\n"); |
|
|
|
*delta_start = 0; |
|
|
|
return duration; |
|
} |
|
|
|
/* |
|
* |
|
* set_int_safe_time - Save the current time on *time, aware of interference |
|
* |
|
* Get the time, taking into consideration a possible interference from |
|
* higher priority interrupts. |
|
* |
|
* See get_int_safe_duration() for an explanation. |
|
*/ |
|
static u64 |
|
set_int_safe_time(struct osnoise_variables *osn_var, u64 *time) |
|
{ |
|
u64 int_counter; |
|
|
|
do { |
|
int_counter = local_read(&osn_var->int_counter); |
|
/* synchronize with interrupts */ |
|
barrier(); |
|
|
|
*time = time_get(); |
|
|
|
/* synchronize with interrupts */ |
|
barrier(); |
|
} while (int_counter != local_read(&osn_var->int_counter)); |
|
|
|
return int_counter; |
|
} |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* copy_int_safe_time - Copy *src into *desc aware of interference |
|
*/ |
|
static u64 |
|
copy_int_safe_time(struct osnoise_variables *osn_var, u64 *dst, u64 *src) |
|
{ |
|
u64 int_counter; |
|
|
|
do { |
|
int_counter = local_read(&osn_var->int_counter); |
|
/* synchronize with interrupts */ |
|
barrier(); |
|
|
|
*dst = *src; |
|
|
|
/* synchronize with interrupts */ |
|
barrier(); |
|
} while (int_counter != local_read(&osn_var->int_counter)); |
|
|
|
return int_counter; |
|
} |
|
#endif /* CONFIG_TIMERLAT_TRACER */ |
|
|
|
/* |
|
* trace_osnoise_callback - NMI entry/exit callback |
|
* |
|
* This function is called at the entry and exit NMI code. The bool enter |
|
* distinguishes between either case. This function is used to note a NMI |
|
* occurrence, compute the noise caused by the NMI, and to remove the noise |
|
* it is potentially causing on other interference variables. |
|
*/ |
|
void trace_osnoise_callback(bool enter) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
u64 duration; |
|
|
|
if (!osn_var->sampling) |
|
return; |
|
|
|
/* |
|
* Currently trace_clock_local() calls sched_clock() and the |
|
* generic version is not NMI safe. |
|
*/ |
|
if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) { |
|
if (enter) { |
|
osn_var->nmi.delta_start = time_get(); |
|
local_inc(&osn_var->int_counter); |
|
} else { |
|
duration = time_get() - osn_var->nmi.delta_start; |
|
|
|
trace_nmi_noise(osn_var->nmi.delta_start, duration); |
|
|
|
cond_move_irq_delta_start(osn_var, duration); |
|
cond_move_softirq_delta_start(osn_var, duration); |
|
cond_move_thread_delta_start(osn_var, duration); |
|
} |
|
} |
|
|
|
if (enter) |
|
osn_var->nmi.count++; |
|
} |
|
|
|
/* |
|
* osnoise_trace_irq_entry - Note the starting of an IRQ |
|
* |
|
* Save the starting time of an IRQ. As IRQs are non-preemptive to other IRQs, |
|
* it is safe to use a single variable (ons_var->irq) to save the statistics. |
|
* The arrival_time is used to report... the arrival time. The delta_start |
|
* is used to compute the duration at the IRQ exit handler. See |
|
* cond_move_irq_delta_start(). |
|
*/ |
|
void osnoise_trace_irq_entry(int id) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
|
|
if (!osn_var->sampling) |
|
return; |
|
/* |
|
* This value will be used in the report, but not to compute |
|
* the execution time, so it is safe to get it unsafe. |
|
*/ |
|
osn_var->irq.arrival_time = time_get(); |
|
set_int_safe_time(osn_var, &osn_var->irq.delta_start); |
|
osn_var->irq.count++; |
|
|
|
local_inc(&osn_var->int_counter); |
|
} |
|
|
|
/* |
|
* osnoise_irq_exit - Note the end of an IRQ, sava data and trace |
|
* |
|
* Computes the duration of the IRQ noise, and trace it. Also discounts the |
|
* interference from other sources of noise could be currently being accounted. |
|
*/ |
|
void osnoise_trace_irq_exit(int id, const char *desc) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
int duration; |
|
|
|
if (!osn_var->sampling) |
|
return; |
|
|
|
duration = get_int_safe_duration(osn_var, &osn_var->irq.delta_start); |
|
trace_irq_noise(id, desc, osn_var->irq.arrival_time, duration); |
|
osn_var->irq.arrival_time = 0; |
|
cond_move_softirq_delta_start(osn_var, duration); |
|
cond_move_thread_delta_start(osn_var, duration); |
|
} |
|
|
|
/* |
|
* trace_irqentry_callback - Callback to the irq:irq_entry traceevent |
|
* |
|
* Used to note the starting of an IRQ occurece. |
|
*/ |
|
static void trace_irqentry_callback(void *data, int irq, |
|
struct irqaction *action) |
|
{ |
|
osnoise_trace_irq_entry(irq); |
|
} |
|
|
|
/* |
|
* trace_irqexit_callback - Callback to the irq:irq_exit traceevent |
|
* |
|
* Used to note the end of an IRQ occurece. |
|
*/ |
|
static void trace_irqexit_callback(void *data, int irq, |
|
struct irqaction *action, int ret) |
|
{ |
|
osnoise_trace_irq_exit(irq, action->name); |
|
} |
|
|
|
/* |
|
* arch specific register function. |
|
*/ |
|
int __weak osnoise_arch_register(void) |
|
{ |
|
return 0; |
|
} |
|
|
|
/* |
|
* arch specific unregister function. |
|
*/ |
|
void __weak osnoise_arch_unregister(void) |
|
{ |
|
return; |
|
} |
|
|
|
/* |
|
* hook_irq_events - Hook IRQ handling events |
|
* |
|
* This function hooks the IRQ related callbacks to the respective trace |
|
* events. |
|
*/ |
|
static int hook_irq_events(void) |
|
{ |
|
int ret; |
|
|
|
ret = register_trace_irq_handler_entry(trace_irqentry_callback, NULL); |
|
if (ret) |
|
goto out_err; |
|
|
|
ret = register_trace_irq_handler_exit(trace_irqexit_callback, NULL); |
|
if (ret) |
|
goto out_unregister_entry; |
|
|
|
ret = osnoise_arch_register(); |
|
if (ret) |
|
goto out_irq_exit; |
|
|
|
return 0; |
|
|
|
out_irq_exit: |
|
unregister_trace_irq_handler_exit(trace_irqexit_callback, NULL); |
|
out_unregister_entry: |
|
unregister_trace_irq_handler_entry(trace_irqentry_callback, NULL); |
|
out_err: |
|
return -EINVAL; |
|
} |
|
|
|
/* |
|
* unhook_irq_events - Unhook IRQ handling events |
|
* |
|
* This function unhooks the IRQ related callbacks to the respective trace |
|
* events. |
|
*/ |
|
static void unhook_irq_events(void) |
|
{ |
|
osnoise_arch_unregister(); |
|
unregister_trace_irq_handler_exit(trace_irqexit_callback, NULL); |
|
unregister_trace_irq_handler_entry(trace_irqentry_callback, NULL); |
|
} |
|
|
|
#ifndef CONFIG_PREEMPT_RT |
|
/* |
|
* trace_softirq_entry_callback - Note the starting of a softirq |
|
* |
|
* Save the starting time of a softirq. As softirqs are non-preemptive to |
|
* other softirqs, it is safe to use a single variable (ons_var->softirq) |
|
* to save the statistics. The arrival_time is used to report... the |
|
* arrival time. The delta_start is used to compute the duration at the |
|
* softirq exit handler. See cond_move_softirq_delta_start(). |
|
*/ |
|
static void trace_softirq_entry_callback(void *data, unsigned int vec_nr) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
|
|
if (!osn_var->sampling) |
|
return; |
|
/* |
|
* This value will be used in the report, but not to compute |
|
* the execution time, so it is safe to get it unsafe. |
|
*/ |
|
osn_var->softirq.arrival_time = time_get(); |
|
set_int_safe_time(osn_var, &osn_var->softirq.delta_start); |
|
osn_var->softirq.count++; |
|
|
|
local_inc(&osn_var->int_counter); |
|
} |
|
|
|
/* |
|
* trace_softirq_exit_callback - Note the end of an softirq |
|
* |
|
* Computes the duration of the softirq noise, and trace it. Also discounts the |
|
* interference from other sources of noise could be currently being accounted. |
|
*/ |
|
static void trace_softirq_exit_callback(void *data, unsigned int vec_nr) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
int duration; |
|
|
|
if (!osn_var->sampling) |
|
return; |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* If the timerlat is enabled, but the irq handler did |
|
* not run yet enabling timerlat_tracer, do not trace. |
|
*/ |
|
if (unlikely(osnoise_data.timerlat_tracer)) { |
|
struct timerlat_variables *tlat_var; |
|
tlat_var = this_cpu_tmr_var(); |
|
if (!tlat_var->tracing_thread) { |
|
osn_var->softirq.arrival_time = 0; |
|
osn_var->softirq.delta_start = 0; |
|
return; |
|
} |
|
} |
|
#endif |
|
|
|
duration = get_int_safe_duration(osn_var, &osn_var->softirq.delta_start); |
|
trace_softirq_noise(vec_nr, osn_var->softirq.arrival_time, duration); |
|
cond_move_thread_delta_start(osn_var, duration); |
|
osn_var->softirq.arrival_time = 0; |
|
} |
|
|
|
/* |
|
* hook_softirq_events - Hook softirq handling events |
|
* |
|
* This function hooks the softirq related callbacks to the respective trace |
|
* events. |
|
*/ |
|
static int hook_softirq_events(void) |
|
{ |
|
int ret; |
|
|
|
ret = register_trace_softirq_entry(trace_softirq_entry_callback, NULL); |
|
if (ret) |
|
goto out_err; |
|
|
|
ret = register_trace_softirq_exit(trace_softirq_exit_callback, NULL); |
|
if (ret) |
|
goto out_unreg_entry; |
|
|
|
return 0; |
|
|
|
out_unreg_entry: |
|
unregister_trace_softirq_entry(trace_softirq_entry_callback, NULL); |
|
out_err: |
|
return -EINVAL; |
|
} |
|
|
|
/* |
|
* unhook_softirq_events - Unhook softirq handling events |
|
* |
|
* This function hooks the softirq related callbacks to the respective trace |
|
* events. |
|
*/ |
|
static void unhook_softirq_events(void) |
|
{ |
|
unregister_trace_softirq_entry(trace_softirq_entry_callback, NULL); |
|
unregister_trace_softirq_exit(trace_softirq_exit_callback, NULL); |
|
} |
|
#else /* CONFIG_PREEMPT_RT */ |
|
/* |
|
* softirq are threads on the PREEMPT_RT mode. |
|
*/ |
|
static int hook_softirq_events(void) |
|
{ |
|
return 0; |
|
} |
|
static void unhook_softirq_events(void) |
|
{ |
|
} |
|
#endif |
|
|
|
/* |
|
* thread_entry - Record the starting of a thread noise window |
|
* |
|
* It saves the context switch time for a noisy thread, and increments |
|
* the interference counters. |
|
*/ |
|
static void |
|
thread_entry(struct osnoise_variables *osn_var, struct task_struct *t) |
|
{ |
|
if (!osn_var->sampling) |
|
return; |
|
/* |
|
* The arrival time will be used in the report, but not to compute |
|
* the execution time, so it is safe to get it unsafe. |
|
*/ |
|
osn_var->thread.arrival_time = time_get(); |
|
|
|
set_int_safe_time(osn_var, &osn_var->thread.delta_start); |
|
|
|
osn_var->thread.count++; |
|
local_inc(&osn_var->int_counter); |
|
} |
|
|
|
/* |
|
* thread_exit - Report the end of a thread noise window |
|
* |
|
* It computes the total noise from a thread, tracing if needed. |
|
*/ |
|
static void |
|
thread_exit(struct osnoise_variables *osn_var, struct task_struct *t) |
|
{ |
|
int duration; |
|
|
|
if (!osn_var->sampling) |
|
return; |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
if (osnoise_data.timerlat_tracer) { |
|
struct timerlat_variables *tlat_var; |
|
tlat_var = this_cpu_tmr_var(); |
|
if (!tlat_var->tracing_thread) { |
|
osn_var->thread.delta_start = 0; |
|
osn_var->thread.arrival_time = 0; |
|
return; |
|
} |
|
} |
|
#endif |
|
|
|
duration = get_int_safe_duration(osn_var, &osn_var->thread.delta_start); |
|
|
|
trace_thread_noise(t, osn_var->thread.arrival_time, duration); |
|
|
|
osn_var->thread.arrival_time = 0; |
|
} |
|
|
|
/* |
|
* trace_sched_switch - sched:sched_switch trace event handler |
|
* |
|
* This function is hooked to the sched:sched_switch trace event, and it is |
|
* used to record the beginning and to report the end of a thread noise window. |
|
*/ |
|
static void |
|
trace_sched_switch_callback(void *data, bool preempt, struct task_struct *p, |
|
struct task_struct *n) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
|
|
if (p->pid != osn_var->pid) |
|
thread_exit(osn_var, p); |
|
|
|
if (n->pid != osn_var->pid) |
|
thread_entry(osn_var, n); |
|
} |
|
|
|
/* |
|
* hook_thread_events - Hook the insturmentation for thread noise |
|
* |
|
* Hook the osnoise tracer callbacks to handle the noise from other |
|
* threads on the necessary kernel events. |
|
*/ |
|
static int hook_thread_events(void) |
|
{ |
|
int ret; |
|
|
|
ret = register_trace_sched_switch(trace_sched_switch_callback, NULL); |
|
if (ret) |
|
return -EINVAL; |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* unhook_thread_events - *nhook the insturmentation for thread noise |
|
* |
|
* Unook the osnoise tracer callbacks to handle the noise from other |
|
* threads on the necessary kernel events. |
|
*/ |
|
static void unhook_thread_events(void) |
|
{ |
|
unregister_trace_sched_switch(trace_sched_switch_callback, NULL); |
|
} |
|
|
|
/* |
|
* save_osn_sample_stats - Save the osnoise_sample statistics |
|
* |
|
* Save the osnoise_sample statistics before the sampling phase. These |
|
* values will be used later to compute the diff betwneen the statistics |
|
* before and after the osnoise sampling. |
|
*/ |
|
static void |
|
save_osn_sample_stats(struct osnoise_variables *osn_var, struct osnoise_sample *s) |
|
{ |
|
s->nmi_count = osn_var->nmi.count; |
|
s->irq_count = osn_var->irq.count; |
|
s->softirq_count = osn_var->softirq.count; |
|
s->thread_count = osn_var->thread.count; |
|
} |
|
|
|
/* |
|
* diff_osn_sample_stats - Compute the osnoise_sample statistics |
|
* |
|
* After a sample period, compute the difference on the osnoise_sample |
|
* statistics. The struct osnoise_sample *s contains the statistics saved via |
|
* save_osn_sample_stats() before the osnoise sampling. |
|
*/ |
|
static void |
|
diff_osn_sample_stats(struct osnoise_variables *osn_var, struct osnoise_sample *s) |
|
{ |
|
s->nmi_count = osn_var->nmi.count - s->nmi_count; |
|
s->irq_count = osn_var->irq.count - s->irq_count; |
|
s->softirq_count = osn_var->softirq.count - s->softirq_count; |
|
s->thread_count = osn_var->thread.count - s->thread_count; |
|
} |
|
|
|
/* |
|
* osnoise_stop_tracing - Stop tracing and the tracer. |
|
*/ |
|
static __always_inline void osnoise_stop_tracing(void) |
|
{ |
|
struct trace_array *tr = osnoise_trace; |
|
|
|
trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, |
|
"stop tracing hit on cpu %d\n", smp_processor_id()); |
|
|
|
tracer_tracing_off(tr); |
|
} |
|
|
|
/* |
|
* run_osnoise - Sample the time and look for osnoise |
|
* |
|
* Used to capture the time, looking for potential osnoise latency repeatedly. |
|
* Different from hwlat_detector, it is called with preemption and interrupts |
|
* enabled. This allows irqs, softirqs and threads to run, interfering on the |
|
* osnoise sampling thread, as they would do with a regular thread. |
|
*/ |
|
static int run_osnoise(void) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
struct trace_array *tr = osnoise_trace; |
|
u64 start, sample, last_sample; |
|
u64 last_int_count, int_count; |
|
s64 noise = 0, max_noise = 0; |
|
s64 total, last_total = 0; |
|
struct osnoise_sample s; |
|
unsigned int threshold; |
|
u64 runtime, stop_in; |
|
u64 sum_noise = 0; |
|
int hw_count = 0; |
|
int ret = -1; |
|
|
|
/* |
|
* Considers the current thread as the workload. |
|
*/ |
|
osn_var->pid = current->pid; |
|
|
|
/* |
|
* Save the current stats for the diff |
|
*/ |
|
save_osn_sample_stats(osn_var, &s); |
|
|
|
/* |
|
* if threshold is 0, use the default value of 5 us. |
|
*/ |
|
threshold = tracing_thresh ? : 5000; |
|
|
|
/* |
|
* Make sure NMIs see sampling first |
|
*/ |
|
osn_var->sampling = true; |
|
barrier(); |
|
|
|
/* |
|
* Transform the *_us config to nanoseconds to avoid the |
|
* division on the main loop. |
|
*/ |
|
runtime = osnoise_data.sample_runtime * NSEC_PER_USEC; |
|
stop_in = osnoise_data.stop_tracing * NSEC_PER_USEC; |
|
|
|
/* |
|
* Start timestemp |
|
*/ |
|
start = time_get(); |
|
|
|
/* |
|
* "previous" loop. |
|
*/ |
|
last_int_count = set_int_safe_time(osn_var, &last_sample); |
|
|
|
do { |
|
/* |
|
* Get sample! |
|
*/ |
|
int_count = set_int_safe_time(osn_var, &sample); |
|
|
|
noise = time_sub(sample, last_sample); |
|
|
|
/* |
|
* This shouldn't happen. |
|
*/ |
|
if (noise < 0) { |
|
osnoise_taint("negative noise!"); |
|
goto out; |
|
} |
|
|
|
/* |
|
* Sample runtime. |
|
*/ |
|
total = time_sub(sample, start); |
|
|
|
/* |
|
* Check for possible overflows. |
|
*/ |
|
if (total < last_total) { |
|
osnoise_taint("total overflow!"); |
|
break; |
|
} |
|
|
|
last_total = total; |
|
|
|
if (noise >= threshold) { |
|
int interference = int_count - last_int_count; |
|
|
|
if (noise > max_noise) |
|
max_noise = noise; |
|
|
|
if (!interference) |
|
hw_count++; |
|
|
|
sum_noise += noise; |
|
|
|
trace_sample_threshold(last_sample, noise, interference); |
|
|
|
if (osnoise_data.stop_tracing) |
|
if (noise > stop_in) |
|
osnoise_stop_tracing(); |
|
} |
|
|
|
/* |
|
* For the non-preemptive kernel config: let threads runs, if |
|
* they so wish. |
|
*/ |
|
cond_resched(); |
|
|
|
last_sample = sample; |
|
last_int_count = int_count; |
|
|
|
} while (total < runtime && !kthread_should_stop()); |
|
|
|
/* |
|
* Finish the above in the view for interrupts. |
|
*/ |
|
barrier(); |
|
|
|
osn_var->sampling = false; |
|
|
|
/* |
|
* Make sure sampling data is no longer updated. |
|
*/ |
|
barrier(); |
|
|
|
/* |
|
* Save noise info. |
|
*/ |
|
s.noise = time_to_us(sum_noise); |
|
s.runtime = time_to_us(total); |
|
s.max_sample = time_to_us(max_noise); |
|
s.hw_count = hw_count; |
|
|
|
/* Save interference stats info */ |
|
diff_osn_sample_stats(osn_var, &s); |
|
|
|
trace_osnoise_sample(&s); |
|
|
|
/* Keep a running maximum ever recorded osnoise "latency" */ |
|
if (max_noise > tr->max_latency) { |
|
tr->max_latency = max_noise; |
|
latency_fsnotify(tr); |
|
} |
|
|
|
if (osnoise_data.stop_tracing_total) |
|
if (s.noise > osnoise_data.stop_tracing_total) |
|
osnoise_stop_tracing(); |
|
|
|
return 0; |
|
out: |
|
return ret; |
|
} |
|
|
|
static struct cpumask osnoise_cpumask; |
|
static struct cpumask save_cpumask; |
|
|
|
/* |
|
* osnoise_main - The osnoise detection kernel thread |
|
* |
|
* Calls run_osnoise() function to measure the osnoise for the configured runtime, |
|
* every period. |
|
*/ |
|
static int osnoise_main(void *data) |
|
{ |
|
u64 interval; |
|
|
|
while (!kthread_should_stop()) { |
|
|
|
run_osnoise(); |
|
|
|
mutex_lock(&interface_lock); |
|
interval = osnoise_data.sample_period - osnoise_data.sample_runtime; |
|
mutex_unlock(&interface_lock); |
|
|
|
do_div(interval, USEC_PER_MSEC); |
|
|
|
/* |
|
* differently from hwlat_detector, the osnoise tracer can run |
|
* without a pause because preemption is on. |
|
*/ |
|
if (interval < 1) { |
|
/* Let synchronize_rcu_tasks() make progress */ |
|
cond_resched_tasks_rcu_qs(); |
|
continue; |
|
} |
|
|
|
if (msleep_interruptible(interval)) |
|
break; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* timerlat_irq - hrtimer handler for timerlat. |
|
*/ |
|
static enum hrtimer_restart timerlat_irq(struct hrtimer *timer) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
struct trace_array *tr = osnoise_trace; |
|
struct timerlat_variables *tlat; |
|
struct timerlat_sample s; |
|
u64 now; |
|
u64 diff; |
|
|
|
/* |
|
* I am not sure if the timer was armed for this CPU. So, get |
|
* the timerlat struct from the timer itself, not from this |
|
* CPU. |
|
*/ |
|
tlat = container_of(timer, struct timerlat_variables, timer); |
|
|
|
now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer)); |
|
|
|
/* |
|
* Enable the osnoise: events for thread an softirq. |
|
*/ |
|
tlat->tracing_thread = true; |
|
|
|
osn_var->thread.arrival_time = time_get(); |
|
|
|
/* |
|
* A hardirq is running: the timer IRQ. It is for sure preempting |
|
* a thread, and potentially preempting a softirq. |
|
* |
|
* At this point, it is not interesting to know the duration of the |
|
* preempted thread (and maybe softirq), but how much time they will |
|
* delay the beginning of the execution of the timer thread. |
|
* |
|
* To get the correct (net) delay added by the softirq, its delta_start |
|
* is set as the IRQ one. In this way, at the return of the IRQ, the delta |
|
* start of the sofitrq will be zeroed, accounting then only the time |
|
* after that. |
|
* |
|
* The thread follows the same principle. However, if a softirq is |
|
* running, the thread needs to receive the softirq delta_start. The |
|
* reason being is that the softirq will be the last to be unfolded, |
|
* resseting the thread delay to zero. |
|
*/ |
|
#ifndef CONFIG_PREEMPT_RT |
|
if (osn_var->softirq.delta_start) { |
|
copy_int_safe_time(osn_var, &osn_var->thread.delta_start, |
|
&osn_var->softirq.delta_start); |
|
|
|
copy_int_safe_time(osn_var, &osn_var->softirq.delta_start, |
|
&osn_var->irq.delta_start); |
|
} else { |
|
copy_int_safe_time(osn_var, &osn_var->thread.delta_start, |
|
&osn_var->irq.delta_start); |
|
} |
|
#else /* CONFIG_PREEMPT_RT */ |
|
/* |
|
* The sofirqs run as threads on RT, so there is not need |
|
* to keep track of it. |
|
*/ |
|
copy_int_safe_time(osn_var, &osn_var->thread.delta_start, &osn_var->irq.delta_start); |
|
#endif /* CONFIG_PREEMPT_RT */ |
|
|
|
/* |
|
* Compute the current time with the expected time. |
|
*/ |
|
diff = now - tlat->abs_period; |
|
|
|
tlat->count++; |
|
s.seqnum = tlat->count; |
|
s.timer_latency = diff; |
|
s.context = IRQ_CONTEXT; |
|
|
|
trace_timerlat_sample(&s); |
|
|
|
/* Keep a running maximum ever recorded os noise "latency" */ |
|
if (diff > tr->max_latency) { |
|
tr->max_latency = diff; |
|
latency_fsnotify(tr); |
|
} |
|
|
|
if (osnoise_data.stop_tracing) |
|
if (time_to_us(diff) >= osnoise_data.stop_tracing) |
|
osnoise_stop_tracing(); |
|
|
|
wake_up_process(tlat->kthread); |
|
|
|
if (osnoise_data.print_stack) |
|
timerlat_save_stack(0); |
|
|
|
return HRTIMER_NORESTART; |
|
} |
|
|
|
/* |
|
* wait_next_period - Wait for the next period for timerlat |
|
*/ |
|
static int wait_next_period(struct timerlat_variables *tlat) |
|
{ |
|
ktime_t next_abs_period, now; |
|
u64 rel_period = osnoise_data.timerlat_period * 1000; |
|
|
|
now = hrtimer_cb_get_time(&tlat->timer); |
|
next_abs_period = ns_to_ktime(tlat->abs_period + rel_period); |
|
|
|
/* |
|
* Save the next abs_period. |
|
*/ |
|
tlat->abs_period = (u64) ktime_to_ns(next_abs_period); |
|
|
|
/* |
|
* If the new abs_period is in the past, skip the activation. |
|
*/ |
|
while (ktime_compare(now, next_abs_period) > 0) { |
|
next_abs_period = ns_to_ktime(tlat->abs_period + rel_period); |
|
tlat->abs_period = (u64) ktime_to_ns(next_abs_period); |
|
} |
|
|
|
set_current_state(TASK_INTERRUPTIBLE); |
|
|
|
hrtimer_start(&tlat->timer, next_abs_period, HRTIMER_MODE_ABS_PINNED_HARD); |
|
schedule(); |
|
return 1; |
|
} |
|
|
|
/* |
|
* timerlat_main- Timerlat main |
|
*/ |
|
static int timerlat_main(void *data) |
|
{ |
|
struct osnoise_variables *osn_var = this_cpu_osn_var(); |
|
struct timerlat_variables *tlat = this_cpu_tmr_var(); |
|
struct timerlat_sample s; |
|
struct sched_param sp; |
|
u64 now, diff; |
|
|
|
/* |
|
* Make the thread RT, that is how cyclictest is usually used. |
|
*/ |
|
sp.sched_priority = DEFAULT_TIMERLAT_PRIO; |
|
sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); |
|
|
|
tlat->count = 0; |
|
tlat->tracing_thread = false; |
|
|
|
hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD); |
|
tlat->timer.function = timerlat_irq; |
|
tlat->kthread = current; |
|
osn_var->pid = current->pid; |
|
/* |
|
* Anotate the arrival time. |
|
*/ |
|
tlat->abs_period = hrtimer_cb_get_time(&tlat->timer); |
|
|
|
wait_next_period(tlat); |
|
|
|
osn_var->sampling = 1; |
|
|
|
while (!kthread_should_stop()) { |
|
now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer)); |
|
diff = now - tlat->abs_period; |
|
|
|
s.seqnum = tlat->count; |
|
s.timer_latency = diff; |
|
s.context = THREAD_CONTEXT; |
|
|
|
trace_timerlat_sample(&s); |
|
|
|
#ifdef CONFIG_STACKTRACE |
|
if (osnoise_data.print_stack) |
|
if (osnoise_data.print_stack <= time_to_us(diff)) |
|
timerlat_dump_stack(); |
|
#endif /* CONFIG_STACKTRACE */ |
|
|
|
tlat->tracing_thread = false; |
|
if (osnoise_data.stop_tracing_total) |
|
if (time_to_us(diff) >= osnoise_data.stop_tracing_total) |
|
osnoise_stop_tracing(); |
|
|
|
wait_next_period(tlat); |
|
} |
|
|
|
hrtimer_cancel(&tlat->timer); |
|
return 0; |
|
} |
|
#endif /* CONFIG_TIMERLAT_TRACER */ |
|
|
|
/* |
|
* stop_kthread - stop a workload thread |
|
*/ |
|
static void stop_kthread(unsigned int cpu) |
|
{ |
|
struct task_struct *kthread; |
|
|
|
kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread; |
|
if (kthread) |
|
kthread_stop(kthread); |
|
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL; |
|
} |
|
|
|
/* |
|
* stop_per_cpu_kthread - Stop per-cpu threads |
|
* |
|
* Stop the osnoise sampling htread. Use this on unload and at system |
|
* shutdown. |
|
*/ |
|
static void stop_per_cpu_kthreads(void) |
|
{ |
|
int cpu; |
|
|
|
cpus_read_lock(); |
|
|
|
for_each_online_cpu(cpu) |
|
stop_kthread(cpu); |
|
|
|
cpus_read_unlock(); |
|
} |
|
|
|
/* |
|
* start_kthread - Start a workload tread |
|
*/ |
|
static int start_kthread(unsigned int cpu) |
|
{ |
|
struct task_struct *kthread; |
|
void *main = osnoise_main; |
|
char comm[24]; |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
if (osnoise_data.timerlat_tracer) { |
|
snprintf(comm, 24, "timerlat/%d", cpu); |
|
main = timerlat_main; |
|
} else { |
|
snprintf(comm, 24, "osnoise/%d", cpu); |
|
} |
|
#else |
|
snprintf(comm, 24, "osnoise/%d", cpu); |
|
#endif |
|
kthread = kthread_create_on_cpu(main, NULL, cpu, comm); |
|
|
|
if (IS_ERR(kthread)) { |
|
pr_err(BANNER "could not start sampling thread\n"); |
|
stop_per_cpu_kthreads(); |
|
return -ENOMEM; |
|
} |
|
|
|
per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread; |
|
wake_up_process(kthread); |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* start_per_cpu_kthread - Kick off per-cpu osnoise sampling kthreads |
|
* |
|
* This starts the kernel thread that will look for osnoise on many |
|
* cpus. |
|
*/ |
|
static int start_per_cpu_kthreads(struct trace_array *tr) |
|
{ |
|
struct cpumask *current_mask = &save_cpumask; |
|
int retval = 0; |
|
int cpu; |
|
|
|
cpus_read_lock(); |
|
/* |
|
* Run only on CPUs in which trace and osnoise are allowed to run. |
|
*/ |
|
cpumask_and(current_mask, tr->tracing_cpumask, &osnoise_cpumask); |
|
/* |
|
* And the CPU is online. |
|
*/ |
|
cpumask_and(current_mask, cpu_online_mask, current_mask); |
|
|
|
for_each_possible_cpu(cpu) |
|
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL; |
|
|
|
for_each_cpu(cpu, current_mask) { |
|
retval = start_kthread(cpu); |
|
if (retval) { |
|
stop_per_cpu_kthreads(); |
|
break; |
|
} |
|
} |
|
|
|
cpus_read_unlock(); |
|
|
|
return retval; |
|
} |
|
|
|
#ifdef CONFIG_HOTPLUG_CPU |
|
static void osnoise_hotplug_workfn(struct work_struct *dummy) |
|
{ |
|
struct trace_array *tr = osnoise_trace; |
|
unsigned int cpu = smp_processor_id(); |
|
|
|
|
|
mutex_lock(&trace_types_lock); |
|
|
|
if (!osnoise_busy) |
|
goto out_unlock_trace; |
|
|
|
mutex_lock(&interface_lock); |
|
cpus_read_lock(); |
|
|
|
if (!cpumask_test_cpu(cpu, &osnoise_cpumask)) |
|
goto out_unlock; |
|
|
|
if (!cpumask_test_cpu(cpu, tr->tracing_cpumask)) |
|
goto out_unlock; |
|
|
|
start_kthread(cpu); |
|
|
|
out_unlock: |
|
cpus_read_unlock(); |
|
mutex_unlock(&interface_lock); |
|
out_unlock_trace: |
|
mutex_unlock(&trace_types_lock); |
|
} |
|
|
|
static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn); |
|
|
|
/* |
|
* osnoise_cpu_init - CPU hotplug online callback function |
|
*/ |
|
static int osnoise_cpu_init(unsigned int cpu) |
|
{ |
|
schedule_work_on(cpu, &osnoise_hotplug_work); |
|
return 0; |
|
} |
|
|
|
/* |
|
* osnoise_cpu_die - CPU hotplug offline callback function |
|
*/ |
|
static int osnoise_cpu_die(unsigned int cpu) |
|
{ |
|
stop_kthread(cpu); |
|
return 0; |
|
} |
|
|
|
static void osnoise_init_hotplug_support(void) |
|
{ |
|
int ret; |
|
|
|
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/osnoise:online", |
|
osnoise_cpu_init, osnoise_cpu_die); |
|
if (ret < 0) |
|
pr_warn(BANNER "Error to init cpu hotplug support\n"); |
|
|
|
return; |
|
} |
|
#else /* CONFIG_HOTPLUG_CPU */ |
|
static void osnoise_init_hotplug_support(void) |
|
{ |
|
return; |
|
} |
|
#endif /* CONFIG_HOTPLUG_CPU */ |
|
|
|
/* |
|
* osnoise_cpus_read - Read function for reading the "cpus" file |
|
* @filp: The active open file structure |
|
* @ubuf: The userspace provided buffer to read value into |
|
* @cnt: The maximum number of bytes to read |
|
* @ppos: The current "file" position |
|
* |
|
* Prints the "cpus" output into the user-provided buffer. |
|
*/ |
|
static ssize_t |
|
osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count, |
|
loff_t *ppos) |
|
{ |
|
char *mask_str; |
|
int len; |
|
|
|
mutex_lock(&interface_lock); |
|
|
|
len = snprintf(NULL, 0, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask)) + 1; |
|
mask_str = kmalloc(len, GFP_KERNEL); |
|
if (!mask_str) { |
|
count = -ENOMEM; |
|
goto out_unlock; |
|
} |
|
|
|
len = snprintf(mask_str, len, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask)); |
|
if (len >= count) { |
|
count = -EINVAL; |
|
goto out_free; |
|
} |
|
|
|
count = simple_read_from_buffer(ubuf, count, ppos, mask_str, len); |
|
|
|
out_free: |
|
kfree(mask_str); |
|
out_unlock: |
|
mutex_unlock(&interface_lock); |
|
|
|
return count; |
|
} |
|
|
|
static void osnoise_tracer_start(struct trace_array *tr); |
|
static void osnoise_tracer_stop(struct trace_array *tr); |
|
|
|
/* |
|
* osnoise_cpus_write - Write function for "cpus" entry |
|
* @filp: The active open file structure |
|
* @ubuf: The user buffer that contains the value to write |
|
* @cnt: The maximum number of bytes to write to "file" |
|
* @ppos: The current position in @file |
|
* |
|
* This function provides a write implementation for the "cpus" |
|
* interface to the osnoise trace. By default, it lists all CPUs, |
|
* in this way, allowing osnoise threads to run on any online CPU |
|
* of the system. It serves to restrict the execution of osnoise to the |
|
* set of CPUs writing via this interface. Note that osnoise also |
|
* respects the "tracing_cpumask." Hence, osnoise threads will run only |
|
* on the set of CPUs allowed here AND on "tracing_cpumask." Why not |
|
* have just "tracing_cpumask?" Because the user might be interested |
|
* in tracing what is running on other CPUs. For instance, one might |
|
* run osnoise in one HT CPU while observing what is running on the |
|
* sibling HT CPU. |
|
*/ |
|
static ssize_t |
|
osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count, |
|
loff_t *ppos) |
|
{ |
|
struct trace_array *tr = osnoise_trace; |
|
cpumask_var_t osnoise_cpumask_new; |
|
int running, err; |
|
char buf[256]; |
|
|
|
if (count >= 256) |
|
return -EINVAL; |
|
|
|
if (copy_from_user(buf, ubuf, count)) |
|
return -EFAULT; |
|
|
|
if (!zalloc_cpumask_var(&osnoise_cpumask_new, GFP_KERNEL)) |
|
return -ENOMEM; |
|
|
|
err = cpulist_parse(buf, osnoise_cpumask_new); |
|
if (err) |
|
goto err_free; |
|
|
|
/* |
|
* trace_types_lock is taken to avoid concurrency on start/stop |
|
* and osnoise_busy. |
|
*/ |
|
mutex_lock(&trace_types_lock); |
|
running = osnoise_busy; |
|
if (running) |
|
osnoise_tracer_stop(tr); |
|
|
|
mutex_lock(&interface_lock); |
|
/* |
|
* osnoise_cpumask is read by CPU hotplug operations. |
|
*/ |
|
cpus_read_lock(); |
|
|
|
cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new); |
|
|
|
cpus_read_unlock(); |
|
mutex_unlock(&interface_lock); |
|
|
|
if (running) |
|
osnoise_tracer_start(tr); |
|
mutex_unlock(&trace_types_lock); |
|
|
|
free_cpumask_var(osnoise_cpumask_new); |
|
return count; |
|
|
|
err_free: |
|
free_cpumask_var(osnoise_cpumask_new); |
|
|
|
return err; |
|
} |
|
|
|
/* |
|
* osnoise/runtime_us: cannot be greater than the period. |
|
*/ |
|
static struct trace_min_max_param osnoise_runtime = { |
|
.lock = &interface_lock, |
|
.val = &osnoise_data.sample_runtime, |
|
.max = &osnoise_data.sample_period, |
|
.min = NULL, |
|
}; |
|
|
|
/* |
|
* osnoise/period_us: cannot be smaller than the runtime. |
|
*/ |
|
static struct trace_min_max_param osnoise_period = { |
|
.lock = &interface_lock, |
|
.val = &osnoise_data.sample_period, |
|
.max = NULL, |
|
.min = &osnoise_data.sample_runtime, |
|
}; |
|
|
|
/* |
|
* osnoise/stop_tracing_us: no limit. |
|
*/ |
|
static struct trace_min_max_param osnoise_stop_tracing_in = { |
|
.lock = &interface_lock, |
|
.val = &osnoise_data.stop_tracing, |
|
.max = NULL, |
|
.min = NULL, |
|
}; |
|
|
|
/* |
|
* osnoise/stop_tracing_total_us: no limit. |
|
*/ |
|
static struct trace_min_max_param osnoise_stop_tracing_total = { |
|
.lock = &interface_lock, |
|
.val = &osnoise_data.stop_tracing_total, |
|
.max = NULL, |
|
.min = NULL, |
|
}; |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
/* |
|
* osnoise/print_stack: print the stacktrace of the IRQ handler if the total |
|
* latency is higher than val. |
|
*/ |
|
static struct trace_min_max_param osnoise_print_stack = { |
|
.lock = &interface_lock, |
|
.val = &osnoise_data.print_stack, |
|
.max = NULL, |
|
.min = NULL, |
|
}; |
|
|
|
/* |
|
* osnoise/timerlat_period: min 100 us, max 1 s |
|
*/ |
|
u64 timerlat_min_period = 100; |
|
u64 timerlat_max_period = 1000000; |
|
static struct trace_min_max_param timerlat_period = { |
|
.lock = &interface_lock, |
|
.val = &osnoise_data.timerlat_period, |
|
.max = &timerlat_max_period, |
|
.min = &timerlat_min_period, |
|
}; |
|
#endif |
|
|
|
static const struct file_operations cpus_fops = { |
|
.open = tracing_open_generic, |
|
.read = osnoise_cpus_read, |
|
.write = osnoise_cpus_write, |
|
.llseek = generic_file_llseek, |
|
}; |
|
|
|
/* |
|
* init_tracefs - A function to initialize the tracefs interface files |
|
* |
|
* This function creates entries in tracefs for "osnoise" and "timerlat". |
|
* It creates these directories in the tracing directory, and within that |
|
* directory the use can change and view the configs. |
|
*/ |
|
static int init_tracefs(void) |
|
{ |
|
struct dentry *top_dir; |
|
struct dentry *tmp; |
|
int ret; |
|
|
|
ret = tracing_init_dentry(); |
|
if (ret) |
|
return -ENOMEM; |
|
|
|
top_dir = tracefs_create_dir("osnoise", NULL); |
|
if (!top_dir) |
|
return 0; |
|
|
|
tmp = tracefs_create_file("period_us", 0640, top_dir, |
|
&osnoise_period, &trace_min_max_fops); |
|
if (!tmp) |
|
goto err; |
|
|
|
tmp = tracefs_create_file("runtime_us", 0644, top_dir, |
|
&osnoise_runtime, &trace_min_max_fops); |
|
if (!tmp) |
|
goto err; |
|
|
|
tmp = tracefs_create_file("stop_tracing_us", 0640, top_dir, |
|
&osnoise_stop_tracing_in, &trace_min_max_fops); |
|
if (!tmp) |
|
goto err; |
|
|
|
tmp = tracefs_create_file("stop_tracing_total_us", 0640, top_dir, |
|
&osnoise_stop_tracing_total, &trace_min_max_fops); |
|
if (!tmp) |
|
goto err; |
|
|
|
tmp = trace_create_file("cpus", 0644, top_dir, NULL, &cpus_fops); |
|
if (!tmp) |
|
goto err; |
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
#ifdef CONFIG_STACKTRACE |
|
tmp = tracefs_create_file("print_stack", 0640, top_dir, |
|
&osnoise_print_stack, &trace_min_max_fops); |
|
if (!tmp) |
|
goto err; |
|
#endif |
|
|
|
tmp = tracefs_create_file("timerlat_period_us", 0640, top_dir, |
|
&timerlat_period, &trace_min_max_fops); |
|
if (!tmp) |
|
goto err; |
|
#endif |
|
|
|
return 0; |
|
|
|
err: |
|
tracefs_remove(top_dir); |
|
return -ENOMEM; |
|
} |
|
|
|
static int osnoise_hook_events(void) |
|
{ |
|
int retval; |
|
|
|
/* |
|
* Trace is already hooked, we are re-enabling from |
|
* a stop_tracing_*. |
|
*/ |
|
if (trace_osnoise_callback_enabled) |
|
return 0; |
|
|
|
retval = hook_irq_events(); |
|
if (retval) |
|
return -EINVAL; |
|
|
|
retval = hook_softirq_events(); |
|
if (retval) |
|
goto out_unhook_irq; |
|
|
|
retval = hook_thread_events(); |
|
/* |
|
* All fine! |
|
*/ |
|
if (!retval) |
|
return 0; |
|
|
|
unhook_softirq_events(); |
|
out_unhook_irq: |
|
unhook_irq_events(); |
|
return -EINVAL; |
|
} |
|
|
|
static int __osnoise_tracer_start(struct trace_array *tr) |
|
{ |
|
int retval; |
|
|
|
osn_var_reset_all(); |
|
|
|
retval = osnoise_hook_events(); |
|
if (retval) |
|
return retval; |
|
/* |
|
* Make sure NMIs see reseted values. |
|
*/ |
|
barrier(); |
|
trace_osnoise_callback_enabled = true; |
|
|
|
retval = start_per_cpu_kthreads(tr); |
|
if (retval) { |
|
unhook_irq_events(); |
|
return retval; |
|
} |
|
|
|
osnoise_busy = true; |
|
|
|
return 0; |
|
} |
|
|
|
static void osnoise_tracer_start(struct trace_array *tr) |
|
{ |
|
int retval; |
|
|
|
if (osnoise_busy) |
|
return; |
|
|
|
retval = __osnoise_tracer_start(tr); |
|
if (retval) |
|
pr_err(BANNER "Error starting osnoise tracer\n"); |
|
|
|
} |
|
|
|
static void osnoise_tracer_stop(struct trace_array *tr) |
|
{ |
|
if (!osnoise_busy) |
|
return; |
|
|
|
trace_osnoise_callback_enabled = false; |
|
barrier(); |
|
|
|
stop_per_cpu_kthreads(); |
|
|
|
unhook_irq_events(); |
|
unhook_softirq_events(); |
|
unhook_thread_events(); |
|
|
|
osnoise_busy = false; |
|
} |
|
|
|
static int osnoise_tracer_init(struct trace_array *tr) |
|
{ |
|
|
|
/* Only allow one instance to enable this */ |
|
if (osnoise_busy) |
|
return -EBUSY; |
|
|
|
osnoise_trace = tr; |
|
tr->max_latency = 0; |
|
|
|
osnoise_tracer_start(tr); |
|
|
|
return 0; |
|
} |
|
|
|
static void osnoise_tracer_reset(struct trace_array *tr) |
|
{ |
|
osnoise_tracer_stop(tr); |
|
} |
|
|
|
static struct tracer osnoise_tracer __read_mostly = { |
|
.name = "osnoise", |
|
.init = osnoise_tracer_init, |
|
.reset = osnoise_tracer_reset, |
|
.start = osnoise_tracer_start, |
|
.stop = osnoise_tracer_stop, |
|
.print_header = print_osnoise_headers, |
|
.allow_instances = true, |
|
}; |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
static void timerlat_tracer_start(struct trace_array *tr) |
|
{ |
|
int retval; |
|
|
|
if (osnoise_busy) |
|
return; |
|
|
|
osnoise_data.timerlat_tracer = 1; |
|
|
|
retval = __osnoise_tracer_start(tr); |
|
if (retval) |
|
goto out_err; |
|
|
|
return; |
|
out_err: |
|
pr_err(BANNER "Error starting timerlat tracer\n"); |
|
} |
|
|
|
static void timerlat_tracer_stop(struct trace_array *tr) |
|
{ |
|
int cpu; |
|
|
|
if (!osnoise_busy) |
|
return; |
|
|
|
for_each_online_cpu(cpu) |
|
per_cpu(per_cpu_osnoise_var, cpu).sampling = 0; |
|
|
|
osnoise_tracer_stop(tr); |
|
|
|
osnoise_data.timerlat_tracer = 0; |
|
} |
|
|
|
static int timerlat_tracer_init(struct trace_array *tr) |
|
{ |
|
/* Only allow one instance to enable this */ |
|
if (osnoise_busy) |
|
return -EBUSY; |
|
|
|
osnoise_trace = tr; |
|
|
|
tr->max_latency = 0; |
|
|
|
timerlat_tracer_start(tr); |
|
|
|
return 0; |
|
} |
|
|
|
static void timerlat_tracer_reset(struct trace_array *tr) |
|
{ |
|
timerlat_tracer_stop(tr); |
|
} |
|
|
|
static struct tracer timerlat_tracer __read_mostly = { |
|
.name = "timerlat", |
|
.init = timerlat_tracer_init, |
|
.reset = timerlat_tracer_reset, |
|
.start = timerlat_tracer_start, |
|
.stop = timerlat_tracer_stop, |
|
.print_header = print_timerlat_headers, |
|
.allow_instances = true, |
|
}; |
|
#endif /* CONFIG_TIMERLAT_TRACER */ |
|
|
|
__init static int init_osnoise_tracer(void) |
|
{ |
|
int ret; |
|
|
|
mutex_init(&interface_lock); |
|
|
|
cpumask_copy(&osnoise_cpumask, cpu_all_mask); |
|
|
|
ret = register_tracer(&osnoise_tracer); |
|
if (ret) { |
|
pr_err(BANNER "Error registering osnoise!\n"); |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_TIMERLAT_TRACER |
|
ret = register_tracer(&timerlat_tracer); |
|
if (ret) { |
|
pr_err(BANNER "Error registering timerlat\n"); |
|
return ret; |
|
} |
|
#endif |
|
osnoise_init_hotplug_support(); |
|
|
|
init_tracefs(); |
|
|
|
return 0; |
|
} |
|
late_initcall(init_osnoise_tracer);
|
|
|