diff options
Diffstat (limited to 'tools/tracing/latency')
| -rw-r--r-- | tools/tracing/latency/.gitignore | 2 | ||||
| -rw-r--r-- | tools/tracing/latency/Makefile | 24 | ||||
| -rw-r--r-- | tools/tracing/latency/latency-collector.c | 2108 |
3 files changed, 2134 insertions, 0 deletions
diff --git a/tools/tracing/latency/.gitignore b/tools/tracing/latency/.gitignore new file mode 100644 index 0000000000..0863960761 --- /dev/null +++ b/tools/tracing/latency/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0 +latency-collector diff --git a/tools/tracing/latency/Makefile b/tools/tracing/latency/Makefile new file mode 100644 index 0000000000..40c4ddaf8b --- /dev/null +++ b/tools/tracing/latency/Makefile @@ -0,0 +1,24 @@ +# SPDX-License-Identifier: GPL-2.0 +# Makefile for vm tools +# +VAR_CFLAGS := $(shell pkg-config --cflags libtracefs 2>/dev/null) +VAR_LDLIBS := $(shell pkg-config --libs libtracefs 2>/dev/null) + +TARGETS = latency-collector +CFLAGS = -Wall -Wextra -g -O2 $(VAR_CFLAGS) +LDFLAGS = -lpthread $(VAR_LDLIBS) + +all: $(TARGETS) + +%: %.c + $(CC) $(CFLAGS) -o $@ $< $(LDFLAGS) + +clean: + $(RM) latency-collector + +prefix ?= /usr/local +sbindir ?= ${prefix}/sbin + +install: all + install -d $(DESTDIR)$(sbindir) + install -m 755 -p $(TARGETS) $(DESTDIR)$(sbindir) diff --git a/tools/tracing/latency/latency-collector.c b/tools/tracing/latency/latency-collector.c new file mode 100644 index 0000000000..0fd9c747d3 --- /dev/null +++ b/tools/tracing/latency/latency-collector.c @@ -0,0 +1,2108 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017, 2018, 2019, 2021 BMW Car IT GmbH + * Author: Viktor Rosendahl (viktor.rosendahl@bmw.de) + */ + +#define _GNU_SOURCE +#define _POSIX_C_SOURCE 200809L + +#include <ctype.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include <err.h> +#include <errno.h> +#include <fcntl.h> +#include <getopt.h> +#include <sched.h> +#include <linux/unistd.h> +#include <signal.h> +#include <sys/inotify.h> +#include <unistd.h> +#include <pthread.h> +#include <tracefs.h> + +static const char *prg_name; +static const char *prg_unknown = "unknown program name"; + +static int fd_stdout; + +static int sched_policy; +static bool sched_policy_set; + +static int sched_pri; +static bool sched_pri_set; + +static bool trace_enable = true; +static bool setup_ftrace = true; +static bool use_random_sleep; + +#define TRACE_OPTS \ + C(FUNC_TR, "function-trace"), \ + C(DISP_GR, "display-graph"), \ + C(NR, NULL) + +#undef C +#define C(a, b) OPTIDX_##a + +enum traceopt { + TRACE_OPTS +}; + +#undef C +#define C(a, b) b + +static const char *const optstr[] = { + TRACE_OPTS +}; + +enum errhandling { + ERR_EXIT = 0, + ERR_WARN, + ERR_CLEANUP, +}; + +static bool use_options[OPTIDX_NR]; + +static char inotify_buffer[655360]; + +#define likely(x) __builtin_expect(!!(x), 1) +#define unlikely(x) __builtin_expect(!!(x), 0) +#define bool2str(x) (x ? "true":"false") + +#define DEFAULT_NR_PRINTER_THREADS (3) +static unsigned int nr_threads = DEFAULT_NR_PRINTER_THREADS; + +#define DEFAULT_TABLE_SIZE (2) +static unsigned int table_startsize = DEFAULT_TABLE_SIZE; + +static int verbosity; + +#define verbose_sizechange() (verbosity >= 1) +#define verbose_lostevent() (verbosity >= 2) +#define verbose_ftrace() (verbosity >= 1) + +#define was_changed(ORIG, CUR) (strcmp(ORIG, CUR) != 0) +#define needs_change(CUR, WANTED) (strcmp(CUR, WANTED) != 0) + +static const char *debug_tracefile; +static const char *debug_tracefile_dflt; +static const char *debug_maxlat; +static const char *debug_maxlat_dflt; +static const char * const DEBUG_NOFILE = "[file not found]"; + +static const char * const TR_MAXLAT = "tracing_max_latency"; +static const char * const TR_THRESH = "tracing_thresh"; +static const char * const TR_CURRENT = "current_tracer"; +static const char * const TR_OPTIONS = "trace_options"; + +static const char * const NOP_TRACER = "nop"; + +static const char * const OPT_NO_PREFIX = "no"; + +#define DFLT_THRESHOLD_US "0" +static const char *threshold = DFLT_THRESHOLD_US; + +#define DEV_URANDOM "/dev/urandom" +#define RT_DEFAULT_PRI (99) +#define DEFAULT_PRI (0) + +#define USEC_PER_MSEC (1000L) +#define NSEC_PER_USEC (1000L) +#define NSEC_PER_MSEC (USEC_PER_MSEC * NSEC_PER_USEC) + +#define MSEC_PER_SEC (1000L) +#define USEC_PER_SEC (USEC_PER_MSEC * MSEC_PER_SEC) +#define NSEC_PER_SEC (NSEC_PER_MSEC * MSEC_PER_SEC) + +#define SLEEP_TIME_MS_DEFAULT (1000L) +#define TRY_PRINTMUTEX_MS (1000) + +static long sleep_time = (USEC_PER_MSEC * SLEEP_TIME_MS_DEFAULT); + +static const char * const queue_full_warning = +"Could not queue trace for printing. It is likely that events happen faster\n" +"than what they can be printed. Probably partly because of random sleeping\n"; + +static const char * const no_tracer_msg = +"Could not find any tracers! Running this program as root may help!\n"; + +static const char * const no_latency_tr_msg = +"No latency tracers are supported by your kernel!\n"; + +struct policy { + const char *name; + int policy; + int default_pri; +}; + +static const struct policy policies[] = { + { "other", SCHED_OTHER, DEFAULT_PRI }, + { "batch", SCHED_BATCH, DEFAULT_PRI }, + { "idle", SCHED_IDLE, DEFAULT_PRI }, + { "rr", SCHED_RR, RT_DEFAULT_PRI }, + { "fifo", SCHED_FIFO, RT_DEFAULT_PRI }, + { NULL, 0, DEFAULT_PRI } +}; + +/* + * The default tracer will be the first on this list that is supported by the + * currently running Linux kernel. + */ +static const char * const relevant_tracers[] = { + "preemptirqsoff", + "preemptoff", + "irqsoff", + "wakeup", + "wakeup_rt", + "wakeup_dl", + NULL +}; + +/* This is the list of tracers for which random sleep makes sense */ +static const char * const random_tracers[] = { + "preemptirqsoff", + "preemptoff", + "irqsoff", + NULL +}; + +static const char *current_tracer; +static bool force_tracer; + +struct ftrace_state { + char *tracer; + char *thresh; + bool opt[OPTIDX_NR]; + bool opt_valid[OPTIDX_NR]; + pthread_mutex_t mutex; +}; + +struct entry { + int ticket; + int ticket_completed_ref; +}; + +struct print_state { + int ticket_counter; + int ticket_completed; + pthread_mutex_t mutex; + pthread_cond_t cond; + int cnt; + pthread_mutex_t cnt_mutex; +}; + +struct short_msg { + char buf[160]; + int len; +}; + +static struct print_state printstate; +static struct ftrace_state save_state; +volatile sig_atomic_t signal_flag; + +#define PROB_TABLE_MAX_SIZE (1000) + +int probabilities[PROB_TABLE_MAX_SIZE]; + +struct sleep_table { + int *table; + int size; + pthread_mutex_t mutex; +}; + +static struct sleep_table sleeptable; + +#define QUEUE_SIZE (10) + +struct queue { + struct entry entries[QUEUE_SIZE]; + int next_prod_idx; + int next_cons_idx; + pthread_mutex_t mutex; + pthread_cond_t cond; +}; + +#define MAX_THREADS (40) + +struct queue printqueue; +pthread_t printthread[MAX_THREADS]; +pthread_mutex_t print_mtx; +#define PRINT_BUFFER_SIZE (16 * 1024 * 1024) + +static void cleanup_exit(int status); +static int set_trace_opt(const char *opt, bool value); + +static __always_inline void *malloc_or_die(size_t size) +{ + void *ptr = malloc(size); + + if (unlikely(ptr == NULL)) { + warn("malloc() failed"); + cleanup_exit(EXIT_FAILURE); + } + return ptr; +} + +static __always_inline void *malloc_or_die_nocleanup(size_t size) +{ + void *ptr = malloc(size); + + if (unlikely(ptr == NULL)) + err(0, "malloc() failed"); + return ptr; +} + +static __always_inline void write_or_die(int fd, const char *buf, size_t count) +{ + ssize_t r; + + do { + r = write(fd, buf, count); + if (unlikely(r < 0)) { + if (errno == EINTR) + continue; + warn("write() failed"); + cleanup_exit(EXIT_FAILURE); + } + count -= r; + buf += r; + } while (count > 0); +} + +static __always_inline void clock_gettime_or_die(clockid_t clk_id, + struct timespec *tp) +{ + int r = clock_gettime(clk_id, tp); + + if (unlikely(r != 0)) + err(EXIT_FAILURE, "clock_gettime() failed"); +} + +static __always_inline void sigemptyset_or_die(sigset_t *s) +{ + if (unlikely(sigemptyset(s) != 0)) { + warn("sigemptyset() failed"); + cleanup_exit(EXIT_FAILURE); + } +} + +static __always_inline void sigaddset_or_die(sigset_t *s, int signum) +{ + if (unlikely(sigaddset(s, signum) != 0)) { + warn("sigemptyset() failed"); + cleanup_exit(EXIT_FAILURE); + } +} + +static __always_inline void sigaction_or_die(int signum, + const struct sigaction *act, + struct sigaction *oldact) +{ + if (unlikely(sigaction(signum, act, oldact) != 0)) { + warn("sigaction() failed"); + cleanup_exit(EXIT_FAILURE); + } +} + +static void open_stdout(void) +{ + if (setvbuf(stdout, NULL, _IONBF, 0) != 0) + err(EXIT_FAILURE, "setvbuf() failed"); + fd_stdout = fileno(stdout); + if (fd_stdout < 0) + err(EXIT_FAILURE, "fileno() failed"); +} + +/* + * It's not worth it to call cleanup_exit() from mutex functions because + * cleanup_exit() uses mutexes. + */ +static __always_inline void mutex_lock(pthread_mutex_t *mtx) +{ + errno = pthread_mutex_lock(mtx); + if (unlikely(errno)) + err(EXIT_FAILURE, "pthread_mutex_lock() failed"); +} + + +static __always_inline void mutex_unlock(pthread_mutex_t *mtx) +{ + errno = pthread_mutex_unlock(mtx); + if (unlikely(errno)) + err(EXIT_FAILURE, "pthread_mutex_unlock() failed"); +} + +static __always_inline void cond_signal(pthread_cond_t *cond) +{ + errno = pthread_cond_signal(cond); + if (unlikely(errno)) + err(EXIT_FAILURE, "pthread_cond_signal() failed"); +} + +static __always_inline void cond_wait(pthread_cond_t *restrict cond, + pthread_mutex_t *restrict mutex) +{ + errno = pthread_cond_wait(cond, mutex); + if (unlikely(errno)) + err(EXIT_FAILURE, "pthread_cond_wait() failed"); +} + +static __always_inline void cond_broadcast(pthread_cond_t *cond) +{ + errno = pthread_cond_broadcast(cond); + if (unlikely(errno)) + err(EXIT_FAILURE, "pthread_cond_broadcast() failed"); +} + +static __always_inline void +mutex_init(pthread_mutex_t *mutex, + const pthread_mutexattr_t *attr) +{ + errno = pthread_mutex_init(mutex, attr); + if (errno) + err(EXIT_FAILURE, "pthread_mutex_init() failed"); +} + +static __always_inline void mutexattr_init(pthread_mutexattr_t *attr) +{ + errno = pthread_mutexattr_init(attr); + if (errno) + err(EXIT_FAILURE, "pthread_mutexattr_init() failed"); +} + +static __always_inline void mutexattr_destroy(pthread_mutexattr_t *attr) +{ + errno = pthread_mutexattr_destroy(attr); + if (errno) + err(EXIT_FAILURE, "pthread_mutexattr_destroy() failed"); +} + +static __always_inline void mutexattr_settype(pthread_mutexattr_t *attr, + int type) +{ + errno = pthread_mutexattr_settype(attr, type); + if (errno) + err(EXIT_FAILURE, "pthread_mutexattr_settype() failed"); +} + +static __always_inline void condattr_init(pthread_condattr_t *attr) +{ + errno = pthread_condattr_init(attr); + if (errno) + err(EXIT_FAILURE, "pthread_condattr_init() failed"); +} + +static __always_inline void condattr_destroy(pthread_condattr_t *attr) +{ + errno = pthread_condattr_destroy(attr); + if (errno) + err(EXIT_FAILURE, "pthread_condattr_destroy() failed"); +} + +static __always_inline void condattr_setclock(pthread_condattr_t *attr, + clockid_t clock_id) +{ + errno = pthread_condattr_setclock(attr, clock_id); + if (unlikely(errno)) + err(EXIT_FAILURE, "pthread_condattr_setclock() failed"); +} + +static __always_inline void cond_init(pthread_cond_t *cond, + const pthread_condattr_t *attr) +{ + errno = pthread_cond_init(cond, attr); + if (errno) + err(EXIT_FAILURE, "pthread_cond_init() failed"); +} + +static __always_inline int +cond_timedwait(pthread_cond_t *restrict cond, + pthread_mutex_t *restrict mutex, + const struct timespec *restrict abstime) +{ + errno = pthread_cond_timedwait(cond, mutex, abstime); + if (errno && errno != ETIMEDOUT) + err(EXIT_FAILURE, "pthread_cond_timedwait() failed"); + return errno; +} + +static void init_printstate(void) +{ + pthread_condattr_t cattr; + + printstate.ticket_counter = 0; + printstate.ticket_completed = 0; + printstate.cnt = 0; + + mutex_init(&printstate.mutex, NULL); + + condattr_init(&cattr); + condattr_setclock(&cattr, CLOCK_MONOTONIC); + cond_init(&printstate.cond, &cattr); + condattr_destroy(&cattr); +} + +static void init_print_mtx(void) +{ + pthread_mutexattr_t mattr; + + mutexattr_init(&mattr); + mutexattr_settype(&mattr, PTHREAD_MUTEX_RECURSIVE); + mutex_init(&print_mtx, &mattr); + mutexattr_destroy(&mattr); + +} + +static void signal_blocking(int how) +{ + sigset_t s; + + sigemptyset_or_die(&s); + sigaddset_or_die(&s, SIGHUP); + sigaddset_or_die(&s, SIGTERM); + sigaddset_or_die(&s, SIGINT); + + errno = pthread_sigmask(how, &s, NULL); + if (unlikely(errno)) { + warn("pthread_sigmask() failed"); + cleanup_exit(EXIT_FAILURE); + } +} + +static void signal_handler(int num) +{ + signal_flag = num; +} + +static void setup_sig_handler(void) +{ + struct sigaction sa; + + memset(&sa, 0, sizeof(sa)); + sa.sa_handler = signal_handler; + + sigaction_or_die(SIGHUP, &sa, NULL); + sigaction_or_die(SIGTERM, &sa, NULL); + sigaction_or_die(SIGINT, &sa, NULL); +} + +static void process_signal(int signal) +{ + char *name; + + name = strsignal(signal); + if (name == NULL) + printf("Received signal %d\n", signal); + else + printf("Received signal %d (%s)\n", signal, name); + cleanup_exit(EXIT_SUCCESS); +} + +static __always_inline void check_signals(void) +{ + int signal = signal_flag; + + if (unlikely(signal)) + process_signal(signal); +} + +static __always_inline void get_time_in_future(struct timespec *future, + long time_us) +{ + long nsec; + + clock_gettime_or_die(CLOCK_MONOTONIC, future); + future->tv_sec += time_us / USEC_PER_SEC; + nsec = future->tv_nsec + (time_us * NSEC_PER_USEC) % NSEC_PER_SEC; + if (nsec >= NSEC_PER_SEC) { + future->tv_nsec = nsec % NSEC_PER_SEC; + future->tv_sec += 1; + } +} + +static __always_inline bool time_has_passed(const struct timespec *time) +{ + struct timespec now; + + clock_gettime_or_die(CLOCK_MONOTONIC, &now); + if (now.tv_sec > time->tv_sec) + return true; + if (now.tv_sec < time->tv_sec) + return false; + return (now.tv_nsec >= time->tv_nsec); +} + +static bool mutex_trylock_limit(pthread_mutex_t *mutex, int time_ms) +{ + long time_us = time_ms * USEC_PER_MSEC; + struct timespec limit; + + get_time_in_future(&limit, time_us); + do { + errno = pthread_mutex_trylock(mutex); + if (errno && errno != EBUSY) + err(EXIT_FAILURE, "pthread_mutex_trylock() failed"); + } while (errno && !time_has_passed(&limit)); + return errno == 0; +} + +static void restore_trace_opts(const struct ftrace_state *state, + const bool *cur) +{ + int i; + int r; + + for (i = 0; i < OPTIDX_NR; i++) + if (state->opt_valid[i] && state->opt[i] != cur[i]) { + r = set_trace_opt(optstr[i], state->opt[i]); + if (r < 0) + warnx("Failed to restore the %s option to %s", + optstr[i], bool2str(state->opt[i])); + else if (verbose_ftrace()) + printf("Restored the %s option in %s to %s\n", + optstr[i], TR_OPTIONS, + bool2str(state->opt[i])); + } +} + +static char *read_file(const char *file, enum errhandling h) +{ + int psize; + char *r; + static const char *emsg = "Failed to read the %s file"; + + r = tracefs_instance_file_read(NULL, file, &psize); + if (!r) { + if (h) { + warn(emsg, file); + if (h == ERR_CLEANUP) + cleanup_exit(EXIT_FAILURE); + } else + errx(EXIT_FAILURE, emsg, file); + } + + if (r && r[psize - 1] == '\n') + r[psize - 1] = '\0'; + return r; +} + +static void restore_file(const char *file, char **saved, const char *cur) +{ + if (*saved && was_changed(*saved, cur)) { + if (tracefs_instance_file_write(NULL, file, *saved) < 0) + warnx("Failed to restore %s to %s!", file, *saved); + else if (verbose_ftrace()) + printf("Restored %s to %s\n", file, *saved); + free(*saved); + *saved = NULL; + } +} + +static void restore_ftrace(void) +{ + mutex_lock(&save_state.mutex); + + restore_file(TR_CURRENT, &save_state.tracer, current_tracer); + restore_file(TR_THRESH, &save_state.thresh, threshold); + restore_trace_opts(&save_state, use_options); + + mutex_unlock(&save_state.mutex); +} + +static void cleanup_exit(int status) +{ + char *maxlat; + + if (!setup_ftrace) + exit(status); + + /* + * We try the print_mtx for 1 sec in order to avoid garbled + * output if possible, but if it cannot be obtained we proceed anyway. + */ + mutex_trylock_limit(&print_mtx, TRY_PRINTMUTEX_MS); + + maxlat = read_file(TR_MAXLAT, ERR_WARN); + if (maxlat) { + printf("The maximum detected latency was: %sus\n", maxlat); + free(maxlat); + } + + restore_ftrace(); + /* + * We do not need to unlock the print_mtx here because we will exit at + * the end of this function. Unlocking print_mtx causes problems if a + * print thread happens to be waiting for the mutex because we have + * just changed the ftrace settings to the original and thus the + * print thread would output incorrect data from ftrace. + */ + exit(status); +} + +static void init_save_state(void) +{ + pthread_mutexattr_t mattr; + + mutexattr_init(&mattr); + mutexattr_settype(&mattr, PTHREAD_MUTEX_RECURSIVE); + mutex_init(&save_state.mutex, &mattr); + mutexattr_destroy(&mattr); + + save_state.tracer = NULL; + save_state.thresh = NULL; + save_state.opt_valid[OPTIDX_FUNC_TR] = false; + save_state.opt_valid[OPTIDX_DISP_GR] = false; +} + +static int printstate_next_ticket(struct entry *req) +{ + int r; + + r = ++(printstate.ticket_counter); + req->ticket = r; + req->ticket_completed_ref = printstate.ticket_completed; + cond_broadcast(&printstate.cond); + return r; +} + +static __always_inline +void printstate_mark_req_completed(const struct entry *req) +{ + if (req->ticket > printstate.ticket_completed) + printstate.ticket_completed = req->ticket; +} + +static __always_inline +bool printstate_has_new_req_arrived(const struct entry *req) +{ + return (printstate.ticket_counter != req->ticket); +} + +static __always_inline int printstate_cnt_inc(void) +{ + int value; + + mutex_lock(&printstate.cnt_mutex); + value = ++printstate.cnt; + mutex_unlock(&printstate.cnt_mutex); + return value; +} + +static __always_inline int printstate_cnt_dec(void) +{ + int value; + + mutex_lock(&printstate.cnt_mutex); + value = --printstate.cnt; + mutex_unlock(&printstate.cnt_mutex); + return value; +} + +static __always_inline int printstate_cnt_read(void) +{ + int value; + + mutex_lock(&printstate.cnt_mutex); + value = printstate.cnt; + mutex_unlock(&printstate.cnt_mutex); + return value; +} + +static __always_inline +bool prev_req_won_race(const struct entry *req) +{ + return (printstate.ticket_completed != req->ticket_completed_ref); +} + +static void sleeptable_resize(int size, bool printout, struct short_msg *msg) +{ + int bytes; + + if (printout) { + msg->len = 0; + if (unlikely(size > PROB_TABLE_MAX_SIZE)) + bytes = snprintf(msg->buf, sizeof(msg->buf), +"Cannot increase probability table to %d (maximum size reached)\n", size); + else + bytes = snprintf(msg->buf, sizeof(msg->buf), +"Increasing probability table to %d\n", size); + if (bytes < 0) + warn("snprintf() failed"); + else + msg->len = bytes; + } + + if (unlikely(size < 0)) { + /* Should never happen */ + warnx("Bad program state at %s:%d", __FILE__, __LINE__); + cleanup_exit(EXIT_FAILURE); + return; + } + sleeptable.size = size; + sleeptable.table = &probabilities[PROB_TABLE_MAX_SIZE - size]; +} + +static void init_probabilities(void) +{ + int i; + int j = 1000; + + for (i = 0; i < PROB_TABLE_MAX_SIZE; i++) { + probabilities[i] = 1000 / j; + j--; + } + mutex_init(&sleeptable.mutex, NULL); +} + +static int table_get_probability(const struct entry *req, + struct short_msg *msg) +{ + int diff = req->ticket - req->ticket_completed_ref; + int rval = 0; + + msg->len = 0; + diff--; + /* Should never happen...*/ + if (unlikely(diff < 0)) { + warnx("Programmer assumption error at %s:%d\n", __FILE__, + __LINE__); + cleanup_exit(EXIT_FAILURE); + } + mutex_lock(&sleeptable.mutex); + if (diff >= (sleeptable.size - 1)) { + rval = sleeptable.table[sleeptable.size - 1]; + sleeptable_resize(sleeptable.size + 1, verbose_sizechange(), + msg); + } else { + rval = sleeptable.table[diff]; + } + mutex_unlock(&sleeptable.mutex); + return rval; +} + +static void init_queue(struct queue *q) +{ + q->next_prod_idx = 0; + q->next_cons_idx = 0; + mutex_init(&q->mutex, NULL); + errno = pthread_cond_init(&q->cond, NULL); + if (errno) + err(EXIT_FAILURE, "pthread_cond_init() failed"); +} + +static __always_inline int queue_len(const struct queue *q) +{ + if (q->next_prod_idx >= q->next_cons_idx) + return q->next_prod_idx - q->next_cons_idx; + else + return QUEUE_SIZE - q->next_cons_idx + q->next_prod_idx; +} + +static __always_inline int queue_nr_free(const struct queue *q) +{ + int nr_free = QUEUE_SIZE - queue_len(q); + + /* + * If there is only one slot left we will anyway lie and claim that the + * queue is full because adding an element will make it appear empty + */ + if (nr_free == 1) + nr_free = 0; + return nr_free; +} + +static __always_inline void queue_idx_inc(int *idx) +{ + *idx = (*idx + 1) % QUEUE_SIZE; +} + +static __always_inline void queue_push_to_back(struct queue *q, + const struct entry *e) +{ + q->entries[q->next_prod_idx] = *e; + queue_idx_inc(&q->next_prod_idx); +} + +static __always_inline struct entry queue_pop_from_front(struct queue *q) +{ + struct entry e = q->entries[q->next_cons_idx]; + + queue_idx_inc(&q->next_cons_idx); + return e; +} + +static __always_inline void queue_cond_signal(struct queue *q) +{ + cond_signal(&q->cond); +} + +static __always_inline void queue_cond_wait(struct queue *q) +{ + cond_wait(&q->cond, &q->mutex); +} + +static __always_inline int queue_try_to_add_entry(struct queue *q, + const struct entry *e) +{ + int r = 0; + + mutex_lock(&q->mutex); + if (queue_nr_free(q) > 0) { + queue_push_to_back(q, e); + cond_signal(&q->cond); + } else + r = -1; + mutex_unlock(&q->mutex); + return r; +} + +static struct entry queue_wait_for_entry(struct queue *q) +{ + struct entry e; + + mutex_lock(&q->mutex); + while (true) { + if (queue_len(&printqueue) > 0) { + e = queue_pop_from_front(q); + break; + } + queue_cond_wait(q); + } + mutex_unlock(&q->mutex); + + return e; +} + +static const struct policy *policy_from_name(const char *name) +{ + const struct policy *p = &policies[0]; + + while (p->name != NULL) { + if (!strcmp(name, p->name)) + return p; + p++; + } + return NULL; +} + +static const char *policy_name(int policy) +{ + const struct policy *p = &policies[0]; + static const char *rval = "unknown"; + + while (p->name != NULL) { + if (p->policy == policy) + return p->name; + p++; + } + return rval; +} + +static bool is_relevant_tracer(const char *name) +{ + unsigned int i; + + for (i = 0; relevant_tracers[i]; i++) + if (!strcmp(name, relevant_tracers[i])) + return true; + return false; +} + +static bool random_makes_sense(const char *name) +{ + unsigned int i; + + for (i = 0; random_tracers[i]; i++) + if (!strcmp(name, random_tracers[i])) + return true; + return false; +} + +static void show_available(void) +{ + char **tracers; + int found = 0; + int i; + + tracers = tracefs_tracers(NULL); + for (i = 0; tracers && tracers[i]; i++) { + if (is_relevant_tracer(tracers[i])) + found++; + } + + if (!tracers) { + warnx(no_tracer_msg); + return; + } + + if (!found) { + warnx(no_latency_tr_msg); + tracefs_list_free(tracers); + return; + } + + printf("The following latency tracers are available on your system:\n"); + for (i = 0; tracers[i]; i++) { + if (is_relevant_tracer(tracers[i])) + printf("%s\n", tracers[i]); + } + tracefs_list_free(tracers); +} + +static bool tracer_valid(const char *name, bool *notracer) +{ + char **tracers; + int i; + bool rval = false; + + *notracer = false; + tracers = tracefs_tracers(NULL); + if (!tracers) { + *notracer = true; + return false; + } + for (i = 0; tracers[i]; i++) + if (!strcmp(tracers[i], name)) { + rval = true; + break; + } + tracefs_list_free(tracers); + return rval; +} + +static const char *find_default_tracer(void) +{ + int i; + bool notracer; + bool valid; + + for (i = 0; relevant_tracers[i]; i++) { + valid = tracer_valid(relevant_tracers[i], ¬racer); + if (notracer) + errx(EXIT_FAILURE, no_tracer_msg); + if (valid) + return relevant_tracers[i]; + } + return NULL; +} + +static bool toss_coin(struct drand48_data *buffer, unsigned int prob) +{ + long r; + + if (unlikely(lrand48_r(buffer, &r))) { + warnx("lrand48_r() failed"); + cleanup_exit(EXIT_FAILURE); + } + r = r % 1000L; + if (r < prob) + return true; + else + return false; +} + + +static long go_to_sleep(const struct entry *req) +{ + struct timespec future; + long delay = sleep_time; + + get_time_in_future(&future, delay); + + mutex_lock(&printstate.mutex); + while (!printstate_has_new_req_arrived(req)) { + cond_timedwait(&printstate.cond, &printstate.mutex, &future); + if (time_has_passed(&future)) + break; + } + + if (printstate_has_new_req_arrived(req)) + delay = -1; + mutex_unlock(&printstate.mutex); + + return delay; +} + + +static void set_priority(void) +{ + int r; + pid_t pid; + struct sched_param param; + + memset(¶m, 0, sizeof(param)); + param.sched_priority = sched_pri; + + pid = getpid(); + r = sched_setscheduler(pid, sched_policy, ¶m); + + if (r != 0) + err(EXIT_FAILURE, "sched_setscheduler() failed"); +} + +pid_t latency_collector_gettid(void) +{ + return (pid_t) syscall(__NR_gettid); +} + +static void print_priority(void) +{ + pid_t tid; + int policy; + int r; + struct sched_param param; + + tid = latency_collector_gettid(); + r = pthread_getschedparam(pthread_self(), &policy, ¶m); + if (r != 0) { + warn("pthread_getschedparam() failed"); + cleanup_exit(EXIT_FAILURE); + } + mutex_lock(&print_mtx); + printf("Thread %d runs with scheduling policy %s and priority %d\n", + tid, policy_name(policy), param.sched_priority); + mutex_unlock(&print_mtx); +} + +static __always_inline +void __print_skipmessage(const struct short_msg *resize_msg, + const struct timespec *timestamp, char *buffer, + size_t bufspace, const struct entry *req, bool excuse, + const char *str) +{ + ssize_t bytes = 0; + char *p = &buffer[0]; + long us, sec; + int r; + + sec = timestamp->tv_sec; + us = timestamp->tv_nsec / 1000; + + if (resize_msg != NULL && resize_msg->len > 0) { + strncpy(p, resize_msg->buf, resize_msg->len); + bytes += resize_msg->len; + p += resize_msg->len; + bufspace -= resize_msg->len; + } + + if (excuse) + r = snprintf(p, bufspace, +"%ld.%06ld Latency %d printout skipped due to %s\n", + sec, us, req->ticket, str); + else + r = snprintf(p, bufspace, "%ld.%06ld Latency %d detected\n", + sec, us, req->ticket); + + if (r < 0) + warn("snprintf() failed"); + else + bytes += r; + + /* These prints could happen concurrently */ + mutex_lock(&print_mtx); + write_or_die(fd_stdout, buffer, bytes); + mutex_unlock(&print_mtx); +} + +static void print_skipmessage(const struct short_msg *resize_msg, + const struct timespec *timestamp, char *buffer, + size_t bufspace, const struct entry *req, + bool excuse) +{ + __print_skipmessage(resize_msg, timestamp, buffer, bufspace, req, + excuse, "random delay"); +} + +static void print_lostmessage(const struct timespec *timestamp, char *buffer, + size_t bufspace, const struct entry *req, + const char *reason) +{ + __print_skipmessage(NULL, timestamp, buffer, bufspace, req, true, + reason); +} + +static void print_tracefile(const struct short_msg *resize_msg, + const struct timespec *timestamp, char *buffer, + size_t bufspace, long slept, + const struct entry *req) +{ + static const int reserve = 256; + char *p = &buffer[0]; + ssize_t bytes = 0; + ssize_t bytes_tot = 0; + long us, sec; + long slept_ms; + int trace_fd; + + /* Save some space for the final string and final null char */ + bufspace = bufspace - reserve - 1; + + if (resize_msg != NULL && resize_msg->len > 0) { + bytes = resize_msg->len; + strncpy(p, resize_msg->buf, bytes); + bytes_tot += bytes; + p += bytes; + bufspace -= bytes; + } + + trace_fd = open(debug_tracefile, O_RDONLY); + + if (trace_fd < 0) { + warn("open() failed on %s", debug_tracefile); + return; + } + + sec = timestamp->tv_sec; + us = timestamp->tv_nsec / 1000; + + if (slept != 0) { + slept_ms = slept / 1000; + bytes = snprintf(p, bufspace, +"%ld.%06ld Latency %d randomly sleep for %ld ms before print\n", + sec, us, req->ticket, slept_ms); + } else { + bytes = snprintf(p, bufspace, + "%ld.%06ld Latency %d immediate print\n", sec, + us, req->ticket); + } + + if (bytes < 0) { + warn("snprintf() failed"); + return; + } + p += bytes; + bufspace -= bytes; + bytes_tot += bytes; + + bytes = snprintf(p, bufspace, +">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> BEGIN <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n" + ); + + if (bytes < 0) { + warn("snprintf() failed"); + return; + } + + p += bytes; + bufspace -= bytes; + bytes_tot += bytes; + + do { + bytes = read(trace_fd, p, bufspace); + if (bytes < 0) { + if (errno == EINTR) + continue; + warn("read() failed on %s", debug_tracefile); + if (unlikely(close(trace_fd) != 0)) + warn("close() failed on %s", debug_tracefile); + return; + } + if (bytes == 0) + break; + p += bytes; + bufspace -= bytes; + bytes_tot += bytes; + } while (true); + + if (unlikely(close(trace_fd) != 0)) + warn("close() failed on %s", debug_tracefile); + + printstate_cnt_dec(); + /* Add the reserve space back to the budget for the final string */ + bufspace += reserve; + + bytes = snprintf(p, bufspace, + ">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> END <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n\n"); + + if (bytes < 0) { + warn("snprintf() failed"); + return; + } + + bytes_tot += bytes; + + /* These prints could happen concurrently */ + mutex_lock(&print_mtx); + write_or_die(fd_stdout, buffer, bytes_tot); + mutex_unlock(&print_mtx); +} + +static char *get_no_opt(const char *opt) +{ + char *no_opt; + int s; + + s = strlen(opt) + strlen(OPT_NO_PREFIX) + 1; + /* We may be called from cleanup_exit() via set_trace_opt() */ + no_opt = malloc_or_die_nocleanup(s); + strcpy(no_opt, OPT_NO_PREFIX); + strcat(no_opt, opt); + return no_opt; +} + +static char *find_next_optstr(const char *allopt, const char **next) +{ + const char *begin; + const char *end; + char *r; + int s = 0; + + if (allopt == NULL) + return NULL; + + for (begin = allopt; *begin != '\0'; begin++) { + if (isgraph(*begin)) + break; + } + + if (*begin == '\0') + return NULL; + + for (end = begin; *end != '\0' && isgraph(*end); end++) + s++; + + r = malloc_or_die_nocleanup(s + 1); + strncpy(r, begin, s); + r[s] = '\0'; + *next = begin + s; + return r; +} + +static bool get_trace_opt(const char *allopt, const char *opt, bool *found) +{ + *found = false; + char *no_opt; + char *str; + const char *next = allopt; + bool rval = false; + + no_opt = get_no_opt(opt); + + do { + str = find_next_optstr(next, &next); + if (str == NULL) + break; + if (!strcmp(str, opt)) { + *found = true; + rval = true; + free(str); + break; + } + if (!strcmp(str, no_opt)) { + *found = true; + rval = false; + free(str); + break; + } + free(str); + } while (true); + free(no_opt); + + return rval; +} + +static int set_trace_opt(const char *opt, bool value) +{ + char *str; + int r; + + if (value) + str = strdup(opt); + else + str = get_no_opt(opt); + + r = tracefs_instance_file_write(NULL, TR_OPTIONS, str); + free(str); + return r; +} + +void save_trace_opts(struct ftrace_state *state) +{ + char *allopt; + int psize; + int i; + + allopt = tracefs_instance_file_read(NULL, TR_OPTIONS, &psize); + if (!allopt) + errx(EXIT_FAILURE, "Failed to read the %s file\n", TR_OPTIONS); + + for (i = 0; i < OPTIDX_NR; i++) + state->opt[i] = get_trace_opt(allopt, optstr[i], + &state->opt_valid[i]); + + free(allopt); +} + +static void write_file(const char *file, const char *cur, const char *new, + enum errhandling h) +{ + int r; + static const char *emsg = "Failed to write to the %s file!"; + + /* Do nothing if we now that the current and new value are equal */ + if (cur && !needs_change(cur, new)) + return; + + r = tracefs_instance_file_write(NULL, file, new); + if (r < 0) { + if (h) { + warnx(emsg, file); + if (h == ERR_CLEANUP) + cleanup_exit(EXIT_FAILURE); + } else + errx(EXIT_FAILURE, emsg, file); + } + if (verbose_ftrace()) { + mutex_lock(&print_mtx); + printf("%s was set to %s\n", file, new); + mutex_unlock(&print_mtx); + } +} + +static void reset_max_latency(void) +{ + write_file(TR_MAXLAT, NULL, "0", ERR_CLEANUP); +} + +static void save_and_disable_tracer(void) +{ + char *orig_th; + char *tracer; + bool need_nop = false; + + mutex_lock(&save_state.mutex); + + save_trace_opts(&save_state); + tracer = read_file(TR_CURRENT, ERR_EXIT); + orig_th = read_file(TR_THRESH, ERR_EXIT); + + if (needs_change(tracer, NOP_TRACER)) { + mutex_lock(&print_mtx); + if (force_tracer) { + printf( + "The %s tracer is already in use but proceeding anyway!\n", + tracer); + } else { + printf( + "The %s tracer is already in use, cowardly bailing out!\n" + "This could indicate that another program or instance is tracing.\n" + "Use the -F [--force] option to disregard the current tracer.\n", tracer); + exit(0); + } + mutex_unlock(&print_mtx); + need_nop = true; + } + + save_state.tracer = tracer; + save_state.thresh = orig_th; + + if (need_nop) + write_file(TR_CURRENT, NULL, NOP_TRACER, ERR_EXIT); + + mutex_unlock(&save_state.mutex); +} + +void set_trace_opts(struct ftrace_state *state, bool *new) +{ + int i; + int r; + + /* + * We only set options if we earlier detected that the option exists in + * the trace_options file and that the wanted setting is different from + * the one we saw in save_and_disable_tracer() + */ + for (i = 0; i < OPTIDX_NR; i++) + if (state->opt_valid[i] && + state->opt[i] != new[i]) { + r = set_trace_opt(optstr[i], new[i]); + if (r < 0) { + warnx("Failed to set the %s option to %s", + optstr[i], bool2str(new[i])); + cleanup_exit(EXIT_FAILURE); + } + if (verbose_ftrace()) { + mutex_lock(&print_mtx); + printf("%s in %s was set to %s\n", optstr[i], + TR_OPTIONS, bool2str(new[i])); + mutex_unlock(&print_mtx); + } + } +} + +static void enable_tracer(void) +{ + mutex_lock(&save_state.mutex); + set_trace_opts(&save_state, use_options); + + write_file(TR_THRESH, save_state.thresh, threshold, ERR_CLEANUP); + write_file(TR_CURRENT, NOP_TRACER, current_tracer, ERR_CLEANUP); + + mutex_unlock(&save_state.mutex); +} + +static void tracing_loop(void) +{ + int ifd = inotify_init(); + int wd; + const ssize_t bufsize = sizeof(inotify_buffer); + const ssize_t istructsize = sizeof(struct inotify_event); + char *buf = &inotify_buffer[0]; + ssize_t nr_read; + char *p; + int modified; + struct inotify_event *event; + struct entry req; + char *buffer; + const size_t bufspace = PRINT_BUFFER_SIZE; + struct timespec timestamp; + + print_priority(); + + buffer = malloc_or_die(bufspace); + + if (ifd < 0) + err(EXIT_FAILURE, "inotify_init() failed!"); + + + if (setup_ftrace) { + /* + * We must disable the tracer before resetting the max_latency + */ + save_and_disable_tracer(); + /* + * We must reset the max_latency before the inotify_add_watch() + * call. + */ + reset_max_latency(); + } + + wd = inotify_add_watch(ifd, debug_maxlat, IN_MODIFY); + if (wd < 0) + err(EXIT_FAILURE, "inotify_add_watch() failed!"); + + if (setup_ftrace) + enable_tracer(); + + signal_blocking(SIG_UNBLOCK); + + while (true) { + modified = 0; + check_signals(); + nr_read = read(ifd, buf, bufsize); + check_signals(); + if (nr_read < 0) { + if (errno == EINTR) + continue; + warn("read() failed on inotify fd!"); + cleanup_exit(EXIT_FAILURE); + } + if (nr_read == bufsize) + warnx("inotify() buffer filled, skipping events"); + if (nr_read < istructsize) { + warnx("read() returned too few bytes on inotify fd"); + cleanup_exit(EXIT_FAILURE); + } + + for (p = buf; p < buf + nr_read;) { + event = (struct inotify_event *) p; + if ((event->mask & IN_MODIFY) != 0) + modified++; + p += istructsize + event->len; + } + while (modified > 0) { + check_signals(); + mutex_lock(&printstate.mutex); + check_signals(); + printstate_next_ticket(&req); + if (printstate_cnt_read() > 0) { + printstate_mark_req_completed(&req); + mutex_unlock(&printstate.mutex); + if (verbose_lostevent()) { + clock_gettime_or_die(CLOCK_MONOTONIC, + ×tamp); + print_lostmessage(×tamp, buffer, + bufspace, &req, + "inotify loop"); + } + break; + } + mutex_unlock(&printstate.mutex); + if (queue_try_to_add_entry(&printqueue, &req) != 0) { + /* These prints could happen concurrently */ + check_signals(); + mutex_lock(&print_mtx); + check_signals(); + write_or_die(fd_stdout, queue_full_warning, + strlen(queue_full_warning)); + mutex_unlock(&print_mtx); + } + modified--; + } + } +} + +static void *do_printloop(void *arg) +{ + const size_t bufspace = PRINT_BUFFER_SIZE; + char *buffer; + long *rseed = (long *) arg; + struct drand48_data drandbuf; + long slept = 0; + struct entry req; + int prob = 0; + struct timespec timestamp; + struct short_msg resize_msg; + + print_priority(); + + if (srand48_r(*rseed, &drandbuf) != 0) { + warn("srand48_r() failed!\n"); + cleanup_exit(EXIT_FAILURE); + } + + buffer = malloc_or_die(bufspace); + + while (true) { + req = queue_wait_for_entry(&printqueue); + clock_gettime_or_die(CLOCK_MONOTONIC, ×tamp); + mutex_lock(&printstate.mutex); + if (prev_req_won_race(&req)) { + printstate_mark_req_completed(&req); + mutex_unlock(&printstate.mutex); + if (verbose_lostevent()) + print_lostmessage(×tamp, buffer, bufspace, + &req, "print loop"); + continue; + } + mutex_unlock(&printstate.mutex); + + /* + * Toss a coin to decide if we want to sleep before printing + * out the backtrace. The reason for this is that opening + * /sys/kernel/tracing/trace will cause a blackout of + * hundreds of ms, where no latencies will be noted by the + * latency tracer. Thus by randomly sleeping we try to avoid + * missing traces systematically due to this. With this option + * we will sometimes get the first latency, some other times + * some of the later ones, in case of closely spaced traces. + */ + if (trace_enable && use_random_sleep) { + slept = 0; + prob = table_get_probability(&req, &resize_msg); + if (!toss_coin(&drandbuf, prob)) + slept = go_to_sleep(&req); + if (slept >= 0) { + /* A print is ongoing */ + printstate_cnt_inc(); + /* + * We will do the printout below so we have to + * mark it as completed while we still have the + * mutex. + */ + mutex_lock(&printstate.mutex); + printstate_mark_req_completed(&req); + mutex_unlock(&printstate.mutex); + } + } + if (trace_enable) { + /* + * slept < 0 means that we detected another + * notification in go_to_sleep() above + */ + if (slept >= 0) + /* + * N.B. printstate_cnt_dec(); will be called + * inside print_tracefile() + */ + print_tracefile(&resize_msg, ×tamp, buffer, + bufspace, slept, &req); + else + print_skipmessage(&resize_msg, ×tamp, + buffer, bufspace, &req, true); + } else { + print_skipmessage(&resize_msg, ×tamp, buffer, + bufspace, &req, false); + } + } + return NULL; +} + +static void start_printthread(void) +{ + unsigned int i; + long *seed; + int ufd; + + ufd = open(DEV_URANDOM, O_RDONLY); + if (nr_threads > MAX_THREADS) { + warnx( +"Number of requested print threads was %d, max number is %d\n", + nr_threads, MAX_THREADS); + nr_threads = MAX_THREADS; + } + for (i = 0; i < nr_threads; i++) { + seed = malloc_or_die(sizeof(*seed)); + if (ufd < 0 || + read(ufd, seed, sizeof(*seed)) != sizeof(*seed)) { + printf( +"Warning! Using trivial random number seed, since %s not available\n", + DEV_URANDOM); + fflush(stdout); + *seed = i; + } + errno = pthread_create(&printthread[i], NULL, do_printloop, + seed); + if (errno) + err(EXIT_FAILURE, "pthread_create()"); + } + if (ufd > 0 && close(ufd) != 0) + warn("close() failed"); +} + +static void show_usage(void) +{ + printf( +"Usage: %s [OPTION]...\n\n" +"Collect closely occurring latencies from %s\n" +"with any of the following tracers: preemptirqsoff, preemptoff, irqsoff, " +"wakeup,\nwakeup_dl, or wakeup_rt.\n\n" + +"The occurrence of a latency is detected by monitoring the file\n" +"%s with inotify.\n\n" + +"The following options are supported:\n\n" + +"-l, --list\t\tList the latency tracers that are supported by the\n" +"\t\t\tcurrently running Linux kernel. If you don't see the\n" +"\t\t\ttracer that you want, you will probably need to\n" +"\t\t\tchange your kernel config and build a new kernel.\n\n" + +"-t, --tracer TR\t\tUse the tracer TR. The default is to use the first\n" +"\t\t\ttracer that is supported by the kernel in the following\n" +"\t\t\torder of precedence:\n\n" +"\t\t\tpreemptirqsoff\n" +"\t\t\tpreemptoff\n" +"\t\t\tirqsoff\n" +"\t\t\twakeup\n" +"\t\t\twakeup_rt\n" +"\t\t\twakeup_dl\n" +"\n" +"\t\t\tIf TR is not on the list above, then a warning will be\n" +"\t\t\tprinted.\n\n" + +"-F, --force\t\tProceed even if another ftrace tracer is active. Without\n" +"\t\t\tthis option, the program will refuse to start tracing if\n" +"\t\t\tany other tracer than the nop tracer is active.\n\n" + +"-s, --threshold TH\tConfigure ftrace to use a threshold of TH microseconds\n" +"\t\t\tfor the tracer. The default is 0, which means that\n" +"\t\t\ttracing_max_latency will be used. tracing_max_latency is\n" +"\t\t\tset to 0 when the program is started and contains the\n" +"\t\t\tmaximum of the latencies that have been encountered.\n\n" + +"-f, --function\t\tEnable the function-trace option in trace_options. With\n" +"\t\t\tthis option, ftrace will trace the functions that are\n" +"\t\t\texecuted during a latency, without it we only get the\n" +"\t\t\tbeginning, end, and backtrace.\n\n" + +"-g, --graph\t\tEnable the display-graph option in trace_option. This\n" +"\t\t\toption causes ftrace to show the graph of how functions\n" +"\t\t\tare calling other functions.\n\n" + +"-c, --policy POL\tRun the program with scheduling policy POL. POL can be\n" +"\t\t\tother, batch, idle, rr or fifo. The default is rr. When\n" +"\t\t\tusing rr or fifo, remember that these policies may cause\n" +"\t\t\tother tasks to experience latencies.\n\n" + +"-p, --priority PRI\tRun the program with priority PRI. The acceptable range\n" +"\t\t\tof PRI depends on the scheduling policy.\n\n" + +"-n, --notrace\t\tIf latency is detected, do not print out the content of\n" +"\t\t\tthe trace file to standard output\n\n" + +"-t, --threads NRTHR\tRun NRTHR threads for printing. Default is %d.\n\n" + +"-r, --random\t\tArbitrarily sleep a certain amount of time, default\n" +"\t\t\t%ld ms, before reading the trace file. The\n" +"\t\t\tprobabilities for sleep are chosen so that the\n" +"\t\t\tprobability of obtaining any of a cluster of closely\n" +"\t\t\toccurring latencies are equal, i.e. we will randomly\n" +"\t\t\tchoose which one we collect from the trace file.\n\n" +"\t\t\tThis option is probably only useful with the irqsoff,\n" +"\t\t\tpreemptoff, and preemptirqsoff tracers.\n\n" + +"-a, --nrlat NRLAT\tFor the purpose of arbitrary delay, assume that there\n" +"\t\t\tare no more than NRLAT clustered latencies. If NRLAT\n" +"\t\t\tlatencies are detected during a run, this value will\n" +"\t\t\tautomatically be increased to NRLAT + 1 and then to\n" +"\t\t\tNRLAT + 2 and so on. The default is %d. This option\n" +"\t\t\timplies -r. We need to know this number in order to\n" +"\t\t\tbe able to calculate the probabilities of sleeping.\n" +"\t\t\tSpecifically, the probabilities of not sleeping, i.e. to\n" +"\t\t\tdo an immediate printout will be:\n\n" +"\t\t\t1/NRLAT 1/(NRLAT - 1) ... 1/3 1/2 1\n\n" +"\t\t\tThe probability of sleeping will be:\n\n" +"\t\t\t1 - P, where P is from the series above\n\n" +"\t\t\tThis descending probability will cause us to choose\n" +"\t\t\tan occurrence at random. Observe that the final\n" +"\t\t\tprobability is 0, it is when we reach this probability\n" +"\t\t\tthat we increase NRLAT automatically. As an example,\n" +"\t\t\twith the default value of 2, the probabilities will be:\n\n" +"\t\t\t1/2 0\n\n" +"\t\t\tThis means, when a latency is detected we will sleep\n" +"\t\t\twith 50%% probability. If we ever detect another latency\n" +"\t\t\tduring the sleep period, then the probability of sleep\n" +"\t\t\twill be 0%% and the table will be expanded to:\n\n" +"\t\t\t1/3 1/2 0\n\n" + +"-v, --verbose\t\tIncrease the verbosity. If this option is given once,\n" +"\t\t\tthen print a message every time that the NRLAT value\n" +"\t\t\tis automatically increased. It also causes a message to\n" +"\t\t\tbe printed when the ftrace settings are changed. If this\n" +"\t\t\toption is given at least twice, then also print a\n" +"\t\t\twarning for lost events.\n\n" + +"-u, --time TIME\t\tArbitrarily sleep for a specified time TIME ms before\n" +"\t\t\tprinting out the trace from the trace file. The default\n" +"\t\t\tis %ld ms. This option implies -r.\n\n" + +"-x, --no-ftrace\t\tDo not configure ftrace. This assume that the user\n" +"\t\t\tconfigures the ftrace files in sysfs such as\n" +"\t\t\t/sys/kernel/tracing/current_tracer or equivalent.\n\n" + +"-i, --tracefile FILE\tUse FILE as trace file. The default is\n" +"\t\t\t%s.\n" +"\t\t\tThis options implies -x\n\n" + +"-m, --max-lat FILE\tUse FILE as tracing_max_latency file. The default is\n" +"\t\t\t%s.\n" +"\t\t\tThis options implies -x\n\n" +, +prg_name, debug_tracefile_dflt, debug_maxlat_dflt, DEFAULT_NR_PRINTER_THREADS, +SLEEP_TIME_MS_DEFAULT, DEFAULT_TABLE_SIZE, SLEEP_TIME_MS_DEFAULT, +debug_tracefile_dflt, debug_maxlat_dflt); +} + +static void find_tracefiles(void) +{ + debug_tracefile_dflt = tracefs_get_tracing_file("trace"); + if (debug_tracefile_dflt == NULL) { + /* This is needed in show_usage() */ + debug_tracefile_dflt = DEBUG_NOFILE; + } + + debug_maxlat_dflt = tracefs_get_tracing_file("tracing_max_latency"); + if (debug_maxlat_dflt == NULL) { + /* This is needed in show_usage() */ + debug_maxlat_dflt = DEBUG_NOFILE; + } + + debug_tracefile = debug_tracefile_dflt; + debug_maxlat = debug_maxlat_dflt; +} + +bool alldigits(const char *s) +{ + for (; *s != '\0'; s++) + if (!isdigit(*s)) + return false; + return true; +} + +void check_alldigits(const char *optarg, const char *argname) +{ + if (!alldigits(optarg)) + errx(EXIT_FAILURE, + "The %s parameter expects a decimal argument\n", argname); +} + +static void scan_arguments(int argc, char *argv[]) +{ + int c; + int i; + int option_idx = 0; + + static struct option long_options[] = { + { "list", no_argument, 0, 'l' }, + { "tracer", required_argument, 0, 't' }, + { "force", no_argument, 0, 'F' }, + { "threshold", required_argument, 0, 's' }, + { "function", no_argument, 0, 'f' }, + { "graph", no_argument, 0, 'g' }, + { "policy", required_argument, 0, 'c' }, + { "priority", required_argument, 0, 'p' }, + { "help", no_argument, 0, 'h' }, + { "notrace", no_argument, 0, 'n' }, + { "random", no_argument, 0, 'r' }, + { "nrlat", required_argument, 0, 'a' }, + { "threads", required_argument, 0, 'e' }, + { "time", required_argument, 0, 'u' }, + { "verbose", no_argument, 0, 'v' }, + { "no-ftrace", no_argument, 0, 'x' }, + { "tracefile", required_argument, 0, 'i' }, + { "max-lat", required_argument, 0, 'm' }, + { 0, 0, 0, 0 } + }; + const struct policy *p; + int max, min; + int value; + bool notracer, valid; + + /* + * We must do this before parsing the arguments because show_usage() + * needs to display these. + */ + find_tracefiles(); + + while (true) { + c = getopt_long(argc, argv, "lt:Fs:fgc:p:hnra:e:u:vxi:m:", + long_options, &option_idx); + if (c == -1) + break; + + switch (c) { + case 'l': + show_available(); + exit(0); + break; + case 't': + current_tracer = strdup(optarg); + if (!is_relevant_tracer(current_tracer)) { + warnx("%s is not a known latency tracer!\n", + current_tracer); + } + valid = tracer_valid(current_tracer, ¬racer); + if (notracer) + errx(EXIT_FAILURE, no_tracer_msg); + if (!valid) + errx(EXIT_FAILURE, +"The tracer %s is not supported by your kernel!\n", current_tracer); + break; + case 'F': + force_tracer = true; + break; + case 's': + check_alldigits(optarg, "-s [--threshold]"); + threshold = strdup(optarg); + break; + case 'f': + use_options[OPTIDX_FUNC_TR] = true; + break; + case 'g': + use_options[OPTIDX_DISP_GR] = true; + break; + case 'c': + p = policy_from_name(optarg); + if (p != NULL) { + sched_policy = p->policy; + sched_policy_set = true; + if (!sched_pri_set) { + sched_pri = p->default_pri; + sched_pri_set = true; + } + } else { + warnx("Unknown scheduling %s\n", optarg); + show_usage(); + exit(0); + } + break; + case 'p': + check_alldigits(optarg, "-p [--priority]"); + sched_pri = atoi(optarg); + sched_pri_set = true; + break; + case 'h': + show_usage(); + exit(0); + break; + case 'n': + trace_enable = false; + use_random_sleep = false; + break; + case 'e': + check_alldigits(optarg, "-e [--threads]"); + value = atoi(optarg); + if (value > 0) + nr_threads = value; + else { + warnx("NRTHR must be > 0\n"); + show_usage(); + exit(0); + } + break; + case 'u': + check_alldigits(optarg, "-u [--time]"); + value = atoi(optarg); + if (value < 0) { + warnx("TIME must be >= 0\n"); + show_usage(); + exit(0); + } + trace_enable = true; + use_random_sleep = true; + sleep_time = value * USEC_PER_MSEC; + break; + case 'v': + verbosity++; + break; + case 'r': + trace_enable = true; + use_random_sleep = true; + break; + case 'a': + check_alldigits(optarg, "-a [--nrlat]"); + value = atoi(optarg); + if (value <= 0) { + warnx("NRLAT must be > 0\n"); + show_usage(); + exit(0); + } + trace_enable = true; + use_random_sleep = true; + table_startsize = value; + break; + case 'x': + setup_ftrace = false; + break; + case 'i': + setup_ftrace = false; + debug_tracefile = strdup(optarg); + break; + case 'm': + setup_ftrace = false; + debug_maxlat = strdup(optarg); + break; + default: + show_usage(); + exit(0); + break; + } + } + + if (setup_ftrace) { + if (!current_tracer) { + current_tracer = find_default_tracer(); + if (!current_tracer) + errx(EXIT_FAILURE, +"No default tracer found and tracer not specified\n"); + } + + if (use_random_sleep && !random_makes_sense(current_tracer)) { + warnx("WARNING: The tracer is %s and random sleep has", + current_tracer); + fprintf(stderr, +"been enabled. Random sleep is intended for the following tracers:\n"); + for (i = 0; random_tracers[i]; i++) + fprintf(stderr, "%s\n", random_tracers[i]); + fprintf(stderr, "\n"); + } + } + + if (debug_tracefile == DEBUG_NOFILE || + debug_maxlat == DEBUG_NOFILE) + errx(EXIT_FAILURE, +"Could not find tracing directory e.g. /sys/kernel/tracing\n"); + + if (!sched_policy_set) { + sched_policy = SCHED_RR; + sched_policy_set = true; + if (!sched_pri_set) { + sched_pri = RT_DEFAULT_PRI; + sched_pri_set = true; + } + } + + max = sched_get_priority_max(sched_policy); + min = sched_get_priority_min(sched_policy); + + if (sched_pri < min) { + printf( +"ATTENTION: Increasing priority to minimum, which is %d\n", min); + sched_pri = min; + } + if (sched_pri > max) { + printf( +"ATTENTION: Reducing priority to maximum, which is %d\n", max); + sched_pri = max; + } +} + +static void show_params(void) +{ + printf( +"\n" +"Running with scheduling policy %s and priority %d. Using %d print threads.\n", + policy_name(sched_policy), sched_pri, nr_threads); + if (trace_enable) { + if (use_random_sleep) { + printf( +"%s will be printed with random delay\n" +"Start size of the probability table:\t\t\t%d\n" +"Print a message when the prob. table changes size:\t%s\n" +"Print a warning when an event has been lost:\t\t%s\n" +"Sleep time is:\t\t\t\t\t\t%ld ms\n", +debug_tracefile, +table_startsize, +bool2str(verbose_sizechange()), +bool2str(verbose_lostevent()), +sleep_time / USEC_PER_MSEC); + } else { + printf("%s will be printed immediately\n", + debug_tracefile); + } + } else { + printf("%s will not be printed\n", + debug_tracefile); + } + if (setup_ftrace) { + printf("Tracer:\t\t\t\t\t\t\t%s\n" + "%s option:\t\t\t\t\t%s\n" + "%s option:\t\t\t\t\t%s\n", + current_tracer, + optstr[OPTIDX_FUNC_TR], + bool2str(use_options[OPTIDX_FUNC_TR]), + optstr[OPTIDX_DISP_GR], + bool2str(use_options[OPTIDX_DISP_GR])); + if (!strcmp(threshold, "0")) + printf("Threshold:\t\t\t\t\t\ttracing_max_latency\n"); + else + printf("Threshold:\t\t\t\t\t\t%s\n", threshold); + } + printf("\n"); +} + +int main(int argc, char *argv[]) +{ + init_save_state(); + signal_blocking(SIG_BLOCK); + setup_sig_handler(); + open_stdout(); + + if (argc >= 1) + prg_name = argv[0]; + else + prg_name = prg_unknown; + + scan_arguments(argc, argv); + show_params(); + + init_printstate(); + init_print_mtx(); + if (use_random_sleep) { + init_probabilities(); + if (verbose_sizechange()) + printf("Initializing probability table to %d\n", + table_startsize); + sleeptable_resize(table_startsize, false, NULL); + } + set_priority(); + init_queue(&printqueue); + start_printthread(); + tracing_loop(); + return 0; +} |