X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Ftimeval.c;h=faf8e7bc8be277b1d3dac0b80d74822ac1f36cb3;hb=6b900de4efd368be88ef3db88b1eff8f835a7cf7;hp=d2b7508af654babc79ea786abb0016deb38fdffe;hpb=a19b84f4a6f0716ff641750c2aa0785c0e6e59b5;p=sliver-openvswitch.git diff --git a/lib/timeval.c b/lib/timeval.c index d2b7508af..faf8e7bc8 100644 --- a/lib/timeval.c +++ b/lib/timeval.c @@ -18,6 +18,7 @@ #include "timeval.h" #include #include +#include #include #include #include @@ -30,66 +31,45 @@ #include "fatal-signal.h" #include "hash.h" #include "hmap.h" +#include "ovs-thread.h" #include "signals.h" #include "unixctl.h" #include "util.h" #include "vlog.h" -/* backtrace() from is really useful, but it is not signal safe - * everywhere, such as on x86-64. */ -#if HAVE_BACKTRACE && !defined __x86_64__ -# define USE_BACKTRACE 1 -# include -#else -# define USE_BACKTRACE 0 -#endif - VLOG_DEFINE_THIS_MODULE(timeval); -/* The clock to use for measuring time intervals. This is CLOCK_MONOTONIC by - * preference, but on systems that don't have a monotonic clock we fall back - * to CLOCK_REALTIME. */ -static clockid_t monotonic_clock; +struct clock { + clockid_t id; /* CLOCK_MONOTONIC or CLOCK_REALTIME. */ + struct ovs_rwlock rwlock; /* Mutual exclusion for 'cache'. */ -/* Has a timer tick occurred? Only relevant if CACHE_TIME is true. - * - * We initialize these to true to force time_init() to get called on the first - * call to time_msec() or another function that queries the current time. */ -static volatile sig_atomic_t wall_tick = true; -static volatile sig_atomic_t monotonic_tick = true; + /* Features for use by unit tests. Protected by 'rwlock'. */ + struct timespec warp; /* Offset added for unit tests. */ + bool stopped; /* Disables real-time updates if true. */ + + /* Relevant only if CACHE_TIME is true. */ + volatile sig_atomic_t tick; /* Has the timer ticked? Set by signal. */ + struct timespec cache; /* Last time read from kernel. */ +}; -/* The current time, as of the last refresh. */ -static struct timespec wall_time; -static struct timespec monotonic_time; +/* Our clocks. */ +static struct clock monotonic_clock; /* CLOCK_MONOTONIC, if available. */ +static struct clock wall_clock; /* CLOCK_REALTIME. */ /* The monotonic time at which the time module was initialized. */ static long long int boot_time; -/* features for use by unit tests. */ -static struct timespec warp_offset; /* Offset added to monotonic_time. */ -static bool time_stopped; /* Disables real-time updates, if true. */ - -/* Time in milliseconds at which to die with SIGALRM (if not LLONG_MAX). */ +/* Monotonic time in milliseconds at which to die with SIGALRM (if not + * LLONG_MAX). */ static long long int deadline = LLONG_MAX; -struct trace { - void *backtrace[32]; /* Populated by backtrace(). */ - size_t n_frames; /* Number of frames in 'backtrace'. */ - - /* format_backtraces() helper data. */ - struct hmap_node node; - size_t count; -}; - -#define MAX_TRACES 50 -static struct trace traces[MAX_TRACES]; -static size_t trace_head = 0; +/* Monotonic time, in milliseconds, at which the last call to time_poll() woke + * up. */ +DEFINE_STATIC_PER_THREAD_DATA(long long int, last_wakeup, 0); static void set_up_timer(void); static void set_up_signal(int flags); static void sigalrm_handler(int); -static void refresh_wall_if_ticked(void); -static void refresh_monotonic_if_ticked(void); static void block_sigalrm(sigset_t *); static void unblock_sigalrm(const sigset_t *); static void log_poll_interval(long long int last_wakeup); @@ -97,62 +77,39 @@ static struct rusage *get_recent_rusage(void); static void refresh_rusage(void); static void timespec_add(struct timespec *sum, const struct timespec *a, const struct timespec *b); -static unixctl_cb_func backtrace_cb; -#if !USE_BACKTRACE -static int -backtrace(void **buffer OVS_UNUSED, int size OVS_UNUSED) -{ - NOT_REACHED(); -} - -static char ** -backtrace_symbols(void *const *buffer OVS_UNUSED, int size OVS_UNUSED) +static void +init_clock(struct clock *c, clockid_t id) { - NOT_REACHED(); + memset(c, 0, sizeof *c); + c->id = id; + ovs_rwlock_init(&c->rwlock); + xclock_gettime(c->id, &c->cache); } -#endif /* !USE_BACKTRACE */ -/* Initializes the timetracking module, if not already initialized. */ static void -time_init(void) +do_init_time(void) { - static bool inited; - - if (inited) { - return; - } - inited = true; - - /* The implementation of backtrace() in glibc does some one time - * initialization which is not signal safe. This can cause deadlocks if - * run from the signal handler. As a workaround, force the initialization - * to happen here. */ - if (USE_BACKTRACE) { - void *bt[1]; - - backtrace(bt, ARRAY_SIZE(bt)); - } - - memset(traces, 0, sizeof traces); - - if (USE_BACKTRACE && CACHE_TIME) { - unixctl_command_register("backtrace", "", 0, 0, backtrace_cb, NULL); - } + struct timespec ts; coverage_init(); - if (!clock_gettime(CLOCK_MONOTONIC, &monotonic_time)) { - monotonic_clock = CLOCK_MONOTONIC; - } else { - monotonic_clock = CLOCK_REALTIME; - VLOG_DBG("monotonic timer not available"); - } + init_clock(&monotonic_clock, (!clock_gettime(CLOCK_MONOTONIC, &ts) + ? CLOCK_MONOTONIC + : CLOCK_REALTIME)); + init_clock(&wall_clock, CLOCK_REALTIME); + boot_time = timespec_to_msec(&monotonic_clock.cache); set_up_signal(SA_RESTART); set_up_timer(); +} - boot_time = time_msec(); +/* Initializes the timetracking module, if not already initialized. */ +static void +time_init(void) +{ + static pthread_once_t once = PTHREAD_ONCE_INIT; + pthread_once(&once, do_init_time); } static void @@ -167,35 +124,6 @@ set_up_signal(int flags) xsigaction(SIGALRM, &sa, NULL); } -/* Remove SA_RESTART from the flags for SIGALRM, so that any system call that - * is interrupted by the periodic timer interrupt will return EINTR instead of - * continuing after the signal handler returns. - * - * time_disable_restart() and time_enable_restart() may be usefully wrapped - * around function calls that might otherwise block forever unless interrupted - * by a signal, e.g.: - * - * time_disable_restart(); - * fcntl(fd, F_SETLKW, &lock); - * time_enable_restart(); - */ -void -time_disable_restart(void) -{ - time_init(); - set_up_signal(0); -} - -/* Add SA_RESTART to the flags for SIGALRM, so that any system call that - * is interrupted by the periodic timer interrupt will continue after the - * signal handler returns instead of returning EINTR. */ -void -time_enable_restart(void) -{ - time_init(); - set_up_signal(SA_RESTART); -} - static void set_up_timer(void) { @@ -206,8 +134,8 @@ set_up_timer(void) return; } - if (timer_create(monotonic_clock, NULL, &timer_id)) { - VLOG_FATAL("timer_create failed (%s)", strerror(errno)); + if (timer_create(monotonic_clock.id, NULL, &timer_id)) { + VLOG_FATAL("timer_create failed (%s)", ovs_strerror(errno)); } itimer.it_interval.tv_sec = 0; @@ -215,7 +143,7 @@ set_up_timer(void) itimer.it_value = itimer.it_interval; if (timer_settime(timer_id, 0, &itimer, NULL)) { - VLOG_FATAL("timer_settime failed (%s)", strerror(errno)); + VLOG_FATAL("timer_settime failed (%s)", ovs_strerror(errno)); } } @@ -227,95 +155,107 @@ set_up_timer(void) void time_postfork(void) { + assert_single_threaded(); time_init(); set_up_timer(); } -static void -refresh_wall(void) +/* Forces a refresh of the current time from the kernel. It is not usually + * necessary to call this function, since the time will be refreshed + * automatically at least every TIME_UPDATE_INTERVAL milliseconds. If + * CACHE_TIME is false, we will always refresh the current time so this + * function has no effect. */ +void +time_refresh(void) { - time_init(); - clock_gettime(CLOCK_REALTIME, &wall_time); - wall_tick = false; + monotonic_clock.tick = wall_clock.tick = true; } static void -refresh_monotonic(void) +time_timespec__(struct clock *c, struct timespec *ts) { time_init(); - - if (!time_stopped) { - if (monotonic_clock == CLOCK_MONOTONIC) { - clock_gettime(monotonic_clock, &monotonic_time); - } else { - refresh_wall_if_ticked(); - monotonic_time = wall_time; + for (;;) { + /* Use the cached time by preference, but fall through if there's been + * a clock tick. */ + ovs_rwlock_rdlock(&c->rwlock); + if (c->stopped || !c->tick) { + timespec_add(ts, &c->cache, &c->warp); + ovs_rwlock_unlock(&c->rwlock); + return; } - timespec_add(&monotonic_time, &monotonic_time, &warp_offset); + ovs_rwlock_unlock(&c->rwlock); - monotonic_tick = false; + /* Refresh the cache. */ + ovs_rwlock_wrlock(&c->rwlock); + if (c->tick) { + c->tick = false; + xclock_gettime(c->id, &c->cache); + } + ovs_rwlock_unlock(&c->rwlock); } } -/* Forces a refresh of the current time from the kernel. It is not usually - * necessary to call this function, since the time will be refreshed - * automatically at least every TIME_UPDATE_INTERVAL milliseconds. If - * CACHE_TIME is false, we will always refresh the current time so this - * function has no effect. */ +/* Stores a monotonic timer, accurate within TIME_UPDATE_INTERVAL ms, into + * '*ts'. */ void -time_refresh(void) +time_timespec(struct timespec *ts) +{ + time_timespec__(&monotonic_clock, ts); +} + +/* Stores the current time, accurate within TIME_UPDATE_INTERVAL ms, into + * '*ts'. */ +void +time_wall_timespec(struct timespec *ts) +{ + time_timespec__(&wall_clock, ts); +} + +static time_t +time_sec__(struct clock *c) { - wall_tick = monotonic_tick = true; + struct timespec ts; + + time_timespec__(c, &ts); + return ts.tv_sec; } /* Returns a monotonic timer, in seconds. */ time_t time_now(void) { - refresh_monotonic_if_ticked(); - return monotonic_time.tv_sec; + return time_sec__(&monotonic_clock); } /* Returns the current time, in seconds. */ time_t time_wall(void) { - refresh_wall_if_ticked(); - return wall_time.tv_sec; + return time_sec__(&wall_clock); +} + +static long long int +time_msec__(struct clock *c) +{ + struct timespec ts; + + time_timespec__(c, &ts); + return timespec_to_msec(&ts); } /* Returns a monotonic timer, in ms (within TIME_UPDATE_INTERVAL ms). */ long long int time_msec(void) { - refresh_monotonic_if_ticked(); - return timespec_to_msec(&monotonic_time); + return time_msec__(&monotonic_clock); } /* Returns the current time, in ms (within TIME_UPDATE_INTERVAL ms). */ long long int time_wall_msec(void) { - refresh_wall_if_ticked(); - return timespec_to_msec(&wall_time); -} - -/* Stores a monotonic timer, accurate within TIME_UPDATE_INTERVAL ms, into - * '*ts'. */ -void -time_timespec(struct timespec *ts) -{ - refresh_monotonic_if_ticked(); - *ts = monotonic_time; -} - -/* Stores the current time, accurate within TIME_UPDATE_INTERVAL ms, into - * '*ts'. */ -void -time_wall_timespec(struct timespec *ts) -{ - refresh_wall_if_ticked(); - *ts = wall_time; + return time_msec__(&wall_clock); } /* Configures the program to die with SIGALRM 'secs' seconds from now, if @@ -326,6 +266,7 @@ time_alarm(unsigned int secs) long long int now; long long int msecs; + assert_single_threaded(); time_init(); time_refresh(); @@ -352,15 +293,16 @@ int time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, int *elapsed) { - static long long int last_wakeup = 0; + long long int *last_wakeup = last_wakeup_get(); long long int start; sigset_t oldsigs; bool blocked; int retval; + time_init(); time_refresh(); - if (last_wakeup) { - log_poll_interval(last_wakeup); + if (*last_wakeup) { + log_poll_interval(*last_wakeup); } coverage_clear(); start = time_msec(); @@ -406,41 +348,16 @@ time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, if (blocked) { unblock_sigalrm(&oldsigs); } - last_wakeup = time_msec(); + *last_wakeup = time_msec(); refresh_rusage(); - *elapsed = last_wakeup - start; + *elapsed = *last_wakeup - start; return retval; } static void sigalrm_handler(int sig_nr OVS_UNUSED) { - wall_tick = true; - monotonic_tick = true; - - if (USE_BACKTRACE && CACHE_TIME) { - struct trace *trace = &traces[trace_head]; - - trace->n_frames = backtrace(trace->backtrace, - ARRAY_SIZE(trace->backtrace)); - trace_head = (trace_head + 1) % MAX_TRACES; - } -} - -static void -refresh_wall_if_ticked(void) -{ - if (!CACHE_TIME || wall_tick) { - refresh_wall(); - } -} - -static void -refresh_monotonic_if_ticked(void) -{ - if (!CACHE_TIME || monotonic_tick) { - refresh_monotonic(); - } + monotonic_clock.tick = wall_clock.tick = true; } static void @@ -471,7 +388,7 @@ timeval_to_msec(const struct timeval *tv) } /* Returns the monotonic time at which the "time" module was initialized, in - * milliseconds(). */ + * milliseconds. */ long long int time_boot_msec(void) { @@ -483,7 +400,17 @@ void xgettimeofday(struct timeval *tv) { if (gettimeofday(tv, NULL) == -1) { - VLOG_FATAL("gettimeofday failed (%s)", strerror(errno)); + VLOG_FATAL("gettimeofday failed (%s)", ovs_strerror(errno)); + } +} + +void +xclock_gettime(clock_t id, struct timespec *ts) +{ + if (clock_gettime(id, ts) == -1) { + /* It seems like a bad idea to try to use vlog here because it is + * likely to try to check the current time. */ + ovs_abort(errno, "xclock_gettime() failed"); } } @@ -515,7 +442,9 @@ log_poll_interval(long long int last_wakeup) { long long int interval = time_msec() - last_wakeup; - if (interval >= 1000 && !warp_offset.tv_sec && !warp_offset.tv_nsec) { + if (interval >= 1000 + && !monotonic_clock.warp.tv_sec + && !monotonic_clock.warp.tv_nsec) { const struct rusage *last_rusage = get_recent_rusage(); struct rusage rusage; @@ -556,37 +485,66 @@ struct cpu_usage { unsigned long long int cpu; /* Total user+system CPU usage when sampled. */ }; -static struct rusage recent_rusage; -static struct cpu_usage older = { LLONG_MIN, 0 }; -static struct cpu_usage newer = { LLONG_MIN, 0 }; -static int cpu_usage = -1; +struct cpu_tracker { + struct cpu_usage older; + struct cpu_usage newer; + int cpu_usage; + + struct rusage recent_rusage; +}; +DEFINE_PER_THREAD_MALLOCED_DATA(struct cpu_tracker *, cpu_tracker_var); + +static struct cpu_tracker * +get_cpu_tracker(void) +{ + struct cpu_tracker *t = cpu_tracker_var_get(); + if (!t) { + t = xzalloc(sizeof *t); + t->older.when = LLONG_MIN; + t->newer.when = LLONG_MIN; + cpu_tracker_var_set_unsafe(t); + } + return t; +} static struct rusage * get_recent_rusage(void) { - return &recent_rusage; + return &get_cpu_tracker()->recent_rusage; +} + +static int +getrusage_thread(struct rusage *rusage OVS_UNUSED) +{ +#ifdef RUSAGE_THREAD + return getrusage(RUSAGE_THREAD, rusage); +#else + errno = EINVAL; + return -1; +#endif } static void refresh_rusage(void) { - long long int now; + struct cpu_tracker *t = get_cpu_tracker(); + struct rusage *recent_rusage = &t->recent_rusage; - now = time_msec(); - getrusage(RUSAGE_SELF, &recent_rusage); - - if (now >= newer.when + 3 * 1000) { - older = newer; - newer.when = now; - newer.cpu = (timeval_to_msec(&recent_rusage.ru_utime) + - timeval_to_msec(&recent_rusage.ru_stime)); - - if (older.when != LLONG_MIN && newer.cpu > older.cpu) { - unsigned int dividend = newer.cpu - older.cpu; - unsigned int divisor = (newer.when - older.when) / 100; - cpu_usage = divisor > 0 ? dividend / divisor : -1; - } else { - cpu_usage = -1; + if (!getrusage_thread(recent_rusage)) { + long long int now = time_msec(); + if (now >= t->newer.when + 3 * 1000) { + t->older = t->newer; + t->newer.when = now; + t->newer.cpu = (timeval_to_msec(&recent_rusage->ru_utime) + + timeval_to_msec(&recent_rusage->ru_stime)); + + if (t->older.when != LLONG_MIN && t->newer.cpu > t->older.cpu) { + unsigned int dividend = t->newer.cpu - t->older.cpu; + unsigned int divisor = (t->newer.when - t->older.when) / 100; + t->cpu_usage = divisor > 0 ? dividend / divisor : -1; + } else { + t->cpu_usage = -1; + } } } } @@ -598,90 +556,7 @@ refresh_rusage(void) int get_cpu_usage(void) { - return cpu_usage; -} - -static uint32_t -hash_trace(struct trace *trace) -{ - return hash_bytes(trace->backtrace, - trace->n_frames * sizeof *trace->backtrace, 0); -} - -static struct trace * -trace_map_lookup(struct hmap *trace_map, struct trace *key) -{ - struct trace *value; - - HMAP_FOR_EACH_WITH_HASH (value, node, hash_trace(key), trace_map) { - if (key->n_frames == value->n_frames - && !memcmp(key->backtrace, value->backtrace, - key->n_frames * sizeof *key->backtrace)) { - return value; - } - } - return NULL; -} - -/* Appends a string to 'ds' representing backtraces recorded at regular - * intervals in the recent past. This information can be used to get a sense - * of what the process has been spending the majority of time doing. Will - * ommit any backtraces which have not occurred at least 'min_count' times. */ -void -format_backtraces(struct ds *ds, size_t min_count) -{ - time_init(); - - if (USE_BACKTRACE && CACHE_TIME) { - struct hmap trace_map = HMAP_INITIALIZER(&trace_map); - struct trace *trace, *next; - sigset_t oldsigs; - size_t i; - - block_sigalrm(&oldsigs); - - for (i = 0; i < MAX_TRACES; i++) { - struct trace *trace = &traces[i]; - struct trace *map_trace; - - if (!trace->n_frames) { - continue; - } - - map_trace = trace_map_lookup(&trace_map, trace); - if (map_trace) { - map_trace->count++; - } else { - hmap_insert(&trace_map, &trace->node, hash_trace(trace)); - trace->count = 1; - } - } - - HMAP_FOR_EACH_SAFE (trace, next, node, &trace_map) { - char **frame_strs; - size_t j; - - hmap_remove(&trace_map, &trace->node); - - if (trace->count < min_count) { - continue; - } - - frame_strs = backtrace_symbols(trace->backtrace, trace->n_frames); - - ds_put_format(ds, "Count %zu\n", trace->count); - for (j = 0; j < trace->n_frames; j++) { - ds_put_format(ds, "%s\n", frame_strs[j]); - } - ds_put_cstr(ds, "\n"); - - free(frame_strs); - } - hmap_destroy(&trace_map); - - ds_chomp(ds, '\n'); - unblock_sigalrm(&oldsigs); - } + return get_cpu_tracker()->cpu_usage; } /* Unixctl interface. */ @@ -693,7 +568,10 @@ timeval_stop_cb(struct unixctl_conn *conn, int argc OVS_UNUSED, const char *argv[] OVS_UNUSED, void *aux OVS_UNUSED) { - time_stopped = true; + ovs_rwlock_wrlock(&monotonic_clock.rwlock); + monotonic_clock.stopped = true; + ovs_rwlock_unlock(&monotonic_clock.rwlock); + unixctl_command_reply(conn, NULL); } @@ -717,22 +595,12 @@ timeval_warp_cb(struct unixctl_conn *conn, ts.tv_sec = msecs / 1000; ts.tv_nsec = (msecs % 1000) * 1000 * 1000; - timespec_add(&warp_offset, &warp_offset, &ts); - timespec_add(&monotonic_time, &monotonic_time, &ts); - unixctl_command_reply(conn, "warped"); -} -static void -backtrace_cb(struct unixctl_conn *conn, - int argc OVS_UNUSED, const char *argv[] OVS_UNUSED, - void *aux OVS_UNUSED) -{ - struct ds ds = DS_EMPTY_INITIALIZER; + ovs_rwlock_wrlock(&monotonic_clock.rwlock); + timespec_add(&monotonic_clock.warp, &monotonic_clock.warp, &ts); + ovs_rwlock_unlock(&monotonic_clock.rwlock); - ovs_assert(USE_BACKTRACE && CACHE_TIME); - format_backtraces(&ds, 0); - unixctl_command_reply(conn, ds_cstr(&ds)); - ds_destroy(&ds); + unixctl_command_reply(conn, "warped"); } void