X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Ftimeval.c;h=6e415147e4047b3e83cf8d06cdbadb0398a7f018;hb=b40dcae74fb2c1e58d48a38b5da178a78f9bf8a6;hp=c8c02bdc425746648998d74df27a3677e466eae3;hpb=6197af6e4b9890f43380e0a0159886ba3275c75c;p=sliver-openvswitch.git diff --git a/lib/timeval.c b/lib/timeval.c index c8c02bdc4..6e415147e 100644 --- a/lib/timeval.c +++ b/lib/timeval.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks. + * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -16,7 +16,6 @@ #include #include "timeval.h" -#include #include #include #include @@ -27,12 +26,24 @@ #include #include "coverage.h" #include "dummy.h" +#include "dynamic-string.h" #include "fatal-signal.h" +#include "hash.h" +#include "hmap.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_EXECINFO_H && !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 @@ -40,7 +51,7 @@ VLOG_DEFINE_THIS_MODULE(timeval); * to CLOCK_REALTIME. */ static clockid_t monotonic_clock; -/* Has a timer tick occurred? +/* 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. */ @@ -51,18 +62,34 @@ static volatile sig_atomic_t monotonic_tick = true; static struct timespec wall_time; static struct timespec monotonic_time; -/* Fixed monotonic time offset, for use by unit tests. */ -static struct timespec warp_offset; +/* 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 at which to die with SIGALRM (if not TIME_MIN). */ -static time_t deadline = TIME_MIN; +/* 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; 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 time_t time_add(time_t, time_t); static void block_sigalrm(sigset_t *); static void unblock_sigalrm(const sigset_t *); static void log_poll_interval(long long int last_wakeup); @@ -70,20 +97,49 @@ 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; -/* Initializes the timetracking module. - * - * It is not necessary to call this function directly, because other time - * functions will call it automatically, but it doesn't hurt. */ +#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) +{ + NOT_REACHED(); +} +#endif /* !USE_BACKTRACE */ + +/* Initializes the timetracking module, if not already initialized. */ static void time_init(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); + } + coverage_init(); if (!clock_gettime(CLOCK_MONOTONIC, &monotonic_time)) { @@ -95,6 +151,8 @@ time_init(void) set_up_signal(SA_RESTART); set_up_timer(); + + boot_time = time_msec(); } static void @@ -144,6 +202,10 @@ set_up_timer(void) static timer_t timer_id; /* "static" to avoid apparent memory leak. */ struct itimerspec itimer; + if (!CACHE_TIME) { + return; + } + if (timer_create(monotonic_clock, NULL, &timer_id)) { VLOG_FATAL("timer_create failed (%s)", strerror(errno)); } @@ -182,20 +244,24 @@ refresh_monotonic(void) { time_init(); - if (monotonic_clock == CLOCK_MONOTONIC) { - clock_gettime(monotonic_clock, &monotonic_time); - } else { - refresh_wall_if_ticked(); - monotonic_time = wall_time; - } - timespec_add(&monotonic_time, &monotonic_time, &warp_offset); + if (!time_stopped) { + if (monotonic_clock == CLOCK_MONOTONIC) { + clock_gettime(monotonic_clock, &monotonic_time); + } else { + refresh_wall_if_ticked(); + monotonic_time = wall_time; + } + timespec_add(&monotonic_time, &monotonic_time, &warp_offset); - monotonic_tick = false; + monotonic_tick = false; + } } /* 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. */ + * 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) { @@ -210,17 +276,6 @@ time_now(void) return monotonic_time.tv_sec; } -/* Same as time_now() except does not write to static variables, for use in - * signal handlers. */ -static time_t -time_now_sig(void) -{ - struct timespec cur_time; - - clock_gettime(monotonic_clock, &cur_time); - return cur_time.tv_sec; -} - /* Returns the current time, in seconds. */ time_t time_wall(void) @@ -268,11 +323,19 @@ time_wall_timespec(struct timespec *ts) void time_alarm(unsigned int secs) { + long long int now; + long long int msecs; + sigset_t oldsigs; time_init(); + time_refresh(); + + now = time_msec(); + msecs = secs * 1000LL; + block_sigalrm(&oldsigs); - deadline = secs ? time_add(time_now(), secs) : TIME_MIN; + deadline = now < LLONG_MAX - msecs ? now + msecs : LLONG_MAX; unblock_sigalrm(&oldsigs); } @@ -294,17 +357,22 @@ int time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, int *elapsed) { - static long long int last_wakeup; + static long long int last_wakeup = 0; long long int start; sigset_t oldsigs; bool blocked; int retval; time_refresh(); - log_poll_interval(last_wakeup); + if (last_wakeup) { + log_poll_interval(last_wakeup); + } coverage_clear(); start = time_msec(); blocked = false; + + timeout_when = MIN(timeout_when, deadline); + for (;;) { long long int now = time_msec(); int time_left; @@ -321,12 +389,21 @@ time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, if (retval < 0) { retval = -errno; } + time_refresh(); + if (deadline <= time_msec()) { + fatal_signal_handler(SIGALRM); + if (retval < 0) { + retval = 0; + } + break; + } + if (retval != -EINTR) { break; } - if (!blocked && deadline == TIME_MIN) { + if (!blocked && CACHE_TIME) { block_sigalrm(&oldsigs); blocked = true; } @@ -340,29 +417,25 @@ time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, return retval; } -/* Returns the sum of 'a' and 'b', with saturation on overflow or underflow. */ -static time_t -time_add(time_t a, time_t b) -{ - return (a >= 0 - ? (b > TIME_MAX - a ? TIME_MAX : a + b) - : (b < TIME_MIN - a ? TIME_MIN : a + b)); -} - static void -sigalrm_handler(int sig_nr) +sigalrm_handler(int sig_nr OVS_UNUSED) { wall_tick = true; monotonic_tick = true; - if (deadline != TIME_MIN && time_now_sig() > deadline) { - fatal_signal_handler(sig_nr); + + 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 (wall_tick) { + if (!CACHE_TIME || wall_tick) { refresh_wall(); } } @@ -370,7 +443,7 @@ refresh_wall_if_ticked(void) static void refresh_monotonic_if_ticked(void) { - if (monotonic_tick) { + if (!CACHE_TIME || monotonic_tick) { refresh_monotonic(); } } @@ -402,6 +475,15 @@ timeval_to_msec(const struct timeval *tv) return (long long int) tv->tv_sec * 1000 + tv->tv_usec / 1000; } +/* Returns the monotonic time at which the "time" module was initialized, in + * milliseconds(). */ +long long int +time_boot_msec(void) +{ + time_init(); + return boot_time; +} + void xgettimeofday(struct timeval *tv) { @@ -436,32 +518,20 @@ timespec_add(struct timespec *sum, static void log_poll_interval(long long int last_wakeup) { - static unsigned int mean_interval; /* In 16ths of a millisecond. */ - static unsigned int n_samples; + long long int interval = time_msec() - last_wakeup; - long long int now; - unsigned int interval; /* In 16ths of a millisecond. */ - - /* Compute interval from last wakeup to now in 16ths of a millisecond, - * capped at 10 seconds (16000 in this unit). */ - now = time_msec(); - interval = MIN(10000, now - last_wakeup) << 4; - - /* Warn if we took too much time between polls: at least 50 ms and at least - * 8X the mean interval. */ - if (n_samples > 10 && interval > mean_interval * 8 && interval > 50 * 16) { + if (interval >= 1000 && !warp_offset.tv_sec && !warp_offset.tv_nsec) { const struct rusage *last_rusage = get_recent_rusage(); struct rusage rusage; getrusage(RUSAGE_SELF, &rusage); - VLOG_WARN("%lld ms poll interval (%lld ms user, %lld ms system) " - "is over %u times the weighted mean interval %u ms " - "(%u samples)", - now - last_wakeup, - timeval_diff_msec(&rusage.ru_utime, &last_rusage->ru_utime), - timeval_diff_msec(&rusage.ru_stime, &last_rusage->ru_stime), - interval / mean_interval, - (mean_interval + 8) / 16, n_samples); + VLOG_WARN("Unreasonably long %lldms poll interval" + " (%lldms user, %lldms system)", + interval, + timeval_diff_msec(&rusage.ru_utime, + &last_rusage->ru_utime), + timeval_diff_msec(&rusage.ru_stime, + &last_rusage->ru_stime)); if (rusage.ru_minflt > last_rusage->ru_minflt || rusage.ru_majflt > last_rusage->ru_majflt) { VLOG_WARN("faults: %ld minor, %ld major", @@ -480,20 +550,7 @@ log_poll_interval(long long int last_wakeup) rusage.ru_nvcsw - last_rusage->ru_nvcsw, rusage.ru_nivcsw - last_rusage->ru_nivcsw); } - - /* Care should be taken in the value chosen for logging. Depending - * on the configuration, syslog can write changes synchronously, - * which can cause the coverage messages to take longer to log - * than the processing delay that triggered it. */ - coverage_log(VLL_INFO, true); - } - - /* Update exponentially weighted moving average. With these parameters, a - * given value decays to 1% of its value in about 100 time steps. */ - if (n_samples++) { - mean_interval = (mean_interval * 122 + interval * 6 + 64) / 128; - } else { - mean_interval = interval; + coverage_log(); } } @@ -548,9 +605,108 @@ 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); + } +} /* Unixctl interface. */ +/* "time/stop" stops the monotonic time returned by e.g. time_msec() from + * advancing, except due to later calls to "time/warp". */ +static void +timeval_stop_cb(struct unixctl_conn *conn, + int argc OVS_UNUSED, const char *argv[] OVS_UNUSED, + void *aux OVS_UNUSED) +{ + time_stopped = true; + unixctl_command_reply(conn, NULL); +} + +/* "time/warp MSECS" advances the current monotonic time by the specified + * number of milliseconds. Unless "time/stop" has also been executed, the + * monotonic clock continues to tick forward at the normal rate afterward. + * + * Does not affect wall clock readings. */ static void timeval_warp_cb(struct unixctl_conn *conn, int argc OVS_UNUSED, const char *argv[], void *aux OVS_UNUSED) @@ -560,19 +716,34 @@ timeval_warp_cb(struct unixctl_conn *conn, msecs = atoi(argv[1]); if (msecs <= 0) { - unixctl_command_reply(conn, 501, "invalid MSECS"); + unixctl_command_reply_error(conn, "invalid MSECS"); return; } ts.tv_sec = msecs / 1000; ts.tv_nsec = (msecs % 1000) * 1000 * 1000; timespec_add(&warp_offset, &warp_offset, &ts); - unixctl_command_reply(conn, 200, "warped"); + 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_assert(USE_BACKTRACE && CACHE_TIME); + format_backtraces(&ds, 0); + unixctl_command_reply(conn, ds_cstr(&ds)); + ds_destroy(&ds); } void timeval_dummy_register(void) { + unixctl_command_register("time/stop", "", 0, 0, timeval_stop_cb, NULL); unixctl_command_register("time/warp", "MSECS", 1, 1, timeval_warp_cb, NULL); }