X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Ftimeval.c;h=d8539892afa57145f6d90d84056f1eb0dc86c010;hb=c2f0373a8248d0c20d2f876d7f3bc61a400d9924;hp=77247e80ac71583c9690522bf7e9153bfdfc7d26;hpb=a457574880b01a30c16e9b92c9ead760631de3c1;p=openvswitch diff --git a/lib/timeval.c b/lib/timeval.c index 77247e80..d8539892 100644 --- a/lib/timeval.c +++ b/lib/timeval.c @@ -18,6 +18,9 @@ #include "timeval.h" #include #include +#if HAVE_EXECINFO_H +#include +#endif #include #include #include @@ -27,7 +30,10 @@ #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" @@ -40,15 +46,7 @@ VLOG_DEFINE_THIS_MODULE(timeval); * to CLOCK_REALTIME. */ static clockid_t monotonic_clock; -/* Controls whether or not calls to clock_gettime() are cached. See - * time_cached() for a detailed explanation. */ -#if defined __x86_64__ && defined __linux__ -static bool cache_time = false; -#else -static bool cache_time = true; -#endif - -/* Has a timer tick occurred? Only relevant if cache_time is true. +/* 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. */ @@ -69,6 +67,19 @@ static bool time_stopped; /* Disables real-time updates, if true. */ /* 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); @@ -81,17 +92,51 @@ 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; + +#ifndef HAVE_EXECINFO_H +#define HAVE_EXECINFO_H 0 + +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 /* 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 (HAVE_EXECINFO_H) { + void *bt[1]; + + backtrace(bt, ARRAY_SIZE(bt)); + } + + memset(traces, 0, sizeof traces); + + if (HAVE_EXECINFO_H && CACHE_TIME) { + unixctl_command_register("backtrace", "", 0, 0, backtrace_cb, NULL); + } + coverage_init(); if (!clock_gettime(CLOCK_MONOTONIC, &monotonic_time)) { @@ -154,15 +199,12 @@ set_up_timer(void) static timer_t timer_id; /* "static" to avoid apparent memory leak. */ struct itimerspec itimer; - if (!cache_time) { + if (!CACHE_TIME) { return; } if (timer_create(monotonic_clock, NULL, &timer_id)) { - VLOG_WARN("timer_create failed (%s), disabling cached timing", - strerror(errno)); - cache_time = false; - return; + VLOG_FATAL("timer_create failed (%s)", strerror(errno)); } itimer.it_interval.tv_sec = 0; @@ -215,7 +257,7 @@ refresh_monotonic(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 + * CACHE_TIME is false, we will always refresh the current time so this * function has no effect. */ void time_refresh(void) @@ -312,14 +354,16 @@ 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; @@ -356,7 +400,7 @@ time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, break; } - if (!blocked && !cache_time) { + if (!blocked && CACHE_TIME) { block_sigalrm(&oldsigs); blocked = true; } @@ -370,34 +414,25 @@ time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when, return retval; } -/* True on systems (particularly x86-64 Linux) where clock_gettime() is - * inexpensive. On these systems, we don't bother caching the current time. - * Instead, we consult clock_gettime() directly when needed. - * - * False on systems where clock_gettime() is relatively expensive. On these - * systems, we cache the current time and set up a periodic SIGALRM to remind - * us to update it. - * - * Also false on systems (e.g. ESX) that don't support setting up timers based - * on a monotonically increasing clock. */ -bool -time_cached(void) -{ - time_init(); - return cache_time; -} - static void sigalrm_handler(int sig_nr OVS_UNUSED) { wall_tick = true; monotonic_tick = true; + + if (HAVE_EXECINFO_H && 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) { + if (!CACHE_TIME || wall_tick) { refresh_wall(); } } @@ -405,7 +440,7 @@ refresh_wall_if_ticked(void) static void refresh_monotonic_if_ticked(void) { - if (!cache_time || monotonic_tick) { + if (!CACHE_TIME || monotonic_tick) { refresh_monotonic(); } } @@ -480,66 +515,40 @@ 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 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) { - static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 3); - - if (!VLOG_DROP_WARN(&rl)) { - 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); - if (rusage.ru_minflt > last_rusage->ru_minflt - || rusage.ru_majflt > last_rusage->ru_majflt) { - VLOG_WARN("faults: %ld minor, %ld major", - rusage.ru_minflt - last_rusage->ru_minflt, - rusage.ru_majflt - last_rusage->ru_majflt); - } - if (rusage.ru_inblock > last_rusage->ru_inblock - || rusage.ru_oublock > last_rusage->ru_oublock) { - VLOG_WARN("disk: %ld reads, %ld writes", - rusage.ru_inblock - last_rusage->ru_inblock, - rusage.ru_oublock - last_rusage->ru_oublock); - } - if (rusage.ru_nvcsw > last_rusage->ru_nvcsw - || rusage.ru_nivcsw > last_rusage->ru_nivcsw) { - VLOG_WARN("context switches: %ld voluntary, %ld involuntary", - rusage.ru_nvcsw - last_rusage->ru_nvcsw, - rusage.ru_nivcsw - last_rusage->ru_nivcsw); - } + long long int interval = time_msec() - last_wakeup; + + if (interval >= 1000) { + const struct rusage *last_rusage = get_recent_rusage(); + struct rusage rusage; + + getrusage(RUSAGE_SELF, &rusage); + 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", + rusage.ru_minflt - last_rusage->ru_minflt, + rusage.ru_majflt - last_rusage->ru_majflt); + } + if (rusage.ru_inblock > last_rusage->ru_inblock + || rusage.ru_oublock > last_rusage->ru_oublock) { + VLOG_WARN("disk: %ld reads, %ld writes", + rusage.ru_inblock - last_rusage->ru_inblock, + rusage.ru_oublock - last_rusage->ru_oublock); + } + if (rusage.ru_nvcsw > last_rusage->ru_nvcsw + || rusage.ru_nivcsw > last_rusage->ru_nivcsw) { + VLOG_WARN("context switches: %ld voluntary, %ld involuntary", + rusage.ru_nvcsw - last_rusage->ru_nvcsw, + rusage.ru_nivcsw - last_rusage->ru_nivcsw); } coverage_log(); } - - /* 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; - } } /* CPU usage tracking. */ @@ -593,6 +602,89 @@ 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 (HAVE_EXECINFO_H && 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. */ @@ -632,6 +724,19 @@ timeval_warp_cb(struct unixctl_conn *conn, 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; + + assert(HAVE_EXECINFO_H && CACHE_TIME); + format_backtraces(&ds, 0); + unixctl_command_reply(conn, ds_cstr(&ds)); + ds_destroy(&ds); +} + void timeval_dummy_register(void) {