From df9bd7d452dfdcebfc1bdf317c74c3af09cc9719 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 8 Sep 2020 19:34:45 -0700 Subject: [PATCH] helper_thread: Rework the interval timer code Instead of adding the number of milliseconds that have elapsed when a timer fires, add the timer interval. Reduce code duplication by introducing a helper function that verifies whether or not a timer has expired. Signed-off-by: Bart Van Assche --- helper_thread.c | 154 +++++++++++++++++++++++++++++++++--------------- 1 file changed, 105 insertions(+), 49 deletions(-) diff --git a/helper_thread.c b/helper_thread.c index 40f99a5e..f6cdddb8 100644 --- a/helper_thread.c +++ b/helper_thread.c @@ -1,4 +1,5 @@ #include +#include #ifdef CONFIG_VALGRIND_DEV #include #else @@ -11,6 +12,8 @@ #include "steadystate.h" #include "pshared.h" +static int sleep_accuracy_ms; + enum action { A_EXIT = 1, A_RESET = 2, @@ -25,6 +28,13 @@ static struct helper_data { struct fio_sem *startup_sem; } *helper_data; +struct interval_timer { + const char *name; + struct timespec expires; + uint32_t interval_ms; + int (*func)(void); +}; + void helper_thread_destroy(void) { if (!helper_data) @@ -140,6 +150,23 @@ void helper_thread_exit(void) pthread_join(helper_data->thread, NULL); } +/* Resets timers and returns the time in milliseconds until the next event. */ +static int reset_timers(struct interval_timer timer[], int num_timers, + struct timespec *now) +{ + uint32_t msec_to_next_event = INT_MAX; + int i; + + for (i = 0; i < num_timers; ++i) { + timer[i].expires = *now; + timespec_add_msec(&timer[i].expires, timer[i].interval_ms); + msec_to_next_event = min_not_zero(msec_to_next_event, + timer[i].interval_ms); + } + + return msec_to_next_event; +} + /* * Waits for an action from fd during at least timeout_ms. `fd` must be in * non-blocking mode. @@ -172,31 +199,78 @@ static uint8_t wait_for_action(int fd, unsigned int timeout_ms) return action; } -static unsigned int task_helper(struct timespec *last, struct timespec *now, unsigned int period, void do_task()) +/* + * Verify whether or not timer @it has expired. If timer @it has expired, call + * @it->func(). @now is the current time. @msec_to_next_event is an + * input/output parameter that represents the time until the next event. + */ +static int eval_timer(struct interval_timer *it, const struct timespec *now, + unsigned int *msec_to_next_event) { - unsigned int next, since; - - since = mtime_since(last, now); - if (since >= period || period - since < 10) { - do_task(); - timespec_add_msec(last, since); - if (since > period) - next = period - (since - period); - else - next = period; - } else - next = period - since; - - return next; + int64_t delta_ms; + bool expired; + + /* interval == 0 means that the timer is disabled. */ + if (it->interval_ms == 0) + return 0; + + delta_ms = rel_time_since(now, &it->expires); + expired = delta_ms <= sleep_accuracy_ms; + if (expired) { + timespec_add_msec(&it->expires, it->interval_ms); + delta_ms = rel_time_since(now, &it->expires); + if (delta_ms < it->interval_ms - sleep_accuracy_ms || + delta_ms > it->interval_ms + sleep_accuracy_ms) { + dprint(FD_HELPERTHREAD, + "%s: delta = %" PRIi64 " <> %u. Clock jump?\n", + it->name, delta_ms, it->interval_ms); + delta_ms = it->interval_ms; + it->expires = *now; + timespec_add_msec(&it->expires, it->interval_ms); + } + } + *msec_to_next_event = min((unsigned int)delta_ms, *msec_to_next_event); + return expired ? it->func() : 0; } static void *helper_thread_main(void *data) { struct helper_data *hd = data; - unsigned int msec_to_next_event, next_log, next_si = status_interval; - unsigned int next_ss = STEADYSTATE_MSEC; - struct timespec ts, last_du, last_ss, last_si; - int ret = 0; + unsigned int msec_to_next_event, next_log; + struct interval_timer timer[] = { + { + .name = "disk_util", + .interval_ms = DISK_UTIL_MSEC, + .func = update_io_ticks, + }, + { + .name = "status_interval", + .interval_ms = status_interval, + .func = __show_running_run_stats, + }, + { + .name = "steadystate", + .interval_ms = steadystate_enabled ? STEADYSTATE_MSEC : + 0, + .func = steadystate_check, + } + }; + struct timespec ts; + int clk_tck, ret = 0; + +#ifdef _SC_CLK_TCK + clk_tck = sysconf(_SC_CLK_TCK); +#else + /* + * The timer frequence is variable on Windows. Instead of trying to + * query it, use 64 Hz, the clock frequency lower bound. See also + * https://carpediemsystems.co.uk/2019/07/18/windows-system-timer-granularity/. + */ + clk_tck = 64; +#endif + dprint(FD_HELPERTHREAD, "clk_tck = %d\n", clk_tck); + assert(clk_tck > 0); + sleep_accuracy_ms = (1000 + clk_tck - 1) / clk_tck; sk_out_assign(hd->sk_out); @@ -204,16 +278,13 @@ static void *helper_thread_main(void *data) block_signals(); fio_get_mono_time(&ts); - memcpy(&last_du, &ts, sizeof(ts)); - memcpy(&last_ss, &ts, sizeof(ts)); - memcpy(&last_si, &ts, sizeof(ts)); + msec_to_next_event = reset_timers(timer, ARRAY_SIZE(timer), &ts); fio_sem_up(hd->startup_sem); - msec_to_next_event = DISK_UTIL_MSEC; while (!ret && !hd->exit) { - uint64_t since_du; uint8_t action; + int i; action = wait_for_action(hd->pipe[0], msec_to_next_event); if (action == A_EXIT) @@ -221,41 +292,26 @@ static void *helper_thread_main(void *data) fio_get_mono_time(&ts); - if (action == A_RESET) { - last_du = ts; - last_ss = ts; - } + msec_to_next_event = INT_MAX; + + if (action == A_RESET) + msec_to_next_event = reset_timers(timer, + ARRAY_SIZE(timer), &ts); - since_du = mtime_since(&last_du, &ts); - if (since_du >= DISK_UTIL_MSEC || DISK_UTIL_MSEC - since_du < 10) { - ret = update_io_ticks(); - timespec_add_msec(&last_du, DISK_UTIL_MSEC); - msec_to_next_event = DISK_UTIL_MSEC; - if (since_du >= DISK_UTIL_MSEC) - msec_to_next_event -= (since_du - DISK_UTIL_MSEC); - } else - msec_to_next_event = DISK_UTIL_MSEC - since_du; + for (i = 0; i < ARRAY_SIZE(timer); ++i) + ret = eval_timer(&timer[i], &ts, &msec_to_next_event); if (action == A_DO_STAT) __show_running_run_stats(); - if (status_interval) { - next_si = task_helper(&last_si, &ts, status_interval, __show_running_run_stats); - msec_to_next_event = min(next_si, msec_to_next_event); - } - next_log = calc_log_samples(); if (!next_log) next_log = DISK_UTIL_MSEC; - if (steadystate_enabled) { - next_ss = task_helper(&last_ss, &ts, STEADYSTATE_MSEC, steadystate_check); - msec_to_next_event = min(next_ss, msec_to_next_event); - } - msec_to_next_event = min(next_log, msec_to_next_event); - dprint(FD_HELPERTHREAD, "next_si: %u, next_ss: %u, next_log: %u, msec_to_next_event: %u\n", - next_si, next_ss, next_log, msec_to_next_event); + dprint(FD_HELPERTHREAD, + "next_log: %u, msec_to_next_event: %u\n", + next_log, msec_to_next_event); if (!is_backend) print_thread_status(); -- 2.25.1