X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=sched.c;h=d42e149801e4a7ecabd4f96cc1f79802eb7a4ff1;hp=4c94c423a548a8ddec894f1fcef4b28b14a6a003;hb=6bcd10bc4ada11a04bc2b7425afe5a8855592cd2;hpb=85094cd802bdb606d4e2bf7ed66dec51db2a0953 diff --git a/sched.c b/sched.c index 4c94c423..d42e1498 100644 --- a/sched.c +++ b/sched.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2006-2011 Andre Noll + * Copyright (C) 2006-2013 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ @@ -8,7 +8,6 @@ #include #include -#include #include "para.h" #include "ipc.h" @@ -50,16 +49,12 @@ static inline bool timeout_is_zero(struct sched *s) static void sched_preselect(struct sched *s) { struct task *t, *tmp; + list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) { - if (t->error < 0) { - unregister_task(t); - continue; - } - if (!t->pre_select) - continue; - t->pre_select(s, t); - if (timeout_is_zero(s)) - break; + if (t->notification != 0) + sched_min_delay(s); + if (t->pre_select) + t->pre_select(s, t); } } @@ -67,14 +62,14 @@ static void sched_preselect(struct sched *s) static inline void call_post_select(struct sched *s, struct task *t) { #ifndef SCHED_DEBUG - t->post_select(s, t); + t->error = t->post_select(s, t); #else struct timeval t1, t2, diff; unsigned long pst; - gettimeofday(&t1, NULL); - t->post_select(s, t); - gettimeofday(&t2, NULL); + clock_get_realtime(&t1); + t->error = t->post_select(s, t); + clock_get_realtime(&t2); tv_diff(&t1, &t2, &diff); pst = tv2ms(&diff); if (pst > 50) @@ -91,16 +86,9 @@ static void sched_post_select(struct sched *s) if (t->error >= 0) call_post_select(s, t); // PARA_INFO_LOG("%s: %d\n", t->status, t->ret); + t->notification = 0; if (t->error >= 0) continue; - /* - * We have to check whether the list is empty because the call - * to ->post_select() might have called sched_shutdown(). In - * this case t has been unregistered already, so we must not - * unregister it again. - */ - if (list_empty(&s->post_select_list)) - return; unregister_task(t); } } @@ -131,30 +119,23 @@ again: FD_ZERO(&s->wfds); s->select_timeout = s->default_timeout; s->max_fileno = -1; - gettimeofday(now, NULL); + clock_get_realtime(now); sched_preselect(s); - if (list_empty(&s->pre_select_list) && list_empty(&s->post_select_list)) - return 0; - if (!timeout_is_zero(s)) { - ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, - &s->select_timeout); - if (ret < 0) - return ret; - if (ret == 0) { - /* - * APUE: Be careful not to check the descriptor sets on return - * unless the return value is greater than zero. The return - * state of the descriptor sets is implementation dependent if - * either a signal is caught or the timer expires. - */ - FD_ZERO(&s->rfds); - FD_ZERO(&s->wfds); - } - gettimeofday(now, NULL); - } else { + ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, + &s->select_timeout); + if (ret < 0) + return ret; + if (ret == 0) { + /* + * APUE: Be careful not to check the descriptor sets on return + * unless the return value is greater than zero. The return + * state of the descriptor sets is implementation dependent if + * either a signal is caught or the timer expires. + */ FD_ZERO(&s->rfds); FD_ZERO(&s->wfds); } + clock_get_realtime(now); sched_post_select(s); if (list_empty(&s->pre_select_list) && list_empty(&s->post_select_list)) return 0; @@ -175,6 +156,7 @@ again: void register_task(struct sched *s, struct task *t) { PARA_INFO_LOG("registering %s (%p)\n", t->status, t); + t->notification = 0; if (!s->pre_select_list.next) INIT_LIST_HEAD(&s->pre_select_list); if (!s->post_select_list.next) @@ -189,30 +171,11 @@ void register_task(struct sched *s, struct task *t) } } -/** - * Unregister all tasks. - * - * This will cause \a schedule() to return immediately because both the - * \a pre_select_list and the \a post_select_list are empty. This function - * must be called from the post_select (rather than the pre_select) method. - */ -void sched_shutdown(struct sched *s) -{ - struct task *t, *tmp; - - list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) { - t->error = -E_SCHED_SHUTDOWN; - unregister_task(t); - } - list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) { - t->error = -E_SCHED_SHUTDOWN; - unregister_task(t); - } -} - /** * Get the list of all registered tasks. * + * \param s The scheduler instance to get the task list from. + * * \return The task list. * * Each entry of the list contains an identifier which is simply a hex number. @@ -241,6 +204,69 @@ char *get_task_list(struct sched *s) return msg; } +/** + * Set the notification value of a task. + * + * \param t The task to notify. + * \param err A positive error code. + * + * Tasks which honor notifications are supposed to call \ref + * task_get_notification() in their post_select function and act on the + * returned notification value. + * + * If the scheduler detects during its pre_select loop that at least one task + * has been notified, the loop terminates, and the post_select methods of all + * taks are immediately called again. + * + * The notification for a task is reset after the call to its post_select + * method. + * + * \sa \ref task_get_notification(). + */ +void task_notify(struct task *t, int err) +{ + assert(err > 0); + if (t->notification == -err) /* ignore subsequent notifications */ + return; + PARA_INFO_LOG("notifying task %s: %s\n", t->status, para_strerror(err)); + t->notification = -err; +} + +/** + * Return the notification value of a task. + * + * \param t The task to get the notification value from. + * + * \return The notification value. If this is negative, the task has been + * notified by another task. Tasks are supposed to check for notifications by + * calling this function from their post_select method. + * + * \sa \ref task_notify(). + */ +int task_get_notification(struct task *t) +{ + return t->notification; +} + +/** + * Set the notification value of all tasks of a scheduler instance. + * + * \param s The scheduler instance whose tasks should be notified. + * \param err A positive error code. + * + * This simply iterates over all existing tasks of \a s and sets each + * task's notification value to \p -err. + */ +void task_notify_all(struct sched *s, int err) +{ + struct task *t; + + list_for_each_entry(t, &s->pre_select_list, pre_select_node) + task_notify(t, err); + list_for_each_entry(t, &s->post_select_list, post_select_node) + task_notify(t, err); +} + /** * Set the select timeout to the minimal possible value. *