blob: e6be24026c9a714240c0f66a224b784c0969f454 [file] [log] [blame]
/*
* Task management functions.
*
* Copyright 2000-2009 Willy Tarreau <w@1wt.eu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <string.h>
#include <common/config.h>
#include <common/memory.h>
#include <common/mini-clist.h>
#include <common/standard.h>
#include <common/time.h>
#include <eb32sctree.h>
#include <eb32tree.h>
#include <proto/fd.h>
#include <proto/freq_ctr.h>
#include <proto/proxy.h>
#include <proto/stream.h>
#include <proto/task.h>
DECLARE_POOL(pool_head_task, "task", sizeof(struct task));
DECLARE_POOL(pool_head_tasklet, "tasklet", sizeof(struct tasklet));
/* This is the memory pool containing all the signal structs. These
* struct are used to store each required signal between two tasks.
*/
DECLARE_POOL(pool_head_notification, "notification", sizeof(struct notification));
unsigned int nb_tasks = 0;
volatile unsigned long global_tasks_mask = 0; /* Mask of threads with tasks in the global runqueue */
unsigned int tasks_run_queue = 0;
unsigned int tasks_run_queue_cur = 0; /* copy of the run queue size */
unsigned int nb_tasks_cur = 0; /* copy of the tasks count */
unsigned int niced_tasks = 0; /* number of niced tasks in the run queue */
THREAD_LOCAL struct task_per_thread *sched = &task_per_thread[0]; /* scheduler context for the current thread */
__decl_aligned_spinlock(rq_lock); /* spin lock related to run queue */
__decl_aligned_rwlock(wq_lock); /* RW lock related to the wait queue */
#ifdef USE_THREAD
struct eb_root timers; /* sorted timers tree, global */
struct eb_root rqueue; /* tree constituting the run queue */
int global_rqueue_size; /* Number of element sin the global runqueue */
#endif
static unsigned int rqueue_ticks; /* insertion count */
struct task_per_thread task_per_thread[MAX_THREADS];
/* Puts the task <t> in run queue at a position depending on t->nice. <t> is
* returned. The nice value assigns boosts in 32th of the run queue size. A
* nice value of -1024 sets the task to -tasks_run_queue*32, while a nice value
* of 1024 sets the task to tasks_run_queue*32. The state flags are cleared, so
* the caller will have to set its flags after this call.
* The task must not already be in the run queue. If unsure, use the safer
* task_wakeup() function.
*/
void __task_wakeup(struct task *t, struct eb_root *root)
{
#ifdef USE_THREAD
if (root == &rqueue) {
HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
}
#endif
/* Make sure if the task isn't in the runqueue, nobody inserts it
* in the meanwhile.
*/
_HA_ATOMIC_ADD(&tasks_run_queue, 1);
#ifdef USE_THREAD
if (root == &rqueue) {
global_tasks_mask |= t->thread_mask;
__ha_barrier_store();
}
#endif
t->rq.key = _HA_ATOMIC_ADD(&rqueue_ticks, 1);
if (likely(t->nice)) {
int offset;
_HA_ATOMIC_ADD(&niced_tasks, 1);
offset = t->nice * (int)global.tune.runqueue_depth;
t->rq.key += offset;
}
if (task_profiling_mask & tid_bit)
t->call_date = now_mono_time();
eb32sc_insert(root, &t->rq, t->thread_mask);
#ifdef USE_THREAD
if (root == &rqueue) {
global_rqueue_size++;
_HA_ATOMIC_OR(&t->state, TASK_GLOBAL);
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
} else
#endif
{
int nb = ((void *)root - (void *)&task_per_thread[0].rqueue) / sizeof(task_per_thread[0]);
task_per_thread[nb].rqueue_size++;
}
#ifdef USE_THREAD
/* If all threads that are supposed to handle this task are sleeping,
* wake one.
*/
if ((((t->thread_mask & all_threads_mask) & sleeping_thread_mask) ==
(t->thread_mask & all_threads_mask))) {
unsigned long m = (t->thread_mask & all_threads_mask) &~ tid_bit;
m = (m & (m - 1)) ^ m; // keep lowest bit set
_HA_ATOMIC_AND(&sleeping_thread_mask, ~m);
wake_thread(my_ffsl(m) - 1);
}
#endif
return;
}
/*
* __task_queue()
*
* Inserts a task into wait queue <wq> at the position given by its expiration
* date. It does not matter if the task was already in the wait queue or not,
* as it will be unlinked. The task must not have an infinite expiration timer.
* Last, tasks must not be queued further than the end of the tree, which is
* between <now_ms> and <now_ms> + 2^31 ms (now+24days in 32bit).
*
* This function should not be used directly, it is meant to be called by the
* inline version of task_queue() which performs a few cheap preliminary tests
* before deciding to call __task_queue(). Moreover this function doesn't care
* at all about locking so the caller must be careful when deciding whether to
* lock or not around this call.
*/
void __task_queue(struct task *task, struct eb_root *wq)
{
if (likely(task_in_wq(task)))
__task_unlink_wq(task);
/* the task is not in the queue now */
task->wq.key = task->expire;
#ifdef DEBUG_CHECK_INVALID_EXPIRATION_DATES
if (tick_is_lt(task->wq.key, now_ms))
/* we're queuing too far away or in the past (most likely) */
return;
#endif
eb32_insert(wq, &task->wq);
}
/*
* Extract all expired timers from the timer queue, and wakes up all
* associated tasks.
*/
void wake_expired_tasks()
{
struct task_per_thread * const tt = sched; // thread's tasks
struct task *task;
struct eb32_node *eb;
__decl_hathreads(int key);
while (1) {
lookup_next_local:
eb = eb32_lookup_ge(&tt->timers, now_ms - TIMER_LOOK_BACK);
if (!eb) {
/* we might have reached the end of the tree, typically because
* <now_ms> is in the first half and we're first scanning the last
* half. Let's loop back to the beginning of the tree now.
*/
eb = eb32_first(&tt->timers);
if (likely(!eb))
break;
}
if (tick_is_lt(now_ms, eb->key))
break;
/* timer looks expired, detach it from the queue */
task = eb32_entry(eb, struct task, wq);
__task_unlink_wq(task);
/* It is possible that this task was left at an earlier place in the
* tree because a recent call to task_queue() has not moved it. This
* happens when the new expiration date is later than the old one.
* Since it is very unlikely that we reach a timeout anyway, it's a
* lot cheaper to proceed like this because we almost never update
* the tree. We may also find disabled expiration dates there. Since
* we have detached the task from the tree, we simply call task_queue
* to take care of this. Note that we might occasionally requeue it at
* the same place, before <eb>, so we have to check if this happens,
* and adjust <eb>, otherwise we may skip it which is not what we want.
* We may also not requeue the task (and not point eb at it) if its
* expiration time is not set.
*/
if (!tick_is_expired(task->expire, now_ms)) {
if (tick_isset(task->expire))
__task_queue(task, &tt->timers);
goto lookup_next_local;
}
task_wakeup(task, TASK_WOKEN_TIMER);
}
#ifdef USE_THREAD
if (eb_is_empty(&timers))
goto leave;
HA_RWLOCK_RDLOCK(TASK_WQ_LOCK, &wq_lock);
eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
if (!eb) {
eb = eb32_first(&timers);
if (likely(!eb)) {
HA_RWLOCK_RDUNLOCK(TASK_WQ_LOCK, &wq_lock);
goto leave;
}
}
key = eb->key;
HA_RWLOCK_RDUNLOCK(TASK_WQ_LOCK, &wq_lock);
if (tick_is_lt(now_ms, key))
goto leave;
/* There's really something of interest here, let's visit the queue */
while (1) {
HA_RWLOCK_WRLOCK(TASK_WQ_LOCK, &wq_lock);
lookup_next:
eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
if (!eb) {
/* we might have reached the end of the tree, typically because
* <now_ms> is in the first half and we're first scanning the last
* half. Let's loop back to the beginning of the tree now.
*/
eb = eb32_first(&timers);
if (likely(!eb))
break;
}
if (tick_is_lt(now_ms, eb->key))
break;
/* timer looks expired, detach it from the queue */
task = eb32_entry(eb, struct task, wq);
__task_unlink_wq(task);
/* It is possible that this task was left at an earlier place in the
* tree because a recent call to task_queue() has not moved it. This
* happens when the new expiration date is later than the old one.
* Since it is very unlikely that we reach a timeout anyway, it's a
* lot cheaper to proceed like this because we almost never update
* the tree. We may also find disabled expiration dates there. Since
* we have detached the task from the tree, we simply call task_queue
* to take care of this. Note that we might occasionally requeue it at
* the same place, before <eb>, so we have to check if this happens,
* and adjust <eb>, otherwise we may skip it which is not what we want.
* We may also not requeue the task (and not point eb at it) if its
* expiration time is not set.
*/
if (!tick_is_expired(task->expire, now_ms)) {
if (tick_isset(task->expire))
__task_queue(task, &timers);
goto lookup_next;
}
task_wakeup(task, TASK_WOKEN_TIMER);
HA_RWLOCK_WRUNLOCK(TASK_WQ_LOCK, &wq_lock);
}
HA_RWLOCK_WRUNLOCK(TASK_WQ_LOCK, &wq_lock);
#endif
leave:
return;
}
/* Checks the next timer for the current thread by looking into its own timer
* list and the global one. It may return TICK_ETERNITY if no timer is present.
* Note that the next timer might very well be slighly in the past.
*/
int next_timer_expiry()
{
struct task_per_thread * const tt = sched; // thread's tasks
struct eb32_node *eb;
int ret = TICK_ETERNITY;
__decl_hathreads(int key);
/* first check in the thread-local timers */
eb = eb32_lookup_ge(&tt->timers, now_ms - TIMER_LOOK_BACK);
if (!eb) {
/* we might have reached the end of the tree, typically because
* <now_ms> is in the first half and we're first scanning the last
* half. Let's loop back to the beginning of the tree now.
*/
eb = eb32_first(&tt->timers);
}
if (eb)
ret = eb->key;
#ifdef USE_THREAD
if (!eb_is_empty(&timers)) {
HA_RWLOCK_RDLOCK(TASK_WQ_LOCK, &wq_lock);
eb = eb32_lookup_ge(&timers, now_ms - TIMER_LOOK_BACK);
if (!eb)
eb = eb32_first(&timers);
if (eb)
key = eb->key;
HA_RWLOCK_RDUNLOCK(TASK_WQ_LOCK, &wq_lock);
if (eb)
ret = tick_first(ret, key);
}
#endif
return ret;
}
/* Walks over tasklet list <list> and run at most <max> of them. Returns
* the number of entries effectively processed (tasks and tasklets merged).
* The count of tasks in the list for the current thread is adjusted.
*/
int run_tasks_from_list(struct list *list, int max)
{
struct task *(*process)(struct task *t, void *ctx, unsigned short state);
struct task *t;
unsigned short state;
void *ctx;
int done = 0;
while (done < max && !LIST_ISEMPTY(list)) {
t = (struct task *)LIST_ELEM(list->n, struct tasklet *, list);
state = (t->state & (TASK_SHARED_WQ|TASK_SELF_WAKING));
ti->flags &= ~TI_FL_STUCK; // this thread is still running
activity[tid].ctxsw++;
ctx = t->context;
process = t->process;
t->calls++;
sched->current = t;
if (TASK_IS_TASKLET(t)) {
state = _HA_ATOMIC_XCHG(&t->state, state);
__ha_barrier_atomic_store();
__tasklet_remove_from_tasklet_list((struct tasklet *)t);
process(t, ctx, state);
done++;
sched->current = NULL;
__ha_barrier_store();
continue;
}
state = _HA_ATOMIC_XCHG(&t->state, state | TASK_RUNNING);
__ha_barrier_atomic_store();
__tasklet_remove_from_tasklet_list((struct tasklet *)t);
/* OK then this is a regular task */
task_per_thread[tid].task_list_size--;
if (unlikely(t->call_date)) {
uint64_t now_ns = now_mono_time();
t->lat_time += now_ns - t->call_date;
t->call_date = now_ns;
}
__ha_barrier_store();
if (likely(process == process_stream))
t = process_stream(t, ctx, state);
else if (process != NULL)
t = process(t, ctx, state);
else {
__task_free(t);
sched->current = NULL;
__ha_barrier_store();
/* We don't want max_processed to be decremented if
* we're just freeing a destroyed task, we should only
* do so if we really ran a task.
*/
continue;
}
sched->current = NULL;
__ha_barrier_store();
/* If there is a pending state we have to wake up the task
* immediately, else we defer it into wait queue
*/
if (t != NULL) {
if (unlikely(t->call_date)) {
t->cpu_time += now_mono_time() - t->call_date;
t->call_date = 0;
}
state = _HA_ATOMIC_AND(&t->state, ~TASK_RUNNING);
if (state & TASK_WOKEN_ANY)
task_wakeup(t, 0);
else
task_queue(t);
}
done++;
}
return done;
}
/* The run queue is chronologically sorted in a tree. An insertion counter is
* used to assign a position to each task. This counter may be combined with
* other variables (eg: nice value) to set the final position in the tree. The
* counter may wrap without a problem, of course. We then limit the number of
* tasks processed to 200 in any case, so that general latency remains low and
* so that task positions have a chance to be considered. The function scans
* both the global and local run queues and picks the most urgent task between
* the two. We need to grab the global runqueue lock to touch it so it's taken
* on the very first access to the global run queue and is released as soon as
* it reaches the end.
*
* The function adjusts <next> if a new event is closer.
*/
void process_runnable_tasks()
{
struct task_per_thread * const tt = sched;
struct eb32sc_node *lrq = NULL; // next local run queue entry
struct eb32sc_node *grq = NULL; // next global run queue entry
struct task *t;
int max_processed, done;
struct mt_list *tmp_list;
ti->flags &= ~TI_FL_STUCK; // this thread is still running
if (!thread_has_tasks()) {
activity[tid].empty_rq++;
return;
}
/* Merge the list of tasklets waken up by other threads to the
* main list.
*/
tmp_list = MT_LIST_BEHEAD(&sched->shared_tasklet_list);
if (tmp_list)
LIST_SPLICE_END_DETACHED(&sched->tasklets[TL_URGENT], (struct list *)tmp_list);
tasks_run_queue_cur = tasks_run_queue; /* keep a copy for reporting */
nb_tasks_cur = nb_tasks;
max_processed = global.tune.runqueue_depth;
if (likely(niced_tasks))
max_processed = (max_processed + 3) / 4;
/* run up to max_processed/3 urgent tasklets */
done = run_tasks_from_list(&tt->tasklets[TL_URGENT], (max_processed + 2) / 3);
max_processed -= done;
/* pick up to max_processed/2 (~=3/4*(max_processed-done)) regular tasks from prio-ordered run queues */
/* Note: the grq lock is always held when grq is not null */
while (tt->task_list_size < (3 * max_processed + 3) / 4) {
if ((global_tasks_mask & tid_bit) && !grq) {
#ifdef USE_THREAD
HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
grq = eb32sc_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
if (unlikely(!grq)) {
grq = eb32sc_first(&rqueue, tid_bit);
if (!grq) {
global_tasks_mask &= ~tid_bit;
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
}
}
#endif
}
/* If a global task is available for this thread, it's in grq
* now and the global RQ is locked.
*/
if (!lrq) {
lrq = eb32sc_lookup_ge(&tt->rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
if (unlikely(!lrq))
lrq = eb32sc_first(&tt->rqueue, tid_bit);
}
if (!lrq && !grq)
break;
if (likely(!grq || (lrq && (int)(lrq->key - grq->key) <= 0))) {
t = eb32sc_entry(lrq, struct task, rq);
lrq = eb32sc_next(lrq, tid_bit);
__task_unlink_rq(t);
}
#ifdef USE_THREAD
else {
t = eb32sc_entry(grq, struct task, rq);
grq = eb32sc_next(grq, tid_bit);
__task_unlink_rq(t);
if (unlikely(!grq)) {
grq = eb32sc_first(&rqueue, tid_bit);
if (!grq) {
global_tasks_mask &= ~tid_bit;
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
}
}
}
#endif
/* Make sure the entry doesn't appear to be in a list */
LIST_INIT(&((struct tasklet *)t)->list);
/* And add it to the local task list */
tasklet_insert_into_tasklet_list(&tt->tasklets[TL_NORMAL], (struct tasklet *)t);
tt->task_list_size++;
activity[tid].tasksw++;
}
/* release the rqueue lock */
if (grq) {
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
grq = NULL;
}
/* run between 0.4*max_processed and max_processed/2 regular tasks */
done = run_tasks_from_list(&tt->tasklets[TL_NORMAL], (3 * max_processed + 3) / 4);
max_processed -= done;
/* run between max_processed/4 and max_processed bulk tasklets */
done = run_tasks_from_list(&tt->tasklets[TL_BULK], max_processed);
max_processed -= done;
if (!LIST_ISEMPTY(&sched->tasklets[TL_URGENT]) |
!LIST_ISEMPTY(&sched->tasklets[TL_NORMAL]) |
!LIST_ISEMPTY(&sched->tasklets[TL_BULK]))
activity[tid].long_rq++;
}
/* create a work list array for <nbthread> threads, using tasks made of
* function <fct>. The context passed to the function will be the pointer to
* the thread's work list, which will contain a copy of argument <arg>. The
* wake up reason will be TASK_WOKEN_OTHER. The pointer to the work_list array
* is returned on success, otherwise NULL on failure.
*/
struct work_list *work_list_create(int nbthread,
struct task *(*fct)(struct task *, void *, unsigned short),
void *arg)
{
struct work_list *wl;
int i;
wl = calloc(nbthread, sizeof(*wl));
if (!wl)
goto fail;
for (i = 0; i < nbthread; i++) {
MT_LIST_INIT(&wl[i].head);
wl[i].task = task_new(1UL << i);
if (!wl[i].task)
goto fail;
wl[i].task->process = fct;
wl[i].task->context = &wl[i];
wl[i].arg = arg;
}
return wl;
fail:
work_list_destroy(wl, nbthread);
return NULL;
}
/* destroy work list <work> */
void work_list_destroy(struct work_list *work, int nbthread)
{
int t;
if (!work)
return;
for (t = 0; t < nbthread; t++)
task_destroy(work[t].task);
free(work);
}
/*
* Delete every tasks before running the master polling loop
*/
void mworker_cleantasks()
{
struct task *t;
int i;
struct eb32_node *tmp_wq = NULL;
struct eb32sc_node *tmp_rq = NULL;
#ifdef USE_THREAD
/* cleanup the global run queue */
tmp_rq = eb32sc_first(&rqueue, MAX_THREADS_MASK);
while (tmp_rq) {
t = eb32sc_entry(tmp_rq, struct task, rq);
tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
task_destroy(t);
}
/* cleanup the timers queue */
tmp_wq = eb32_first(&timers);
while (tmp_wq) {
t = eb32_entry(tmp_wq, struct task, wq);
tmp_wq = eb32_next(tmp_wq);
task_destroy(t);
}
#endif
/* clean the per thread run queue */
for (i = 0; i < global.nbthread; i++) {
tmp_rq = eb32sc_first(&task_per_thread[i].rqueue, MAX_THREADS_MASK);
while (tmp_rq) {
t = eb32sc_entry(tmp_rq, struct task, rq);
tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
task_destroy(t);
}
/* cleanup the per thread timers queue */
tmp_wq = eb32_first(&task_per_thread[i].timers);
while (tmp_wq) {
t = eb32_entry(tmp_wq, struct task, wq);
tmp_wq = eb32_next(tmp_wq);
task_destroy(t);
}
}
}
/* perform minimal intializations */
static void init_task()
{
int i;
#ifdef USE_THREAD
memset(&timers, 0, sizeof(timers));
memset(&rqueue, 0, sizeof(rqueue));
#endif
memset(&task_per_thread, 0, sizeof(task_per_thread));
for (i = 0; i < MAX_THREADS; i++) {
LIST_INIT(&task_per_thread[i].tasklets[TL_URGENT]);
LIST_INIT(&task_per_thread[i].tasklets[TL_NORMAL]);
LIST_INIT(&task_per_thread[i].tasklets[TL_BULK]);
MT_LIST_INIT(&task_per_thread[i].shared_tasklet_list);
}
}
INITCALL0(STG_PREPARE, init_task);
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/