blob: 779dbf5d8890006adc416c09670e1d668971eaff [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/proxy.h>
#include <proto/stream.h>
#include <proto/task.h>
#include <proto/fd.h>
struct pool_head *pool_head_task;
struct pool_head *pool_head_tasklet;
/* This is the memory pool containing all the signal structs. These
* struct are used to store each required signal between two tasks.
*/
struct pool_head *pool_head_notification;
unsigned int nb_tasks = 0;
volatile unsigned long active_tasks_mask = 0; /* Mask of threads with active tasks */
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 *curr_task = NULL; /* task currently running or NULL */
THREAD_LOCAL struct eb32sc_node *rq_next = NULL; /* Next task to be potentially run */
__decl_hathreads(HA_SPINLOCK_T __attribute__((aligned(64))) rq_lock); /* spin lock related to run queue */
__decl_hathreads(HA_SPINLOCK_T __attribute__((aligned(64))) wq_lock); /* spin lock related to 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)
{
void *expected = NULL;
int *rq_size;
unsigned long __maybe_unused old_active_mask;
#ifdef USE_THREAD
if (root == &rqueue) {
rq_size = &global_rqueue_size;
HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
} else
#endif
{
int nb = ((void *)root - (void *)&task_per_thread[0].rqueue) / sizeof(task_per_thread[0]);
rq_size = &task_per_thread[nb].rqueue_size;
}
/* Make sure if the task isn't in the runqueue, nobody inserts it
* in the meanwhile.
*/
redo:
if (unlikely(!HA_ATOMIC_CAS(&t->rq.node.leaf_p, &expected, (void *)0x1))) {
#ifdef USE_THREAD
if (root == &rqueue)
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
#endif
return;
}
/* There's a small race condition, when running a task, the thread
* first sets TASK_RUNNING, and then unlink the task.
* If an another thread calls task_wakeup() for the same task,
* it may set t->state before TASK_RUNNING was set, and then try
* to set t->rq.nod.leaf_p after it was unlinked.
* To make sure it is not a problem, we check if TASK_RUNNING is set
* again. If it is, we unset t->rq.node.leaf_p.
* We then check for TASK_RUNNING a third time. If it is still there,
* then we can give up, the task will be re-queued later if it needs
* to be. If it's not there, and there is still something in t->state,
* then we have to requeue.
*/
if (((volatile unsigned short)(t->state)) & TASK_RUNNING) {
unsigned short state;
t->rq.node.leaf_p = NULL;
__ha_barrier_store();
state = (volatile unsigned short)(t->state);
if (unlikely(state != 0 && !(state & TASK_RUNNING)))
goto redo;
#ifdef USE_THREAD
if (root == &rqueue)
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
#endif
return;
}
HA_ATOMIC_ADD(&tasks_run_queue, 1);
#ifdef USE_THREAD
if (root == &rqueue) {
HA_ATOMIC_OR(&global_tasks_mask, t->thread_mask);
__ha_barrier_store();
}
#endif
old_active_mask = active_tasks_mask;
HA_ATOMIC_OR(&active_tasks_mask, t->thread_mask);
t->rq.key = HA_ATOMIC_ADD(&rqueue_ticks, 1);
if (likely(t->nice)) {
int offset;
HA_ATOMIC_ADD(&niced_tasks, 1);
if (likely(t->nice > 0))
offset = (unsigned)((*rq_size * (unsigned int)t->nice) / 32U);
else
offset = -(unsigned)((*rq_size * (unsigned int)-t->nice) / 32U);
t->rq.key += offset;
}
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)) &&
!(t->thread_mask & old_active_mask))
wake_thread(my_ffsl((t->thread_mask & all_threads_mask) &~ tid_bit) - 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. Returns the date of next event (or eternity).
*/
int wake_expired_tasks()
{
struct task *task;
struct eb32_node *eb;
int ret = TICK_ETERNITY;
while (1) {
lookup_next_local:
eb = eb32_lookup_ge(&task_per_thread[tid].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(&task_per_thread[tid].timers);
if (likely(!eb))
break;
}
if (tick_is_lt(now_ms, eb->key)) {
/* timer not expired yet, revisit it later */
ret = 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, &task_per_thread[tid].timers);
goto lookup_next_local;
}
task_wakeup(task, TASK_WOKEN_TIMER);
}
#ifdef USE_THREAD
while (1) {
HA_SPIN_LOCK(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)) {
/* timer not expired yet, revisit it later */
ret = tick_first(ret, 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_SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
}
HA_SPIN_UNLOCK(TASK_WQ_LOCK, &wq_lock);
#endif
return ret;
}
/* 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 adjusts <next> if a new event is closer.
*/
void process_runnable_tasks()
{
struct task *t;
int max_processed;
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(global.nbthread > 1)) {
HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
if (!(active_tasks_mask & tid_bit)) {
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
activity[tid].empty_rq++;
return;
}
#ifdef USE_THREAD
/* Get some elements from the global run queue and put it in the
* local run queue. To try to keep a bit of fairness, just get as
* much elements from the global list as to have a bigger local queue
* than the average.
*/
rq_next = eb32sc_lookup_ge(&rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
while ((task_per_thread[tid].task_list_size + task_per_thread[tid].rqueue_size) * global.nbthread <= tasks_run_queue) {
if (unlikely(!rq_next)) {
/* either we just started or we reached the end
* of the tree, typically because <rqueue_ticks>
* is in the first half and we're first scanning
* the last half. Let's loop back to the beginning
* of the tree now.
*/
rq_next = eb32sc_first(&rqueue, tid_bit);
if (!rq_next) {
HA_ATOMIC_AND(&global_tasks_mask, ~tid_bit);
break;
}
}
t = eb32sc_entry(rq_next, struct task, rq);
rq_next = eb32sc_next(rq_next, tid_bit);
/* detach the task from the queue */
__task_unlink_rq(t);
__task_wakeup(t, &task_per_thread[tid].rqueue);
}
#endif
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);
} else {
if (!(active_tasks_mask & tid_bit)) {
activity[tid].empty_rq++;
return;
}
}
/* Get some tasks from the run queue, make sure we don't
* get too much in the task list, but put a bit more than
* the max that will be run, to give a bit more fairness
*/
rq_next = eb32sc_lookup_ge(&task_per_thread[tid].rqueue, rqueue_ticks - TIMER_LOOK_BACK, tid_bit);
while (max_processed + (max_processed / 10) > task_per_thread[tid].task_list_size) {
/* Note: this loop is one of the fastest code path in
* the whole program. It should not be re-arranged
* without a good reason.
*/
if (unlikely(!rq_next)) {
/* either we just started or we reached the end
* of the tree, typically because <rqueue_ticks>
* is in the first half and we're first scanning
* the last half. Let's loop back to the beginning
* of the tree now.
*/
rq_next = eb32sc_first(&task_per_thread[tid].rqueue, tid_bit);
if (!rq_next)
break;
}
t = eb32sc_entry(rq_next, struct task, rq);
rq_next = eb32sc_next(rq_next, tid_bit);
/* Make sure nobody re-adds the task in the runqueue */
HA_ATOMIC_OR(&t->state, TASK_RUNNING);
/* detach the task from the queue */
__task_unlink_rq(t);
/* And add it to the local task list */
task_insert_into_tasklet_list(t);
}
if (!(global_tasks_mask & tid_bit) && task_per_thread[tid].rqueue_size == 0) {
HA_ATOMIC_AND(&active_tasks_mask, ~tid_bit);
__ha_barrier_load();
if (global_tasks_mask & tid_bit)
HA_ATOMIC_OR(&active_tasks_mask, tid_bit);
}
while (max_processed > 0 && !LIST_ISEMPTY(&task_per_thread[tid].task_list)) {
struct task *t;
unsigned short state;
void *ctx;
struct task *(*process)(struct task *t, void *ctx, unsigned short state);
t = (struct task *)LIST_ELEM(task_per_thread[tid].task_list.n, struct tasklet *, list);
state = HA_ATOMIC_XCHG(&t->state, TASK_RUNNING);
__ha_barrier_store();
task_remove_from_task_list(t);
ctx = t->context;
process = t->process;
t->calls++;
curr_task = (struct task *)t;
if (likely(process == process_stream))
t = process_stream(t, ctx, state);
else {
if (t->process != NULL)
t = process(TASK_IS_TASKLET(t) ? NULL : t, ctx, state);
else {
__task_free(t);
t = NULL;
}
}
curr_task = NULL;
/* If there is a pending state we have to wake up the task
* immediately, else we defer it into wait queue
*/
if (t != NULL) {
state = HA_ATOMIC_AND(&t->state, ~TASK_RUNNING);
if (state)
#ifdef USE_THREAD
__task_wakeup(t, ((t->thread_mask & all_threads_mask) == tid_bit) ?
&task_per_thread[tid].rqueue : &rqueue);
#else
__task_wakeup(t, &task_per_thread[tid].rqueue);
#endif
else
task_queue(t);
}
max_processed--;
if (max_processed <= 0) {
HA_ATOMIC_OR(&active_tasks_mask, tid_bit);
activity[tid].long_rq++;
break;
}
}
}
/* perform minimal intializations, report 0 in case of error, 1 if OK. */
int init_task()
{
int i;
#ifdef USE_THREAD
memset(&timers, 0, sizeof(timers));
memset(&rqueue, 0, sizeof(rqueue));
#endif
HA_SPIN_INIT(&wq_lock);
HA_SPIN_INIT(&rq_lock);
memset(&task_per_thread, 0, sizeof(task_per_thread));
for (i = 0; i < MAX_THREADS; i++) {
LIST_INIT(&task_per_thread[i].task_list);
}
pool_head_task = create_pool("task", sizeof(struct task), MEM_F_SHARED);
if (!pool_head_task)
return 0;
pool_head_tasklet = create_pool("tasklet", sizeof(struct tasklet), MEM_F_SHARED);
if (!pool_head_tasklet)
return 0;
pool_head_notification = create_pool("notification", sizeof(struct notification), MEM_F_SHARED);
if (!pool_head_notification)
return 0;
return 1;
}
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/