[OPTIM] task_queue: assume most consecutive timers are equal
When queuing a timer, it's very likely that an expiration date is
equal to that of the previously queued timer, due to time rounding
to the millisecond. Optimizing for this case provides a noticeable
1% performance boost.
diff --git a/include/proto/task.h b/include/proto/task.h
index de50cba..cc5c180 100644
--- a/include/proto/task.h
+++ b/include/proto/task.h
@@ -35,6 +35,7 @@
extern unsigned int run_queue; /* run queue size */
extern unsigned int niced_tasks; /* number of niced tasks in the run queue */
extern struct pool_head *pool2_task;
+extern struct task *last_timer; /* optimization: last queued timer */
/* perform minimal initializations, report 0 in case of error, 1 if OK. */
int init_task();
@@ -63,11 +64,23 @@
* - wait queue
* A pointer to the task itself is returned.
*/
-static inline struct task *task_delete(struct task *t)
+static inline struct task *task_dequeue(struct task *t)
{
- if (t->eb.node.leaf_p)
+ if (likely(t->eb.node.leaf_p)) {
+ if (last_timer == t)
+ last_timer = NULL;
eb32_delete(&t->eb);
+ }
+ return t;
+}
+/*
+ * Unlinks the task and adjusts run queue stats.
+ * A pointer to the task itself is returned.
+ */
+static inline struct task *task_delete(struct task *t)
+{
+ task_dequeue(t);
if (t->state == TASK_RUNNING) {
run_queue--;
if (likely(t->nice))
diff --git a/src/task.c b/src/task.c
index b28ae0b..13d6817 100644
--- a/src/task.c
+++ b/src/task.c
@@ -25,6 +25,7 @@
unsigned int run_queue = 0;
unsigned int niced_tasks = 0; /* number of niced tasks in the run queue */
+struct task *last_timer = NULL; /* optimization: last queued timer */
/* Principle of the wait queue.
*
@@ -136,8 +137,7 @@
if (t->state == TASK_RUNNING)
return t;
- if (likely(t->eb.node.leaf_p))
- eb32_delete(&t->eb);
+ task_dequeue(t);
run_queue++;
t->eb.key = ++rqueue_ticks;
@@ -180,7 +180,18 @@
/* we're queuing too far away or in the past (most likely) */
return task;
#endif
+
+ if (likely(last_timer &&
+ last_timer->eb.key == task->eb.key &&
+ last_timer->eb.node.node_p)) {
+ /* Most often, last queued timer has the same expiration date, so
+ * if it's not queued at the root, let's queue a dup directly there.
+ */
+ eb_insert_dup(&last_timer->eb.node, &task->eb.node);
+ return task;
+ }
eb32_insert(&timers[ticks_to_tree(task->eb.key)], &task->eb);
+ last_timer = task;
return task;
}
@@ -280,7 +291,7 @@
if (likely(t->nice))
niced_tasks--;
t->state = TASK_IDLE;
- eb32_delete(&t->eb);
+ task_dequeue(t);
t->process(t, &temp);
tv_bound(next, &temp);