list_head_init(&timers->far);
timers->base = time_to_grains(start);
timers->first = -1ULL;
+ memset(timers->firsts, 0xFF, sizeof(timers->firsts));
for (i = 0; i < ARRAY_SIZE(timers->level); i++)
timers->level[i] = NULL;
}
{
struct list_head *l;
unsigned int level = level_of(timers, t->time);
+ uint64_t *first;
- if (!timers->level[level])
+ if (!timers->level[level]) {
l = &timers->far;
- else {
+ first = &timers->firsts[ARRAY_SIZE(timers->level)];
+ } else {
int off = (t->time >> (level*TIMER_LEVEL_BITS)) & (PER_LEVEL-1);
l = &timers->level[level]->list[off];
+ first = &timers->firsts[level];
}
list_add_tail(l, &t->list);
+ if (t->time < *first)
+ *first = t->time;
}
void timer_init(struct timer *t)
return prev;
}
+/* Update level's first watermark, and return overall first. */
+static const struct timer *first_for_level(struct timers *timers,
+ size_t level,
+ const struct timer *level_first,
+ const struct timer *first)
+{
+ if (level_first) {
+ timers->firsts[level] = level_first->time;
+ if (!first || level_first->time < first->time)
+ first = level_first;
+ } else {
+ timers->firsts[level] = -1ULL;
+ }
+ return first;
+}
+
+static bool level_may_beat(const struct timers *timers, size_t level,
+ const struct timer *first)
+{
+ return !first || timers->firsts[level] < first->time;
+}
+
/* FIXME: Suboptimal */
-static const struct timer *brute_force_first(const struct timers *timers)
+static const struct timer *brute_force_first(struct timers *timers)
{
unsigned int l, i;
const struct timer *found = NULL;
for (l = 0; l < ARRAY_SIZE(timers->level) && timers->level[l]; l++) {
+ const struct timer *t = NULL;
+
+ /* Do we know they don't have a better one? */
+ if (!level_may_beat(timers, l, found))
+ continue;
+
+ /* Find first timer on this level. */
for (i = 0; i < PER_LEVEL; i++)
- found = find_first(&timers->level[l]->list[i], l,
- found);
+ t = find_first(&timers->level[l]->list[i], l, t);
+
+ found = first_for_level(timers, l, t, found);
+ }
+
+ /* Check (and update) far list if there's a chance. */
+ l = ARRAY_SIZE(timers->level);
+ if (level_may_beat(timers, l, found)) {
+ const struct timer *t = find_first(&timers->far, l, NULL);
+ found = first_for_level(timers, l, t, found);
}
- found = find_first(&timers->far, -1U, found);
return found;
}
-
-static const struct timer *get_first(const struct timers *timers)
-{
- uint64_t time;
-
- /* Where can we start from? */
- if (timers->first < timers->base)
- time = timers->base;
- else
- time = timers->first;
+static const struct timer *get_first(struct timers *timers)
+{
/* We can have just far timers, for example. */
if (timers->level[0]) {
/* First search rest of lower buckets; we've already spilled
* so if we find one there we don't need to search further. */
- unsigned int i, off = time % PER_LEVEL;
+ unsigned int i, off = timers->base % PER_LEVEL;
for (i = off; i < PER_LEVEL; i++) {
struct list_head *h = &timers->level[0]->list[i];
if (!found) {
timers->first = -1ULL;
return false;
- }
+ }
timers->first = found->time;
return true;
h = &timers->level[l]->list[(i+off) % PER_LEVEL];
if (!timer_list_check(h, timers->base + i, timers->base + i,
- timers->first, abortstr))
+ timers->firsts[l], abortstr))
return NULL;
}
h = &timers->level[l]->list[(i+off) % PER_LEVEL];
if (!timer_list_check(h, base, base + per_bucket - 1,
- timers->first, abortstr))
+ timers->firsts[l], abortstr))
return NULL;
base += per_bucket;
}
past_levels:
base = (timers->base & ~((1ULL << (TIMER_LEVEL_BITS * l)) - 1))
+ (1ULL << (TIMER_LEVEL_BITS * l)) - 1;
- if (!timer_list_check(&timers->far, base, -1ULL, timers->first,
+ if (!timer_list_check(&timers->far, base, -1ULL,
+ timers->firsts[ARRAY_SIZE(timers->level)],
abortstr))
return NULL;