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OPTIM: stick-table: avoid atomic ops in stktable_requeue_exp() when possible

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Since the task's time resolution is the millisecond we know there
will not be more than 1000 useful updates per second, so there's no
point in doing a CAS and a task_queue() for each call, better first
check if we're going to change the date. Now we're certain not to
perform such operations more than 1000 times a second for a given
table.

The loop was modified because this improvement will also be used to fix a
bug later.
This commit is contained in:
Willy Tarreau 2022-11-14 17:54:07 +01:00
parent 6342714052
commit 3238f79d12
1 changed files with 10 additions and 4 deletions
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14
src/stick_table.c
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@ -550,11 +550,17 @@ void stktable_requeue_exp(struct stktable *t, const struct stksess *ts)
/* set the task's expire to the newest expiration date. */
old_exp = HA_ATOMIC_LOAD(&t->exp_task->expire);
do {
new_exp = tick_first(expire, old_exp);
/* let's not go further if we're already up to date */
if (new_exp == old_exp)
return;
while (new_exp != old_exp &&
!HA_ATOMIC_CAS(&t->exp_task->expire, &old_exp, new_exp)) {
__ha_cpu_relax();
new_exp = tick_first(expire, old_exp);
} while (new_exp != old_exp &&
!HA_ATOMIC_CAS(&t->exp_task->expire, &old_exp, new_exp) &&
__ha_cpu_relax());
}
task_queue(t->exp_task);
}