Messages in this thread Patch in this message | | | Subject | [2.6.16-mm1 patch] throttling tree patches | From | Mike Galbraith <> | Date | Fri, 24 Mar 2006 12:03:28 +0100 |
| |
Greetings,
I've broken down my throttling tree into 6 patches, which I'll send as replies to this start-point.
Patch 1/6
Ignore timewarps caused by SMP timestamp rounding. Also, don't stamp a task with a computed timestamp, stamp with the already called clock.
Signed-off-by: Mike Galbraith <efault@gmx.de>
--- linux-2.6.16-mm1/kernel/sched.c.org 2006-03-23 15:01:41.000000000 +0100 +++ linux-2.6.16-mm1/kernel/sched.c 2006-03-23 15:02:25.000000000 +0100 @@ -805,6 +805,16 @@ unsigned long long __sleep_time = now - p->timestamp; unsigned long sleep_time; + /* + * On SMP systems, a task can go to sleep on one CPU and + * wake up on another. When this happens, the timestamp + * is rounded to the nearest tick, which can lead to now + * being less than p->timestamp for short sleeps. Ignore + * these, they're insignificant. + */ + if (unlikely(now < p->timestamp)) + __sleep_time = 0ULL; + if (batch_task(p)) sleep_time = 0; else { @@ -871,20 +881,20 @@ */ static void activate_task(task_t *p, runqueue_t *rq, int local) { - unsigned long long now; + unsigned long long now, comp; - now = sched_clock(); + now = comp = sched_clock(); #ifdef CONFIG_SMP if (!local) { /* Compensate for drifting sched_clock */ runqueue_t *this_rq = this_rq(); - now = (now - this_rq->timestamp_last_tick) + comp = (now - this_rq->timestamp_last_tick) + rq->timestamp_last_tick; } #endif if (!rt_task(p)) - p->prio = recalc_task_prio(p, now); + p->prio = recalc_task_prio(p, comp); /* * This checks to make sure it's not an uninterruptible task
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |