diff options
author | Ingo Molnar <mingo@elte.hu> | 2007-08-10 21:05:11 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2007-08-10 21:05:11 (GMT) |
commit | 529c77261bccd9d37f110f58b0753d95beaa9fa2 (patch) | |
tree | fff049581ceaa06591ba07938bb370a0ccee7293 | |
parent | ac07860264bd2b18834d3fa3be47032115524cea (diff) | |
download | linux-fsl-qoriq-529c77261bccd9d37f110f58b0753d95beaa9fa2.tar.xz |
sched: improve rq-clock overflow logic
improve the rq-clock overflow logic: limit the absolute rq->clock
delta since the last scheduler tick, instead of limiting the delta
itself.
tested by Arjan van de Ven - whole laptop was misbehaving due to
an incorrectly calibrated cpu_khz confusing sched_clock().
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
-rw-r--r-- | kernel/sched.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index b0afd8d..6247e4a 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -263,6 +263,7 @@ struct rq { unsigned int clock_warps, clock_overflows; unsigned int clock_unstable_events; + u64 tick_timestamp; atomic_t nr_iowait; @@ -341,8 +342,11 @@ static void __update_rq_clock(struct rq *rq) /* * Catch too large forward jumps too: */ - if (unlikely(delta > 2*TICK_NSEC)) { - clock++; + if (unlikely(clock + delta > rq->tick_timestamp + TICK_NSEC)) { + if (clock < rq->tick_timestamp + TICK_NSEC) + clock = rq->tick_timestamp + TICK_NSEC; + else + clock++; rq->clock_overflows++; } else { if (unlikely(delta > rq->clock_max_delta)) @@ -3308,9 +3312,16 @@ void scheduler_tick(void) int cpu = smp_processor_id(); struct rq *rq = cpu_rq(cpu); struct task_struct *curr = rq->curr; + u64 next_tick = rq->tick_timestamp + TICK_NSEC; spin_lock(&rq->lock); __update_rq_clock(rq); + /* + * Let rq->clock advance by at least TICK_NSEC: + */ + if (unlikely(rq->clock < next_tick)) + rq->clock = next_tick; + rq->tick_timestamp = rq->clock; update_cpu_load(rq); if (curr != rq->idle) /* FIXME: needed? */ curr->sched_class->task_tick(rq, curr); |