From 529c77261bccd9d37f110f58b0753d95beaa9fa2 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 10 Aug 2007 23:05:11 +0200 Subject: [PATCH] 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 Signed-off-by: Arjan van de Ven --- kernel/sched.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index b0afd8db1396..6247e4a8350f 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); -- 2.20.1