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author | Guillaume Chazarain <guichaz@yahoo.fr> | 2008-04-19 17:44:57 (GMT) |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-04-19 17:44:57 (GMT) |
commit | 15934a37324f32e0fda633dc7984a671ea81cd75 (patch) | |
tree | 1f65ac7d910e76b65d0cfcd1c72e156b0a8bd273 /kernel/sched.c | |
parent | 30914a58af9d21c5f1831adabb5d7a800a378675 (diff) | |
download | linux-fsl-qoriq-15934a37324f32e0fda633dc7984a671ea81cd75.tar.xz |
sched: fix rq->clock overflows detection with CONFIG_NO_HZ
When using CONFIG_NO_HZ, rq->tick_timestamp is not updated every TICK_NSEC.
We check that the number of skipped ticks matches the clock jump seen in
__update_rq_clock().
Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r-- | kernel/sched.c | 38 |
1 files changed, 35 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 7fe334e..d8456a9 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -397,6 +397,7 @@ struct rq { unsigned long cpu_load[CPU_LOAD_IDX_MAX]; unsigned char idle_at_tick; #ifdef CONFIG_NO_HZ + unsigned long last_tick_seen; unsigned char in_nohz_recently; #endif /* capture load from *all* tasks on this cpu: */ @@ -500,6 +501,32 @@ static inline int cpu_of(struct rq *rq) #endif } +#ifdef CONFIG_NO_HZ +static inline bool nohz_on(int cpu) +{ + return tick_get_tick_sched(cpu)->nohz_mode != NOHZ_MODE_INACTIVE; +} + +static inline u64 max_skipped_ticks(struct rq *rq) +{ + return nohz_on(cpu_of(rq)) ? jiffies - rq->last_tick_seen + 2 : 1; +} + +static inline void update_last_tick_seen(struct rq *rq) +{ + rq->last_tick_seen = jiffies; +} +#else +static inline u64 max_skipped_ticks(struct rq *rq) +{ + return 1; +} + +static inline void update_last_tick_seen(struct rq *rq) +{ +} +#endif + /* * Update the per-runqueue clock, as finegrained as the platform can give * us, but without assuming monotonicity, etc.: @@ -524,9 +551,12 @@ static void __update_rq_clock(struct rq *rq) /* * Catch too large forward jumps too: */ - if (unlikely(clock + delta > rq->tick_timestamp + TICK_NSEC)) { - if (clock < rq->tick_timestamp + TICK_NSEC) - clock = rq->tick_timestamp + TICK_NSEC; + u64 max_jump = max_skipped_ticks(rq) * TICK_NSEC; + u64 max_time = rq->tick_timestamp + max_jump; + + if (unlikely(clock + delta > max_time)) { + if (clock < max_time) + clock = max_time; else clock++; rq->clock_overflows++; @@ -3812,6 +3842,7 @@ void scheduler_tick(void) rq->clock_underflows++; } rq->tick_timestamp = rq->clock; + update_last_tick_seen(rq); update_cpu_load(rq); curr->sched_class->task_tick(rq, curr, 0); update_sched_rt_period(rq); @@ -7261,6 +7292,7 @@ void __init sched_init(void) lockdep_set_class(&rq->lock, &rq->rq_lock_key); rq->nr_running = 0; rq->clock = 1; + update_last_tick_seen(rq); init_cfs_rq(&rq->cfs, rq); init_rt_rq(&rq->rt, rq); #ifdef CONFIG_FAIR_GROUP_SCHED |