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| author | Venkatesh Pallipadi <venki@google.com> | 2010-10-04 17:03:22 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-10-18 20:52:27 +0200 |
| commit | aa483808516ca5cacfa0e5849691f64fec25828e (patch) | |
| tree | 38a1d9f1cb1157bd68dc2475447bacbb4b63c64a /kernel | |
| parent | 305e6835e05513406fa12820e40e4a8ecb63743c (diff) | |
| download | linux-stable-aa483808516ca5cacfa0e5849691f64fec25828e.tar.gz linux-stable-aa483808516ca5cacfa0e5849691f64fec25828e.tar.bz2 linux-stable-aa483808516ca5cacfa0e5849691f64fec25828e.zip | |
sched: Remove irq time from available CPU power
The idea was suggested by Peter Zijlstra here:
http://marc.info/?l=linux-kernel&m=127476934517534&w=2
irq time is technically not available to the tasks running on the CPU.
This patch removes irq time from CPU power piggybacking on
sched_rt_avg_update().
Tested this by keeping CPU X busy with a network intensive task having 75%
oa a single CPU irq processing (hard+soft) on a 4-way system. And start seven
cycle soakers on the system. Without this change, there will be two tasks on
each CPU. With this change, there is a single task on irq busy CPU X and
remaining 7 tasks are spread around among other 3 CPUs.
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-8-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 18 | ||||
| -rw-r--r-- | kernel/sched_fair.c | 8 | ||||
| -rw-r--r-- | kernel/sched_features.h | 5 |
3 files changed, 30 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 9e01b7100ef6..bff9ef537df0 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -519,6 +519,10 @@ struct rq { u64 avg_idle; #endif +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + u64 prev_irq_time; +#endif + /* calc_load related fields */ unsigned long calc_load_update; long calc_load_active; @@ -643,6 +647,7 @@ static inline struct task_group *task_group(struct task_struct *p) #endif /* CONFIG_CGROUP_SCHED */ static u64 irq_time_cpu(int cpu); +static void sched_irq_time_avg_update(struct rq *rq, u64 irq_time); inline void update_rq_clock(struct rq *rq) { @@ -654,6 +659,8 @@ inline void update_rq_clock(struct rq *rq) irq_time = irq_time_cpu(cpu); if (rq->clock - irq_time > rq->clock_task) rq->clock_task = rq->clock - irq_time; + + sched_irq_time_avg_update(rq, irq_time); } } @@ -1985,6 +1992,15 @@ void account_system_vtime(struct task_struct *curr) local_irq_restore(flags); } +static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) +{ + if (sched_clock_irqtime && sched_feat(NONIRQ_POWER)) { + u64 delta_irq = curr_irq_time - rq->prev_irq_time; + rq->prev_irq_time = curr_irq_time; + sched_rt_avg_update(rq, delta_irq); + } +} + #else static u64 irq_time_cpu(int cpu) @@ -1992,6 +2008,8 @@ static u64 irq_time_cpu(int cpu) return 0; } +static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) { } + #endif #include "sched_idletask.c" diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index c358d4081b81..74cccfae87a8 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -2275,7 +2275,13 @@ unsigned long scale_rt_power(int cpu) u64 total, available; total = sched_avg_period() + (rq->clock - rq->age_stamp); - available = total - rq->rt_avg; + + if (unlikely(total < rq->rt_avg)) { + /* Ensures that power won't end up being negative */ + available = 0; + } else { + available = total - rq->rt_avg; + } if (unlikely((s64)total < SCHED_LOAD_SCALE)) total = SCHED_LOAD_SCALE; diff --git a/kernel/sched_features.h b/kernel/sched_features.h index 83c66e8ad3ee..185f920ec1a2 100644 --- a/kernel/sched_features.h +++ b/kernel/sched_features.h @@ -61,3 +61,8 @@ SCHED_FEAT(ASYM_EFF_LOAD, 1) * release the lock. Decreases scheduling overhead. */ SCHED_FEAT(OWNER_SPIN, 1) + +/* + * Decrement CPU power based on irq activity + */ +SCHED_FEAT(NONIRQ_POWER, 1) |