| From a6ccb0c9d3c6cf362ea51064e25e7ddbcd7c6535 Mon Sep 17 00:00:00 2001 |
| From: Valentin Schneider <valentin.schneider@arm.com> |
| Date: Mon, 3 Jun 2019 12:54:24 +0100 |
| Subject: [PATCH] sched/fair: Clean up definition of NOHZ blocked load |
| functions |
| |
| commit b0c792244138d3ef099e7fce978675dc4acae570 upstream. |
| |
| cfs_rq_has_blocked() and others_have_blocked() are only used within |
| update_blocked_averages(). The !CONFIG_FAIR_GROUP_SCHED version of the |
| latter calls them within a #define CONFIG_NO_HZ_COMMON block, whereas |
| the CONFIG_FAIR_GROUP_SCHED one calls them unconditionnally. |
| |
| As reported by Qian, the above leads to this warning in |
| !CONFIG_NO_HZ_COMMON configs: |
| |
| kernel/sched/fair.c: In function 'update_blocked_averages': |
| kernel/sched/fair.c:7750:7: warning: variable 'done' set but not used [-Wunused-but-set-variable] |
| |
| It wouldn't be wrong to keep cfs_rq_has_blocked() and |
| others_have_blocked() as they are, but since their only current use is |
| to figure out when we can stop calling update_blocked_averages() on |
| fully decayed NOHZ idle CPUs, we can give them a new definition for |
| !CONFIG_NO_HZ_COMMON. |
| |
| Change the definition of cfs_rq_has_blocked() and |
| others_have_blocked() for !CONFIG_NO_HZ_COMMON so that the |
| NOHZ-specific blocks of update_blocked_averages() become no-ops and |
| the 'done' variable gets optimised out. |
| |
| While at it, remove the CONFIG_NO_HZ_COMMON block from the |
| !CONFIG_FAIR_GROUP_SCHED definition of update_blocked_averages() by |
| using the newly-introduced update_blocked_load_status() helper. |
| |
| No change in functionality intended. |
| |
| [ Additions by Peter Zijlstra. ] |
| |
| Reported-by: Qian Cai <cai@lca.pw> |
| Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Acked-by: Vincent Guittot <vincent.guittot@linaro.org> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Link: https://lkml.kernel.org/r/20190603115424.7951-1-valentin.schneider@arm.com |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c |
| index 866dd0cbc920..fa3288bb0b07 100644 |
| --- a/kernel/sched/fair.c |
| +++ b/kernel/sched/fair.c |
| @@ -7697,6 +7697,7 @@ static void attach_tasks(struct lb_env *env) |
| rq_unlock(env->dst_rq, &rf); |
| } |
| |
| +#ifdef CONFIG_NO_HZ_COMMON |
| static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) |
| { |
| if (cfs_rq->avg.load_avg) |
| @@ -7724,6 +7725,19 @@ static inline bool others_have_blocked(struct rq *rq) |
| return false; |
| } |
| |
| +static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) |
| +{ |
| + rq->last_blocked_load_update_tick = jiffies; |
| + |
| + if (!has_blocked) |
| + rq->has_blocked_load = 0; |
| +} |
| +#else |
| +static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) { return false; } |
| +static inline bool others_have_blocked(struct rq *rq) { return false; } |
| +static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {} |
| +#endif |
| + |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| |
| static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) |
| @@ -7794,11 +7808,7 @@ static void update_blocked_averages(int cpu) |
| done = false; |
| } |
| |
| -#ifdef CONFIG_NO_HZ_COMMON |
| - rq->last_blocked_load_update_tick = jiffies; |
| - if (done) |
| - rq->has_blocked_load = 0; |
| -#endif |
| + update_blocked_load_status(rq, !done); |
| rq_unlock_irqrestore(rq, &rf); |
| } |
| |
| @@ -7870,11 +7880,7 @@ static inline void update_blocked_averages(int cpu) |
| |
| update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq); |
| |
| -#ifdef CONFIG_NO_HZ_COMMON |
| - rq->last_blocked_load_update_tick = jiffies; |
| - if (!cfs_rq_has_blocked(cfs_rq) && !others_have_blocked(rq)) |
| - rq->has_blocked_load = 0; |
| -#endif |
| + update_blocked_load_status(rq, cfs_rq_has_blocked(cfs_rq) || others_have_blocked(rq)); |
| rq_unlock_irqrestore(rq, &rf); |
| } |
| |
| -- |
| 2.7.4 |
| |