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authorValentin Schneider <valentin.schneider@arm.com>2019-06-03 12:54:24 +0100
committerIngo Molnar <mingo@kernel.org>2019-06-17 12:15:57 +0200
commitb0c792244138d3ef099e7fce978675dc4acae570 (patch)
tree6ab9f005b7c25cd08716e67c9c51a54413c577fc /kernel/sched
parente3b929b0a184edb35531153c5afcaebb09014f9d (diff)
sched/fair: Clean up definition of NOHZ blocked load functions
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>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c26
1 files changed, 16 insertions, 10 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7f8d477f90fe..4c8f45ed093c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7393,6 +7393,7 @@ 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)
@@ -7420,6 +7421,19 @@ 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)
@@ -7485,11 +7499,7 @@ static void update_blocked_averages(int cpu)
if (others_have_blocked(rq))
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);
}
@@ -7555,11 +7565,7 @@ static inline void update_blocked_averages(int cpu)
update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
update_irq_load_avg(rq, 0);
-#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);
}