From 398ba2b0cc0a43964fe3d2dd19cb2a478f1f220b Mon Sep 17 00:00:00 2001 From: Abel Wu Date: Wed, 7 Sep 2022 19:19:59 +0800 Subject: sched/fair: Default to false in test_idle_cores() It's uncertain whether idle cores exist or not if shared sched- domains are not ready, so returning "no idle cores" usually makes sense. While __update_idle_core() is an exception, it checks status of this core and set hint to shared sched-domain if necessary. So the whole logic of this function depends on the existence of shared sched-domain, and can certainly bail out early if it is not available. It's somehow a little tricky, and as Josh suggested that it should be transient while the domain isn't ready. So remove the self-defined default value to make things more clearer. Signed-off-by: Abel Wu Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Josh Don Acked-by: Mel Gorman Link: https://lore.kernel.org/r/20220907112000.1854-5-wuyun.abel@bytedance.com --- kernel/sched/fair.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'kernel/sched') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 03ce65068333..23b020c3d3a0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1588,11 +1588,11 @@ numa_type numa_classify(unsigned int imbalance_pct, #ifdef CONFIG_SCHED_SMT /* Forward declarations of select_idle_sibling helpers */ -static inline bool test_idle_cores(int cpu, bool def); +static inline bool test_idle_cores(int cpu); static inline int numa_idle_core(int idle_core, int cpu) { if (!static_branch_likely(&sched_smt_present) || - idle_core >= 0 || !test_idle_cores(cpu, false)) + idle_core >= 0 || !test_idle_cores(cpu)) return idle_core; /* @@ -6271,7 +6271,7 @@ static inline void set_idle_cores(int cpu, int val) WRITE_ONCE(sds->has_idle_cores, val); } -static inline bool test_idle_cores(int cpu, bool def) +static inline bool test_idle_cores(int cpu) { struct sched_domain_shared *sds; @@ -6279,7 +6279,7 @@ static inline bool test_idle_cores(int cpu, bool def) if (sds) return READ_ONCE(sds->has_idle_cores); - return def; + return false; } /* @@ -6295,7 +6295,7 @@ void __update_idle_core(struct rq *rq) int cpu; rcu_read_lock(); - if (test_idle_cores(core, true)) + if (test_idle_cores(core)) goto unlock; for_each_cpu(cpu, cpu_smt_mask(core)) { @@ -6367,9 +6367,9 @@ static inline void set_idle_cores(int cpu, int val) { } -static inline bool test_idle_cores(int cpu, bool def) +static inline bool test_idle_cores(int cpu) { - return def; + return false; } static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu) @@ -6608,7 +6608,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) return target; if (sched_smt_active()) { - has_idle_core = test_idle_cores(target, false); + has_idle_core = test_idle_cores(target); if (!has_idle_core && cpus_share_cache(prev, target)) { i = select_idle_smt(p, prev); -- cgit v1.2.3