Messages in this thread Patch in this message |  | | From | Mel Gorman <> | Subject | [PATCH 6/9] sched/fair: Make select_idle_cpu() proportional to cores | Date | Mon, 26 Jul 2021 11:22:44 +0100 |
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From: Peter Zijlstra (Intel) <peterz@infradead.org>
Instead of calculating how many (logical) CPUs to scan, compute how many cores to scan.
This changes behaviour for anything !SMT2.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- kernel/sched/core.c | 17 ++++++++++++----- kernel/sched/fair.c | 11 +++++++++-- kernel/sched/sched.h | 2 ++ 3 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2d9ff40f4661..7c073b67f1ea 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8647,11 +8647,18 @@ int sched_cpu_activate(unsigned int cpu) balance_push_set(cpu, false); #ifdef CONFIG_SCHED_SMT - /* - * When going up, increment the number of cores with SMT present. - */ - if (cpumask_weight(cpu_smt_mask(cpu)) == 2) - static_branch_inc_cpuslocked(&sched_smt_present); + do { + int weight = cpumask_weight(cpu_smt_mask(cpu)); + + if (weight > sched_smt_weight) + sched_smt_weight = weight; + + /* + * When going up, increment the number of cores with SMT present. + */ + if (cpumask_weight(cpu_smt_mask(cpu)) == 2) + static_branch_inc_cpuslocked(&sched_smt_present); + } while (0); #endif set_cpu_active(cpu, true); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 125c020746b8..20b9255ebf97 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6076,6 +6076,8 @@ static inline int __select_idle_cpu(int cpu, struct task_struct *p) DEFINE_STATIC_KEY_FALSE(sched_smt_present); EXPORT_SYMBOL_GPL(sched_smt_present); +int __read_mostly sched_smt_weight = 1; + static inline void set_idle_cores(int cpu, int val) { struct sched_domain_shared *sds; @@ -6194,6 +6196,8 @@ static inline bool test_idle_cores(int cpu, bool def) return def; } +#define sched_smt_weight 1 + static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu) { return __select_idle_cpu(core, p); @@ -6206,6 +6210,8 @@ static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd #endif /* CONFIG_SCHED_SMT */ +#define sis_min_cores 2 + /* * Scan the LLC domain for idle CPUs; this is dynamically regulated by * comparing the average scan cost (tracked in sd->avg_scan_cost) against the @@ -6246,11 +6252,12 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool avg_cost = this_sd->avg_scan_cost + 1; span_avg = sd->span_weight * avg_idle; - if (span_avg > 4*avg_cost) + if (span_avg > sis_min_cores * avg_cost) nr = div_u64(span_avg, avg_cost); else - nr = 4; + nr = sis_min_cores; + nr *= sched_smt_weight; time = cpu_clock(this); } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index e31179e6c6ff..4d47a0969710 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1351,6 +1351,8 @@ do { \ #ifdef CONFIG_SCHED_SMT extern void __update_idle_core(struct rq *rq); +extern int sched_smt_weight; + static inline void update_idle_core(struct rq *rq) { if (static_branch_unlikely(&sched_smt_present)) -- 2.26.2
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