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This only introduces the flag and the mechanism to enable/disable this feature without affecting any scheduling behavior. Signed-off-by: Andrea Righi --- kernel/sched/ext.c | 21 +++++++++++++++++++-- kernel/sched/ext_idle.c | 33 +++++++++++++++++++++++++-------- kernel/sched/ext_idle.h | 6 ++++-- 3 files changed, 48 insertions(+), 12 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 8a9a30895381a..0063a646124bc 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -125,6 +125,12 @@ enum scx_ops_flags { */ SCX_OPS_SWITCH_PARTIAL = 1LLU << 3, + /* + * If set, enable per-node idle cpumasks. If clear, use a single global + * flat idle cpumask. + */ + SCX_OPS_BUILTIN_IDLE_PER_NODE = 1LLU << 4, + /* * CPU cgroup support flags */ @@ -134,6 +140,7 @@ enum scx_ops_flags { SCX_OPS_ENQ_LAST | SCX_OPS_ENQ_EXITING | SCX_OPS_SWITCH_PARTIAL | + SCX_OPS_BUILTIN_IDLE_PER_NODE | SCX_OPS_HAS_CGROUP_WEIGHT, }; @@ -3344,7 +3351,7 @@ static void handle_hotplug(struct rq *rq, bool online) atomic_long_inc(&scx_hotplug_seq); if (scx_enabled()) - scx_idle_update_selcpu_topology(); + scx_idle_update_selcpu_topology(&scx_ops); if (online && SCX_HAS_OP(cpu_online)) SCX_CALL_OP(SCX_KF_UNLOCKED, cpu_online, cpu); @@ -5116,6 +5123,16 @@ static int validate_ops(const struct sched_ext_ops *ops) return -EINVAL; } + /* + * SCX_OPS_BUILTIN_IDLE_PER_NODE requires built-in CPU idle + * selection policy to be enabled. + */ + if ((ops->flags & SCX_OPS_BUILTIN_IDLE_PER_NODE) && + (ops->update_idle && !(ops->flags & SCX_OPS_KEEP_BUILTIN_IDLE))) { + scx_ops_error("SCX_OPS_BUILTIN_IDLE_PER_NODE requires CPU idle selection enabled"); + return -EINVAL; + } + return 0; } @@ -5240,7 +5257,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) static_branch_enable_cpuslocked(&scx_has_op[i]); check_hotplug_seq(ops); - scx_idle_update_selcpu_topology(); + scx_idle_update_selcpu_topology(ops); cpus_read_unlock(); diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index cb981956005b4..a3f2b00903ac2 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -14,6 +14,9 @@ /* Enable/disable built-in idle CPU selection policy */ DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_enabled); +/* Enable/disable per-node idle cpumasks */ +DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_per_node); + #ifdef CONFIG_SMP #ifdef CONFIG_CPUMASK_OFFSTACK #define CL_ALIGNED_IF_ONSTACK @@ -204,9 +207,9 @@ static bool llc_numa_mismatch(void) * CPU belongs to a single LLC domain, and that each LLC domain is entirely * contained within a single NUMA node. */ -void scx_idle_update_selcpu_topology(void) +void scx_idle_update_selcpu_topology(struct sched_ext_ops *ops) { - bool enable_llc = false, enable_numa = false; + bool enable_llc = false, enable_numa = false, enable_idle_node = false; unsigned int nr_cpus; s32 cpu = cpumask_first(cpu_online_mask); @@ -237,13 +240,21 @@ void scx_idle_update_selcpu_topology(void) * If all CPUs belong to the same NUMA node and the same LLC domain, * enabling both NUMA and LLC optimizations is unnecessary, as checking * for an idle CPU in the same domain twice is redundant. + * + * If SCX_OPS_BUILTIN_IDLE_PER_NODE is enabled ignore the NUMA + * optimization, as we would naturally select idle CPUs within + * specific NUMA nodes querying the corresponding per-node cpumask. */ - nr_cpus = numa_weight(cpu); - if (nr_cpus > 0) { - if (nr_cpus < num_online_cpus() && llc_numa_mismatch()) - enable_numa = true; - pr_debug("sched_ext: NUMA=%*pb weight=%u\n", - cpumask_pr_args(numa_span(cpu)), numa_weight(cpu)); + if (ops->flags & SCX_OPS_BUILTIN_IDLE_PER_NODE) { + enable_idle_node = true; + } else { + nr_cpus = numa_weight(cpu); + if (nr_cpus > 0) { + if (nr_cpus < num_online_cpus() && llc_numa_mismatch()) + enable_numa = true; + pr_debug("sched_ext: NUMA=%*pb weight=%u\n", + cpumask_pr_args(numa_span(cpu)), numa_weight(cpu)); + } } rcu_read_unlock(); @@ -251,6 +262,8 @@ void scx_idle_update_selcpu_topology(void) str_enabled_disabled(enable_llc)); pr_debug("sched_ext: NUMA idle selection %s\n", str_enabled_disabled(enable_numa)); + pr_debug("sched_ext: per-node idle cpumask %s\n", + str_enabled_disabled(enable_idle_node)); if (enable_llc) static_branch_enable_cpuslocked(&scx_selcpu_topo_llc); @@ -260,6 +273,10 @@ void scx_idle_update_selcpu_topology(void) static_branch_enable_cpuslocked(&scx_selcpu_topo_numa); else static_branch_disable_cpuslocked(&scx_selcpu_topo_numa); + if (enable_idle_node) + static_branch_enable_cpuslocked(&scx_builtin_idle_per_node); + else + static_branch_disable_cpuslocked(&scx_builtin_idle_per_node); } /* diff --git a/kernel/sched/ext_idle.h b/kernel/sched/ext_idle.h index 7a13a74815ba7..d005bd22c19a5 100644 --- a/kernel/sched/ext_idle.h +++ b/kernel/sched/ext_idle.h @@ -10,19 +10,21 @@ #ifndef _KERNEL_SCHED_EXT_IDLE_H #define _KERNEL_SCHED_EXT_IDLE_H +struct sched_ext_ops; + extern struct static_key_false scx_builtin_idle_enabled; #ifdef CONFIG_SMP extern struct static_key_false scx_selcpu_topo_llc; extern struct static_key_false scx_selcpu_topo_numa; -void scx_idle_update_selcpu_topology(void); +void scx_idle_update_selcpu_topology(struct sched_ext_ops *ops); void scx_idle_reset_masks(void); void scx_idle_init_masks(void); bool scx_idle_test_and_clear_cpu(int cpu); s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, u64 flags); #else /* !CONFIG_SMP */ -static inline void scx_idle_update_selcpu_topology(void) {} +static inline void scx_idle_update_selcpu_topology(struct sched_ext_ops *ops) {} static inline void scx_idle_reset_masks(void) {} static inline void scx_idle_init_masks(void) {} static inline bool scx_idle_test_and_clear_cpu(int cpu) { return false; }