diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/ext_idle.c | 48 |
1 files changed, 44 insertions, 4 deletions
diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index 5d6253c6ed90..f39b34fbb8a6 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -49,6 +49,7 @@ static struct scx_idle_cpus **scx_idle_node_masks; /* * Local per-CPU cpumasks (used to generate temporary idle cpumasks). */ +static DEFINE_PER_CPU(cpumask_var_t, local_idle_cpumask); static DEFINE_PER_CPU(cpumask_var_t, local_llc_idle_cpumask); static DEFINE_PER_CPU(cpumask_var_t, local_numa_idle_cpumask); @@ -417,13 +418,15 @@ static inline bool task_affinity_all(const struct task_struct *p) * branch prediction optimizations. * * 3. Pick a CPU within the same LLC (Last-Level Cache): - * - if the above conditions aren't met, pick a CPU that shares the same LLC - * to maintain cache locality. + * - if the above conditions aren't met, pick a CPU that shares the same + * LLC, if the LLC domain is a subset of @cpus_allowed, to maintain + * cache locality. * * 4. Pick a CPU within the same NUMA node, if enabled: - * - choose a CPU from the same NUMA node to reduce memory access latency. + * - choose a CPU from the same NUMA node, if the node cpumask is a + * subset of @cpus_allowed, to reduce memory access latency. * - * 5. Pick any idle CPU usable by the task. + * 5. Pick any idle CPU within the @cpus_allowed domain. * * Step 3 and 4 are performed only if the system has, respectively, * multiple LLCs / multiple NUMA nodes (see scx_selcpu_topo_llc and @@ -446,6 +449,39 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, int node = scx_cpu_node_if_enabled(prev_cpu); s32 cpu; + preempt_disable(); + + /* + * Determine the subset of CPUs usable by @p within @cpus_allowed. + */ + if (allowed != p->cpus_ptr) { + struct cpumask *local_cpus = this_cpu_cpumask_var_ptr(local_idle_cpumask); + + if (task_affinity_all(p)) { + allowed = cpus_allowed; + } else if (cpumask_and(local_cpus, cpus_allowed, p->cpus_ptr)) { + allowed = local_cpus; + } else { + cpu = -EBUSY; + goto out_enable; + } + + /* + * If @prev_cpu is not in the allowed CPUs, skip topology + * optimizations and try to pick any idle CPU usable by the + * task. + * + * If %SCX_OPS_BUILTIN_IDLE_PER_NODE is enabled, prioritize + * the current node, as it may optimize some waker->wakee + * workloads. + */ + if (!cpumask_test_cpu(prev_cpu, allowed)) { + node = scx_cpu_node_if_enabled(smp_processor_id()); + cpu = scx_pick_idle_cpu(allowed, node, flags); + goto out_enable; + } + } + /* * This is necessary to protect llc_cpus. */ @@ -610,6 +646,8 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, out_unlock: rcu_read_unlock(); +out_enable: + preempt_enable(); return cpu; } @@ -641,6 +679,8 @@ void scx_idle_init_masks(void) /* Allocate local per-cpu idle cpumasks */ for_each_possible_cpu(i) { + BUG_ON(!alloc_cpumask_var_node(&per_cpu(local_idle_cpumask, i), + GFP_KERNEL, cpu_to_node(i))); BUG_ON(!alloc_cpumask_var_node(&per_cpu(local_llc_idle_cpumask, i), GFP_KERNEL, cpu_to_node(i))); BUG_ON(!alloc_cpumask_var_node(&per_cpu(local_numa_idle_cpumask, i), |