This patch selects a preferred node for a task to run on based on the NUMA hinting faults. This information is later used to migrate tasks towards the node during balancing.
Signed-off-by: Mel Gorman <mgor...@suse.de> --- include/linux/sched.h | 1 + kernel/sched/core.c | 10 ++++++++++ kernel/sched/fair.c | 16 ++++++++++++++-- kernel/sched/sched.h | 1 + 4 files changed, 26 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 72861b4..ba46a64 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1507,6 +1507,7 @@ struct task_struct { struct callback_head numa_work; unsigned long *numa_faults; + int numa_preferred_nid; #endif /* CONFIG_NUMA_BALANCING */ struct rcu_head rcu; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f332ec0..019baae 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1593,6 +1593,7 @@ static void __sched_fork(struct task_struct *p) p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0; p->numa_scan_period = sysctl_numa_balancing_scan_delay; + p->numa_preferred_nid = -1; p->numa_work.next = &p->numa_work; p->numa_faults = NULL; #endif /* CONFIG_NUMA_BALANCING */ @@ -5713,6 +5714,15 @@ enum s_alloc { struct sched_domain_topology_level; +#ifdef CONFIG_NUMA_BALANCING + +/* Set a tasks preferred NUMA node */ +void sched_setnuma(struct task_struct *p, int nid) +{ + p->numa_preferred_nid = nid; +} +#endif /* CONFIG_NUMA_BALANCING */ + typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 904fd6f..f8c3f61 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -793,7 +793,8 @@ unsigned int sysctl_numa_balancing_scan_delay = 1000; static void task_numa_placement(struct task_struct *p) { - int seq; + int seq, nid, max_nid = 0; + unsigned long max_faults = 0; if (!p->mm) /* for example, ksmd faulting in a user's mm */ return; @@ -802,7 +803,18 @@ static void task_numa_placement(struct task_struct *p) return; p->numa_scan_seq = seq; - /* FIXME: Scheduling placement policy hints go here */ + /* Find the node with the highest number of faults */ + for (nid = 0; nid < nr_node_ids; nid++) { + unsigned long faults = p->numa_faults[nid]; + p->numa_faults[nid] >>= 1; + if (faults > max_faults) { + max_faults = faults; + max_nid = nid; + } + } + + if (max_faults && max_nid != p->numa_preferred_nid) + sched_setnuma(p, max_nid); } /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c5f773d..65a0cf0 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -504,6 +504,7 @@ DECLARE_PER_CPU(struct rq, runqueues); #define raw_rq() (&__raw_get_cpu_var(runqueues)) #ifdef CONFIG_NUMA_BALANCING +extern void sched_setnuma(struct task_struct *p, int nid); static inline void task_numa_free(struct task_struct *p) { kfree(p->numa_faults); -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/