From: Rik van Riel <r...@redhat.com> commit 20e07dea286a90f096a779706861472d296397c6 upstream
The numa_faults_cpu statistics are used to maintain an active_nodes nodemask per numa_group. This allows us to be smarter about when to do numa migrations. Signed-off-by: Rik van Riel <r...@redhat.com> Acked-by: Mel Gorman <mgor...@suse.de> Signed-off-by: Peter Zijlstra <pet...@infradead.org> Cc: Chegu Vinod <chegu_vi...@hp.com> Link: http://lkml.kernel.org/r/1390860228-21539-5-git-send-email-r...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Yang Shi <yang....@windriver.com> --- kernel/sched/fair.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 167c490..ccda061 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -885,6 +885,7 @@ struct numa_group { struct list_head task_list; struct rcu_head rcu; + nodemask_t active_nodes; unsigned long total_faults; unsigned long *faults_cpu; unsigned long faults[0]; @@ -918,6 +919,12 @@ static inline unsigned long group_faults(struct task_struct *p, int nid) p->numa_group->faults[task_faults_idx(nid, 1)]; } +static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) +{ + return group->faults_cpu[task_faults_idx(nid, 0)] + + group->faults_cpu[task_faults_idx(nid, 1)]; +} + /* * These return the fraction of accesses done by a particular task, or * task group, on a particular numa node. The group weight is given a @@ -1275,6 +1282,38 @@ static void numa_migrate_preferred(struct task_struct *p) } /* + * Find the nodes on which the workload is actively running. We do this by + * tracking the nodes from which NUMA hinting faults are triggered. This can + * be different from the set of nodes where the workload's memory is currently + * located. + * + * The bitmask is used to make smarter decisions on when to do NUMA page + * migrations, To prevent flip-flopping, and excessive page migrations, nodes + * are added when they cause over 6/16 of the maximum number of faults, but + * only removed when they drop below 3/16. + */ +static void update_numa_active_node_mask(struct numa_group *numa_group) +{ + unsigned long faults, max_faults = 0; + int nid; + + for_each_online_node(nid) { + faults = group_faults_cpu(numa_group, nid); + if (faults > max_faults) + max_faults = faults; + } + + for_each_online_node(nid) { + faults = group_faults_cpu(numa_group, nid); + if (!node_isset(nid, numa_group->active_nodes)) { + if (faults > max_faults * 6 / 16) + node_set(nid, numa_group->active_nodes); + } else if (faults < max_faults * 3 / 16) + node_clear(nid, numa_group->active_nodes); + } +} + +/* * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS * increments. The more local the fault statistics are, the higher the scan * period will be for the next scan window. If local/remote ratio is below @@ -1416,6 +1455,7 @@ static void task_numa_placement(struct task_struct *p) update_task_scan_period(p, fault_types[0], fault_types[1]); if (p->numa_group) { + update_numa_active_node_mask(p->numa_group); /* * If the preferred task and group nids are different, * iterate over the nodes again to find the best place. @@ -1478,6 +1518,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, /* Second half of the array tracks nids where faults happen */ grp->faults_cpu = grp->faults + 2 * nr_node_ids; + node_set(task_node(current), grp->active_nodes); + for (i = 0; i < 4*nr_node_ids; i++) grp->faults[i] = p->numa_faults_memory[i]; -- 2.0.2 -- _______________________________________________ linux-yocto mailing list linux-yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/linux-yocto
