diff options
| -rw-r--r-- | mm/page_alloc.c | 78 |
1 files changed, 20 insertions, 58 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index eac31a6059c0..bfb73e025e02 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3614,68 +3614,30 @@ static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes) zonelist->_zonerefs[pos].zone_idx = 0; } +#if defined(CONFIG_64BIT) +/* + * Devices that require DMA32/DMA are relatively rare and do not justify a + * penalty to every machine in case the specialised case applies. Default + * to Node-ordering on 64-bit NUMA machines + */ +static int default_zonelist_order(void) +{ + return ZONELIST_ORDER_NODE; +} +#else +/* + * On 32-bit, the Normal zone needs to be preserved for allocations accessible + * by the kernel. If processes running on node 0 deplete the low memory zone + * then reclaim will occur more frequency increasing stalls and potentially + * be easier to OOM if a large percentage of the zone is under writeback or + * dirty. The problem is significantly worse if CONFIG_HIGHPTE is not set. + * Hence, default to zone ordering on 32-bit. + */ static int default_zonelist_order(void) { - int nid, zone_type; - unsigned long low_kmem_size, total_size; - struct zone *z; - int average_size; - /* - * ZONE_DMA and ZONE_DMA32 can be very small area in the system. - * If they are really small and used heavily, the system can fall - * into OOM very easily. - * This function detect ZONE_DMA/DMA32 size and configures zone order. - */ - /* Is there ZONE_NORMAL ? (ex. ppc has only DMA zone..) */ - low_kmem_size = 0; - total_size = 0; - for_each_online_node(nid) { - for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) { - z = &NODE_DATA(nid)->node_zones[zone_type]; - if (populated_zone(z)) { - if (zone_type < ZONE_NORMAL) - low_kmem_size += z->managed_pages; - total_size += z->managed_pages; - } else if (zone_type == ZONE_NORMAL) { - /* - * If any node has only lowmem, then node order - * is preferred to allow kernel allocations - * locally; otherwise, they can easily infringe - * on other nodes when there is an abundance of - * lowmem available to allocate from. - */ - return ZONELIST_ORDER_NODE; - } - } - } - if (!low_kmem_size || /* there are no DMA area. */ - low_kmem_size > total_size/2) /* DMA/DMA32 is big. */ - return ZONELIST_ORDER_NODE; - /* - * look into each node's config. - * If there is a node whose DMA/DMA32 memory is very big area on - * local memory, NODE_ORDER may be suitable. - */ - average_size = total_size / - (nodes_weight(node_states[N_MEMORY]) + 1); - for_each_online_node(nid) { - low_kmem_size = 0; - total_size = 0; - for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) { - z = &NODE_DATA(nid)->node_zones[zone_type]; - if (populated_zone(z)) { - if (zone_type < ZONE_NORMAL) - low_kmem_size += z->present_pages; - total_size += z->present_pages; - } - } - if (low_kmem_size && - total_size > average_size && /* ignore small node */ - low_kmem_size > total_size * 70/100) - return ZONELIST_ORDER_NODE; - } return ZONELIST_ORDER_ZONE; } +#endif /* CONFIG_64BIT */ static void set_zonelist_order(void) { |