diff options
| -rw-r--r-- | mm/vmstat.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index d3e0fa1..23a5899 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -16,6 +16,7 @@ #include <linux/cpu.h> #include <linux/vmstat.h> #include <linux/sched.h> +#include <linux/math64.h> #ifdef CONFIG_VM_EVENT_COUNTERS DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}}; @@ -420,6 +421,33 @@ static void fill_contig_page_info(struct zone *zone, (order - suitable_order); } } + +/* + * A fragmentation index only makes sense if an allocation of a requested + * size would fail. If that is true, the fragmentation index indicates + * whether external fragmentation or a lack of memory was the problem. + * The value can be used to determine if page reclaim or compaction + * should be used + */ +int fragmentation_index(unsigned int order, struct contig_page_info *info) +{ + unsigned long requested = 1UL << order; + + if (!info->free_blocks_total) + return 0; + + /* Fragmentation index only makes sense when a request would fail */ + if (info->free_blocks_suitable) + return -1000; + + /* + * Index is between 0 and 1 so return within 3 decimal places + * + * 0 => allocation would fail due to lack of memory + * 1 => allocation would fail due to fragmentation + */ + return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total); +} #endif #if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION) @@ -1087,6 +1115,58 @@ static const struct file_operations unusable_file_ops = { .release = seq_release, }; +static void extfrag_show_print(struct seq_file *m, + pg_data_t *pgdat, struct zone *zone) +{ + unsigned int order; + int index; + + /* Alloc on stack as interrupts are disabled for zone walk */ + struct contig_page_info info; + + seq_printf(m, "Node %d, zone %8s ", + pgdat->node_id, + zone->name); + for (order = 0; order < MAX_ORDER; ++order) { + fill_contig_page_info(zone, order, &info); + index = fragmentation_index(order, &info); + seq_printf(m, "%d.%03d ", index / 1000, index % 1000); + } + + seq_putc(m, '\n'); +} + +/* + * Display fragmentation index for orders that allocations would fail for + */ +static int extfrag_show(struct seq_file *m, void *arg) +{ + pg_data_t *pgdat = (pg_data_t *)arg; + + walk_zones_in_node(m, pgdat, extfrag_show_print); + + return 0; +} + +static const struct seq_operations extfrag_op = { + .start = frag_start, + .next = frag_next, + .stop = frag_stop, + .show = extfrag_show, +}; + +static int extfrag_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &extfrag_op); +} + +static const struct file_operations extfrag_file_ops = { + .open = extfrag_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + static int __init extfrag_debug_init(void) { extfrag_debug_root = debugfs_create_dir("extfrag", NULL); @@ -1097,6 +1177,10 @@ static int __init extfrag_debug_init(void) extfrag_debug_root, NULL, &unusable_file_ops)) return -ENOMEM; + if (!debugfs_create_file("extfrag_index", 0444, + extfrag_debug_root, NULL, &extfrag_file_ops)) + return -ENOMEM; + return 0; } |
