diff options
| -rw-r--r-- | Documentation/sysctl/vm.txt | 15 | ||||
| -rw-r--r-- | include/linux/compaction.h | 3 | ||||
| -rw-r--r-- | kernel/sysctl.c | 15 | ||||
| -rw-r--r-- | mm/compaction.c | 12 |
4 files changed, 44 insertions, 1 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 56dd29b97a91..5fdbb612aeb8 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/vm: - dirty_ratio - dirty_writeback_centisecs - drop_caches +- extfrag_threshold - hugepages_treat_as_movable - hugetlb_shm_group - laptop_mode @@ -149,6 +150,20 @@ user should run `sync' first. ============================================================== +extfrag_threshold + +This parameter affects whether the kernel will compact memory or direct +reclaim to satisfy a high-order allocation. /proc/extfrag_index shows what +the fragmentation index for each order is in each zone in the system. Values +tending towards 0 imply allocations would fail due to lack of memory, +values towards 1000 imply failures are due to fragmentation and -1 implies +that the allocation will succeed as long as watermarks are met. + +The kernel will not compact memory in a zone if the +fragmentation index is <= extfrag_threshold. The default value is 500. + +============================================================== + hugepages_treat_as_movable This parameter is only useful when kernelcore= is specified at boot time to diff --git a/include/linux/compaction.h b/include/linux/compaction.h index eed40ec4280b..3719325c6091 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -15,6 +15,9 @@ extern int sysctl_compact_memory; extern int sysctl_compaction_handler(struct ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos); +extern int sysctl_extfrag_threshold; +extern int sysctl_extfrag_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos); extern int fragmentation_index(struct zone *zone, unsigned int order); extern unsigned long try_to_compact_pages(struct zonelist *zonelist, diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 284f330d6a01..84ff5e75c084 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -263,6 +263,11 @@ static int min_sched_shares_ratelimit = 100000; /* 100 usec */ static int max_sched_shares_ratelimit = NSEC_PER_SEC; /* 1 second */ #endif +#ifdef CONFIG_COMPACTION +static int min_extfrag_threshold; +static int max_extfrag_threshold = 1000; +#endif + static struct ctl_table kern_table[] = { { .procname = "sched_child_runs_first", @@ -1130,6 +1135,16 @@ static struct ctl_table vm_table[] = { .mode = 0200, .proc_handler = sysctl_compaction_handler, }, + { + .procname = "extfrag_threshold", + .data = &sysctl_extfrag_threshold, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = sysctl_extfrag_handler, + .extra1 = &min_extfrag_threshold, + .extra2 = &max_extfrag_threshold, + }, + #endif /* CONFIG_COMPACTION */ { .procname = "min_free_kbytes", diff --git a/mm/compaction.c b/mm/compaction.c index 9583e193dc47..94cce51b0b35 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -433,6 +433,8 @@ static unsigned long compact_zone_order(struct zone *zone, return compact_zone(zone, &cc); } +int sysctl_extfrag_threshold = 500; + /** * try_to_compact_pages - Direct compact to satisfy a high-order allocation * @zonelist: The zonelist used for the current allocation @@ -491,7 +493,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist, * Only compact if a failure would be due to fragmentation. */ fragindex = fragmentation_index(zone, order); - if (fragindex >= 0 && fragindex <= 500) + if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) continue; if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) { @@ -572,6 +574,14 @@ int sysctl_compaction_handler(struct ctl_table *table, int write, return 0; } +int sysctl_extfrag_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos) +{ + proc_dointvec_minmax(table, write, buffer, length, ppos); + + return 0; +} + #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) ssize_t sysfs_compact_node(struct sys_device *dev, struct sysdev_attribute *attr, |