diff options
| -rw-r--r-- | include/linux/mm.h | 2 | ||||
| -rw-r--r-- | include/linux/mman.h | 4 | ||||
| -rw-r--r-- | kernel/sysctl.c | 2 | ||||
| -rw-r--r-- | mm/mm_init.c | 22 | ||||
| -rw-r--r-- | mm/util.c | 41 |
5 files changed, 64 insertions, 7 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 2830f1c0fdc3..1c3470550395 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -206,6 +206,8 @@ int overcommit_ratio_handler(struct ctl_table *, int, void *, size_t *, loff_t *); int overcommit_kbytes_handler(struct ctl_table *, int, void *, size_t *, loff_t *); +int overcommit_policy_handler(struct ctl_table *, int, void *, size_t *, + loff_t *); #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n)) diff --git a/include/linux/mman.h b/include/linux/mman.h index 4b08e9c9c538..6f34c33075f9 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -57,8 +57,12 @@ extern struct percpu_counter vm_committed_as; #ifdef CONFIG_SMP extern s32 vm_committed_as_batch; +extern void mm_compute_batch(int overcommit_policy); #else #define vm_committed_as_batch 0 +static inline void mm_compute_batch(int overcommit_policy) +{ +} #endif unsigned long vm_memory_committed(void); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 1b4d2dc270a5..f785de3caac0 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2671,7 +2671,7 @@ static struct ctl_table vm_table[] = { .data = &sysctl_overcommit_memory, .maxlen = sizeof(sysctl_overcommit_memory), .mode = 0644, - .proc_handler = proc_dointvec_minmax, + .proc_handler = overcommit_policy_handler, .extra1 = SYSCTL_ZERO, .extra2 = &two, }, diff --git a/mm/mm_init.c b/mm/mm_init.c index 435e5f794b3b..b06a30fbedff 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -13,6 +13,7 @@ #include <linux/memory.h> #include <linux/notifier.h> #include <linux/sched.h> +#include <linux/mman.h> #include "internal.h" #ifdef CONFIG_DEBUG_MEMORY_INIT @@ -144,14 +145,23 @@ EXPORT_SYMBOL_GPL(mm_kobj); #ifdef CONFIG_SMP s32 vm_committed_as_batch = 32; -static void __meminit mm_compute_batch(void) +void mm_compute_batch(int overcommit_policy) { u64 memsized_batch; s32 nr = num_present_cpus(); s32 batch = max_t(s32, nr*2, 32); - - /* batch size set to 0.4% of (total memory/#cpus), or max int32 */ - memsized_batch = min_t(u64, (totalram_pages()/nr)/256, 0x7fffffff); + unsigned long ram_pages = totalram_pages(); + + /* + * For policy OVERCOMMIT_NEVER, set batch size to 0.4% of + * (total memory/#cpus), and lift it to 25% for other policies + * to easy the possible lock contention for percpu_counter + * vm_committed_as, while the max limit is INT_MAX + */ + if (overcommit_policy == OVERCOMMIT_NEVER) + memsized_batch = min_t(u64, ram_pages/nr/256, INT_MAX); + else + memsized_batch = min_t(u64, ram_pages/nr/4, INT_MAX); vm_committed_as_batch = max_t(s32, memsized_batch, batch); } @@ -162,7 +172,7 @@ static int __meminit mm_compute_batch_notifier(struct notifier_block *self, switch (action) { case MEM_ONLINE: case MEM_OFFLINE: - mm_compute_batch(); + mm_compute_batch(sysctl_overcommit_memory); default: break; } @@ -176,7 +186,7 @@ static struct notifier_block compute_batch_nb __meminitdata = { static int __init mm_compute_batch_init(void) { - mm_compute_batch(); + mm_compute_batch(sysctl_overcommit_memory); register_hotmemory_notifier(&compute_batch_nb); return 0; diff --git a/mm/util.c b/mm/util.c index 1c9d097d7e48..8d6280c05238 100644 --- a/mm/util.c +++ b/mm/util.c @@ -746,6 +746,47 @@ int overcommit_ratio_handler(struct ctl_table *table, int write, void *buffer, return ret; } +static void sync_overcommit_as(struct work_struct *dummy) +{ + percpu_counter_sync(&vm_committed_as); +} + +int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos) +{ + struct ctl_table t; + int new_policy; + int ret; + + /* + * The deviation of sync_overcommit_as could be big with loose policy + * like OVERCOMMIT_ALWAYS/OVERCOMMIT_GUESS. When changing policy to + * strict OVERCOMMIT_NEVER, we need to reduce the deviation to comply + * with the strict "NEVER", and to avoid possible race condtion (even + * though user usually won't too frequently do the switching to policy + * OVERCOMMIT_NEVER), the switch is done in the following order: + * 1. changing the batch + * 2. sync percpu count on each CPU + * 3. switch the policy + */ + if (write) { + t = *table; + t.data = &new_policy; + ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); + if (ret) + return ret; + + mm_compute_batch(new_policy); + if (new_policy == OVERCOMMIT_NEVER) + schedule_on_each_cpu(sync_overcommit_as); + sysctl_overcommit_memory = new_policy; + } else { + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + } + + return ret; +} + int overcommit_kbytes_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { |