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| author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-10-07 16:32:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-10-08 07:36:38 -0700 |
| commit | c73602ad31cdcf7e6651f43d12f65b5b9b825b6f (patch) | |
| tree | e9af7ebc13854e03e9ea0ee1c4e7e00475506fa7 /mm | |
| parent | 0eca52a92735f43462165efe00a7e394345fb38e (diff) | |
| download | lwn-c73602ad31cdcf7e6651f43d12f65b5b9b825b6f.tar.gz lwn-c73602ad31cdcf7e6651f43d12f65b5b9b825b6f.zip | |
ksm: more on default values
Adjust the max_kernel_pages default to a quarter of totalram_pages,
instead of nr_free_buffer_pages() / 4: the KSM pages themselves come from
highmem, and even on a 16GB PAE machine, 4GB of KSM pages would only be
pinning 32MB of lowmem with their rmap_items, so no need for the more
obscure calculation (nor for its own special init function).
There is no way for the user to switch KSM on if CONFIG_SYSFS is not
enabled, so in that case default run to KSM_RUN_MERGE.
Update KSM Documentation and Kconfig to reflect the new defaults.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig | 4 | ||||
| -rw-r--r-- | mm/ksm.c | 10 |
2 files changed, 7 insertions, 7 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index edd300aca173..57963c6063d1 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -224,7 +224,9 @@ config KSM the many instances by a single resident page with that content, so saving memory until one or another app needs to modify the content. Recommended for use with KVM, or with other duplicative applications. - See Documentation/vm/ksm.txt for more information. + See Documentation/vm/ksm.txt for more information: KSM is inactive + until a program has madvised that an area is MADV_MERGEABLE, and + root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). config DEFAULT_MMAP_MIN_ADDR int "Low address space to protect from user allocation" @@ -184,11 +184,6 @@ static DEFINE_SPINLOCK(ksm_mmlist_lock); sizeof(struct __struct), __alignof__(struct __struct),\ (__flags), NULL) -static void __init ksm_init_max_kernel_pages(void) -{ - ksm_max_kernel_pages = nr_free_buffer_pages() / 4; -} - static int __init ksm_slab_init(void) { rmap_item_cache = KSM_KMEM_CACHE(rmap_item, 0); @@ -1673,7 +1668,7 @@ static int __init ksm_init(void) struct task_struct *ksm_thread; int err; - ksm_init_max_kernel_pages(); + ksm_max_kernel_pages = totalram_pages / 4; err = ksm_slab_init(); if (err) @@ -1697,6 +1692,9 @@ static int __init ksm_init(void) kthread_stop(ksm_thread); goto out_free2; } +#else + ksm_run = KSM_RUN_MERGE; /* no way for user to start it */ + #endif /* CONFIG_SYSFS */ return 0; |