path: root/mm/Kconfig
diff options
authorHugh Dickins <>2009-10-07 16:32:22 -0700
committerLinus Torvalds <>2009-10-08 07:36:38 -0700
commitc73602ad31cdcf7e6651f43d12f65b5b9b825b6f (patch)
treee9af7ebc13854e03e9ea0ee1c4e7e00475506fa7 /mm/Kconfig
parent0eca52a92735f43462165efe00a7e394345fb38e (diff)
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 <> Cc: Izik Eidus <> Cc: Andrea Arcangeli <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/Kconfig')
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index edd300aca17..57963c6063d 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).
int "Low address space to protect from user allocation"