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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-10-07 16:32:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-10-08 07:36:38 -0700
commitc73602ad31cdcf7e6651f43d12f65b5b9b825b6f (patch)
treee9af7ebc13854e03e9ea0ee1c4e7e00475506fa7 /mm
parent0eca52a92735f43462165efe00a7e394345fb38e (diff)
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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/Kconfig4
-rw-r--r--mm/ksm.c10
2 files changed, 7 insertions, 7 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index edd300a..57963c6 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"
diff --git a/mm/ksm.c b/mm/ksm.c
index f7edac3..bef1af4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -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;