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ksm: more on default values

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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>
This commit is contained in:
Hugh Dickins
2009-10-07 16:32:22 -07:00
committed by Linus Torvalds
parent 0eca52a927
commit c73602ad31
3 changed files with 14 additions and 13 deletions
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10
mm/ksm.c
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@@ -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;