From 2ffd8679c8e4ec226718bff58b50b226dd477015 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 21 Sep 2009 17:02:23 -0700 Subject: ksm: sysfs and defaults At present KSM is just a waste of space if you don't have CONFIG_SYSFS=y to provide the /sys/kernel/mm/ksm files to tune and activate it. Make KSM depend on SYSFS? Could do, but it might be better to provide some defaults so that KSM works out-of-the-box, ready for testers to madvise MADV_MERGEABLE, even without SYSFS. Though anyone serious is likely to want to retune the numbers to their taste once they have experience; and whether these settings ever reach 2.6.32 can be discussed along the way. Save 1kB from tiny kernels by #ifdef'ing the SYSFS side of it. Signed-off-by: Hugh Dickins Acked-by: Izik Eidus Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/ksm.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/mm/ksm.c b/mm/ksm.c index 92034eb47eba..3bd54ce9eb38 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -163,18 +163,18 @@ static unsigned long ksm_pages_unshared; static unsigned long ksm_rmap_items; /* Limit on the number of unswappable pages used */ -static unsigned long ksm_max_kernel_pages; +static unsigned long ksm_max_kernel_pages = 2000; /* Number of pages ksmd should scan in one batch */ -static unsigned int ksm_thread_pages_to_scan; +static unsigned int ksm_thread_pages_to_scan = 200; /* Milliseconds ksmd should sleep between batches */ -static unsigned int ksm_thread_sleep_millisecs; +static unsigned int ksm_thread_sleep_millisecs = 20; #define KSM_RUN_STOP 0 #define KSM_RUN_MERGE 1 #define KSM_RUN_UNMERGE 2 -static unsigned int ksm_run; +static unsigned int ksm_run = KSM_RUN_MERGE; static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait); static DEFINE_MUTEX(ksm_thread_mutex); @@ -506,6 +506,10 @@ static int unmerge_ksm_pages(struct vm_area_struct *vma, return err; } +#ifdef CONFIG_SYSFS +/* + * Only called through the sysfs control interface: + */ static int unmerge_and_remove_all_rmap_items(void) { struct mm_slot *mm_slot; @@ -563,6 +567,7 @@ error: spin_unlock(&ksm_mmlist_lock); return err; } +#endif /* CONFIG_SYSFS */ static u32 calc_checksum(struct page *page) { @@ -1454,6 +1459,11 @@ void __ksm_exit(struct mm_struct *mm) } } +#ifdef CONFIG_SYSFS +/* + * This all compiles without CONFIG_SYSFS, but is a waste of space. + */ + #define KSM_ATTR_RO(_name) \ static struct kobj_attribute _name##_attr = __ATTR_RO(_name) #define KSM_ATTR(_name) \ @@ -1636,6 +1646,7 @@ static struct attribute_group ksm_attr_group = { .attrs = ksm_attrs, .name = "ksm", }; +#endif /* CONFIG_SYSFS */ static int __init ksm_init(void) { @@ -1657,16 +1668,17 @@ static int __init ksm_init(void) goto out_free2; } +#ifdef CONFIG_SYSFS err = sysfs_create_group(mm_kobj, &ksm_attr_group); if (err) { printk(KERN_ERR "ksm: register sysfs failed\n"); - goto out_free3; + kthread_stop(ksm_thread); + goto out_free2; } +#endif /* CONFIG_SYSFS */ return 0; -out_free3: - kthread_stop(ksm_thread); out_free2: mm_slots_hash_free(); out_free1: -- cgit v1.2.1