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 <hugh.dickins@tiscali.co.uk>
Acked-by: 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>
diff --git a/mm/ksm.c b/mm/ksm.c
index 92034eb..3bd54ce 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -163,18 +163,18 @@
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 @@
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 @@
spin_unlock(&ksm_mmlist_lock);
return err;
}
+#endif /* CONFIG_SYSFS */
static u32 calc_checksum(struct page *page)
{
@@ -1454,6 +1459,11 @@
}
}
+#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 @@
.attrs = ksm_attrs,
.name = "ksm",
};
+#endif /* CONFIG_SYSFS */
static int __init ksm_init(void)
{
@@ -1657,16 +1668,17 @@
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: