ksm: change ksm nice level to be 5

ksm should try not to disturb other tasks as much as possible.
Signed-off-by: NIzik Eidus <ieidus@redhat.com>
Cc: Chris Wright <chrisw@redhat.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/ksm.c

@@ -1263,7 +1263,7 @@ static void ksm_do_scan(unsigned int scan_npages)
 
 static int ksm_scan_thread(void *nothing)
 {
-	set_user_nice(current, 0);
+	set_user_nice(current, 5);
 
 	while (!kthread_should_stop()) {
 		if (ksm_run & KSM_RUN_MERGE) {