mm: numa: Revert temporarily disabling of NUMA migration

With the scan rate code working (at least for multi-instance specjbb),
the large hammer that is "sched: Do not migrate memory immediately after
switching node" can be replaced with something smarter. Revert temporarily
migration disabling and all traces of numa_migrate_seq.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-61-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2292f6c1596f33bd7500f89931e822d19b4f4304..d24f70ffddeed3b637537d40a19c30657925e630 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1340,7 +1340,6 @@ struct task_struct {
 #endif
 #ifdef CONFIG_NUMA_BALANCING
        int numa_scan_seq;
-       int numa_migrate_seq;
        unsigned int numa_scan_period;
        unsigned int numa_scan_period_max;
        unsigned long numa_migrate_retry;

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 89c5ae836f66627d584535863ce167c93e97e8ec..0c3feebcf1128b68a742a3b6c6aee9af5a6397de 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1731,7 +1731,6 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
 
        p->node_stamp = 0ULL;
        p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
-       p->numa_migrate_seq = 1;
        p->numa_scan_period = sysctl_numa_balancing_scan_delay;
        p->numa_work.next = &p->numa_work;
        p->numa_faults = NULL;
@@ -4488,7 +4487,6 @@ void sched_setnuma(struct task_struct *p, int nid)
                p->sched_class->put_prev_task(rq, p);
 
        p->numa_preferred_nid = nid;
-       p->numa_migrate_seq = 1;
 
        if (running)
                p->sched_class->set_curr_task(rq);

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index da6fa22be000f77cef7298ea289d591b59b48c38..8454c38b1b12fb05d7c20f5309590558d85bb34b 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1261,16 +1261,8 @@ static void numa_migrate_preferred(struct task_struct *p)
 {
        /* Success if task is already running on preferred CPU */
        p->numa_migrate_retry = 0;
-       if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid) {
-               /*
-                * If migration is temporarily disabled due to a task migration
-                * then re-enable it now as the task is running on its
-                * preferred node and memory should migrate locally
-                */
-               if (!p->numa_migrate_seq)
-                       p->numa_migrate_seq++;
+       if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid)
                return;
-       }
 
        /* This task has no NUMA fault statistics yet */
        if (unlikely(p->numa_preferred_nid == -1))
@@ -1367,7 +1359,6 @@ static void task_numa_placement(struct task_struct *p)
        if (p->numa_scan_seq == seq)
                return;
        p->numa_scan_seq = seq;
-       p->numa_migrate_seq++;
        p->numa_scan_period_max = task_scan_max(p);
 
        /* If the task is part of a group prevent parallel updates to group stats */
@@ -4730,20 +4721,6 @@ static void move_task(struct task_struct *p, struct lb_env *env)
        set_task_cpu(p, env->dst_cpu);
        activate_task(env->dst_rq, p, 0);
        check_preempt_curr(env->dst_rq, p, 0);
-#ifdef CONFIG_NUMA_BALANCING
-       if (p->numa_preferred_nid != -1) {
-               int src_nid = cpu_to_node(env->src_cpu);
-               int dst_nid = cpu_to_node(env->dst_cpu);
-
-               /*
-                * If the load balancer has moved the task then limit
-                * migrations from taking place in the short term in
-                * case this is a short-lived migration.
-                */
-               if (src_nid != dst_nid && dst_nid != p->numa_preferred_nid)
-                       p->numa_migrate_seq = 0;
-       }
-#endif
 }
 
 /*

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index a5867ef24bdad75dbb7cedfc10a6a4fd8468e738..2929c24c22b74b9c9ed2bd71465d0c38380a0bfb 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2404,18 +2404,6 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
                last_cpupid = page_cpupid_xchg_last(page, this_cpupid);
                if (!cpupid_pid_unset(last_cpupid) && cpupid_to_nid(last_cpupid) != thisnid)
                        goto out;
-
-#ifdef CONFIG_NUMA_BALANCING
-               /*
-                * If the scheduler has just moved us away from our
-                * preferred node, do not bother migrating pages yet.
-                * This way a short and temporary process migration will
-                * not cause excessive memory migration.
-                */
-               if (thisnid != current->numa_preferred_nid &&
-                               !current->numa_migrate_seq)
-                       goto out;
-#endif
        }
 
        if (curnid != polnid)