sched/numa: Remove the numa_balancing_scan_period_reset sysctl

With scan rate adaptions based on whether the workload has properly
converged or not there should be no need for the scan period reset
hammer. Get rid of it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
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/1381141781-10992-60-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index d48bca45b6f2bf0e415f0a56b4b84b802cfcd948..84f17800f8b582787683c9d8252cbe1bc46e81ab 100644 (file)
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -374,15 +374,13 @@ guarantee. If the target workload is already bound to NUMA nodes then this
 feature should be disabled. Otherwise, if the system overhead from the
 feature is too high then the rate the kernel samples for NUMA hinting
 faults may be controlled by the numa_balancing_scan_period_min_ms,
-numa_balancing_scan_delay_ms, numa_balancing_scan_period_reset,
-numa_balancing_scan_period_max_ms, numa_balancing_scan_size_mb and
-numa_balancing_settle_count sysctls.
+numa_balancing_scan_delay_ms, numa_balancing_scan_period_max_ms,
+numa_balancing_scan_size_mb and numa_balancing_settle_count sysctls.
 
 ==============================================================
 
 numa_balancing_scan_period_min_ms, numa_balancing_scan_delay_ms,
-numa_balancing_scan_period_max_ms, numa_balancing_scan_period_reset,
-numa_balancing_scan_size_mb
+numa_balancing_scan_period_max_ms, numa_balancing_scan_size_mb
 
 Automatic NUMA balancing scans tasks address space and unmaps pages to
 detect if pages are properly placed or if the data should be migrated to a
@@ -418,9 +416,6 @@ rate for each task.
 numa_balancing_scan_size_mb is how many megabytes worth of pages are
 scanned for a given scan.
 
-numa_balancing_scan_period_reset is a blunt instrument that controls how
-often a tasks scan delay is reset to detect sudden changes in task behaviour.
-
 numa_balancing_settle_count is how many scan periods must complete before
 the schedule balancer stops pushing the task towards a preferred node. This
 gives the scheduler a chance to place the task on an alternative node if the

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index a30f9ca66557a71f22a4eae3f1f8bcefbfdc546f..a3198e5aaf4e4dac55a70caae5669e8ab84906e3 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -420,9 +420,6 @@ struct mm_struct {
         */
        unsigned long numa_next_scan;
 
-       /* numa_next_reset is when the PTE scanner period will be reset */
-       unsigned long numa_next_reset;
-
        /* Restart point for scanning and setting pte_numa */
        unsigned long numa_scan_offset;
 

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index bf8086b2506e807d9b3c97679f0917d8d5944a96..10d16c4fbe89e45e157e173a98607d8e315c0f42 100644 (file)
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -47,7 +47,6 @@ extern enum sched_tunable_scaling sysctl_sched_tunable_scaling;
 extern unsigned int sysctl_numa_balancing_scan_delay;
 extern unsigned int sysctl_numa_balancing_scan_period_min;
 extern unsigned int sysctl_numa_balancing_scan_period_max;
-extern unsigned int sysctl_numa_balancing_scan_period_reset;
 extern unsigned int sysctl_numa_balancing_scan_size;
 extern unsigned int sysctl_numa_balancing_settle_count;
 

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8cfd51f6224119b0a25dd8d4ead8bdeb075c8dae..89c5ae836f66627d584535863ce167c93e97e8ec 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1721,7 +1721,6 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
 #ifdef CONFIG_NUMA_BALANCING
        if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
                p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
-               p->mm->numa_next_reset = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
                p->mm->numa_scan_seq = 0;
        }
 

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 66237ff8b01ebbff1a71424fb8eacc421466e451..da6fa22be000f77cef7298ea289d591b59b48c38 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -826,7 +826,6 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  */
 unsigned int sysctl_numa_balancing_scan_period_min = 1000;
 unsigned int sysctl_numa_balancing_scan_period_max = 60000;
-unsigned int sysctl_numa_balancing_scan_period_reset = 60000;
 
 /* Portion of address space to scan in MB */
 unsigned int sysctl_numa_balancing_scan_size = 256;
@@ -1685,24 +1684,9 @@ void task_numa_work(struct callback_head *work)
        if (p->flags & PF_EXITING)
                return;
 
-       if (!mm->numa_next_reset || !mm->numa_next_scan) {
+       if (!mm->numa_next_scan) {
                mm->numa_next_scan = now +
                        msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
-               mm->numa_next_reset = now +
-                       msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
-       }
-
-       /*
-        * Reset the scan period if enough time has gone by. Objective is that
-        * scanning will be reduced if pages are properly placed. As tasks
-        * can enter different phases this needs to be re-examined. Lacking
-        * proper tracking of reference behaviour, this blunt hammer is used.
-        */
-       migrate = mm->numa_next_reset;
-       if (time_after(now, migrate)) {
-               p->numa_scan_period = task_scan_min(p);
-               next_scan = now + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
-               xchg(&mm->numa_next_reset, next_scan);
        }
 
        /*

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 42f616a74f40d8ce857d284262fdeefc12188d63..e509b90a8002bad223a0d9314d953c505d7a1d91 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -370,13 +370,6 @@ static struct ctl_table kern_table[] = {
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
        },
-       {
-               .procname       = "numa_balancing_scan_period_reset",
-               .data           = &sysctl_numa_balancing_scan_period_reset,
-               .maxlen         = sizeof(unsigned int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec,
-       },
        {
                .procname       = "numa_balancing_scan_period_max_ms",
                .data           = &sysctl_numa_balancing_scan_period_max,