Commit 2739d3ee authored by Rik van Riel's avatar Rik van Riel Committed by Ingo Molnar

sched/numa: Retry task_numa_migrate() periodically

Short spikes of CPU load can lead to a task being migrated
away from its preferred node for temporary reasons.

It is important that the task is migrated back to where it
belongs, in order to avoid migrating too much memory to its
new location, and generally disturbing a task's NUMA location.

This patch fixes NUMA placement for 4 specjbb instances on
a 4 node system. Without this patch, things take longer to
converge, and processes are not always completely on their
own node.
Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarMel 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: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-64-git-send-email-mgorman@suse.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 989348b5
...@@ -1259,18 +1259,19 @@ static int task_numa_migrate(struct task_struct *p) ...@@ -1259,18 +1259,19 @@ static int task_numa_migrate(struct task_struct *p)
/* Attempt to migrate a task to a CPU on the preferred node. */ /* Attempt to migrate a task to a CPU on the preferred node. */
static void numa_migrate_preferred(struct task_struct *p) static void numa_migrate_preferred(struct task_struct *p)
{ {
/* Success if task is already running on preferred CPU */ /* This task has no NUMA fault statistics yet */
p->numa_migrate_retry = 0; if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults))
if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid)
return; return;
/* This task has no NUMA fault statistics yet */ /* Periodically retry migrating the task to the preferred node */
if (unlikely(p->numa_preferred_nid == -1)) p->numa_migrate_retry = jiffies + HZ;
/* Success if task is already running on preferred CPU */
if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid)
return; return;
/* Otherwise, try migrate to a CPU on the preferred node */ /* Otherwise, try migrate to a CPU on the preferred node */
if (task_numa_migrate(p) != 0) task_numa_migrate(p);
p->numa_migrate_retry = jiffies + HZ*5;
} }
/* /*
...@@ -1629,8 +1630,11 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags) ...@@ -1629,8 +1630,11 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
task_numa_placement(p); task_numa_placement(p);
/* Retry task to preferred node migration if it previously failed */ /*
if (p->numa_migrate_retry && time_after(jiffies, p->numa_migrate_retry)) * Retry task to preferred node migration periodically, in case it
* case it previously failed, or the scheduler moved us.
*/
if (time_after(jiffies, p->numa_migrate_retry))
numa_migrate_preferred(p); numa_migrate_preferred(p);
if (migrated) if (migrated)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment