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| author | Rik van Riel <riel@redhat.com> | 2013-10-07 11:29:08 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-10-09 12:40:36 +0200 |
| commit | 6fe6b2d6dabf392aceb3ad3a5e859b46a04465c6 (patch) | |
| tree | db4493950d94c418edcce093bd698e79ec1dca1a /mm | |
| parent | b795854b1fa70f6aee923ae5df74ff7afeaddcaa (diff) | |
| download | blackbird-obmc-linux-6fe6b2d6dabf392aceb3ad3a5e859b46a04465c6.tar.gz blackbird-obmc-linux-6fe6b2d6dabf392aceb3ad3a5e859b46a04465c6.zip | |
sched/numa: Do not migrate memory immediately after switching node
The load balancer can move tasks between nodes and does not take NUMA
locality into account. With automatic NUMA balancing this may result in the
tasks working set being migrated to the new node. However, as the fault
buffer will still store faults from the old node the schduler may decide to
reset the preferred node and migrate the task back resulting in more
migrations.
The ideal would be that the scheduler did not migrate tasks with a heavy
memory footprint but this may result nodes being overloaded. We could
also discard the fault information on task migration but this would still
cause all the tasks working set to be migrated. This patch simply avoids
migrating the memory for a short time after a task is migrated.
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/1381141781-10992-31-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mempolicy.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index aff1f1ed3dc5..196d8da2b657 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2378,6 +2378,18 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long last_nidpid = page_nidpid_xchg_last(page, this_nidpid); if (!nidpid_pid_unset(last_nidpid) && nidpid_to_nid(last_nidpid) != polnid) 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 (polnid != current->numa_preferred_nid && + !current->numa_migrate_seq) + goto out; +#endif } if (curnid != polnid) |
