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authorMel Gorman <mgorman@suse.de>2012-11-14 21:41:46 +0000
committerMel Gorman <mgorman@suse.de>2012-12-11 14:42:50 +0000
commita8f6077213d285ca08dbf6d4a67470787388138b (patch)
tree1ce0c66b221a97e485d513552c75d29fe84b74bd
parent8177a420ed7c16c171ed3c3aec5b0676db38c247 (diff)
downloadop-kernel-dev-a8f6077213d285ca08dbf6d4a67470787388138b.zip
op-kernel-dev-a8f6077213d285ca08dbf6d4a67470787388138b.tar.gz
mm: numa: Rate limit the amount of memory that is migrated between nodes
NOTE: This is very heavily based on similar logic in autonuma. It should be signed off by Andrea but because there was no standalone patch and it's sufficiently different from what he did that the signed-off is omitted. Will be added back if requested. If a large number of pages are misplaced then the memory bus can be saturated just migrating pages between nodes. This patch rate-limits the amount of memory that can be migrating between nodes. Signed-off-by: Mel Gorman <mgorman@suse.de>
-rw-r--r--mm/migrate.c30
1 files changed, 29 insertions, 1 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 23bba5d..4b8267f 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1461,12 +1461,21 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
}
/*
+ * page migration rate limiting control.
+ * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs
+ * window of time. Default here says do not migrate more than 1280M per second.
+ */
+static unsigned int migrate_interval_millisecs __read_mostly = 100;
+static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT);
+
+/*
* Attempt to migrate a misplaced page to the specified destination
* node. Caller is expected to have an elevated reference count on
* the page that will be dropped by this function before returning.
*/
int migrate_misplaced_page(struct page *page, int node)
{
+ pg_data_t *pgdat = NODE_DATA(node);
int isolated = 0;
LIST_HEAD(migratepages);
@@ -1479,8 +1488,27 @@ int migrate_misplaced_page(struct page *page, int node)
goto out;
}
+ /*
+ * Rate-limit the amount of data that is being migrated to a node.
+ * Optimal placement is no good if the memory bus is saturated and
+ * all the time is being spent migrating!
+ */
+ spin_lock(&pgdat->numabalancing_migrate_lock);
+ if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) {
+ pgdat->numabalancing_migrate_nr_pages = 0;
+ pgdat->numabalancing_migrate_next_window = jiffies +
+ msecs_to_jiffies(migrate_interval_millisecs);
+ }
+ if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) {
+ spin_unlock(&pgdat->numabalancing_migrate_lock);
+ put_page(page);
+ goto out;
+ }
+ pgdat->numabalancing_migrate_nr_pages++;
+ spin_unlock(&pgdat->numabalancing_migrate_lock);
+
/* Avoid migrating to a node that is nearly full */
- if (migrate_balanced_pgdat(NODE_DATA(node), 1)) {
+ if (migrate_balanced_pgdat(pgdat, 1)) {
int page_lru;
if (isolate_lru_page(page)) {
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