On 2021/11/11 16:51, Huang, Ying wrote:
Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> writes:
For the worst case (MAX_NUMNODES=1024), the node_demotion structure can
consume 32k bytes, which appears too large, so we can change to allocate
node_demotion dynamically at initialization time. Meanwhile allocating
the target demotion nodes array dynamically to select a suitable size
according to the MAX_NUMNODES.
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 38 +++++++++++++++++++++++++++++---------
1 file changed, 29 insertions(+), 9 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 126e9e6..0145b38 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1152,10 +1152,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
#define DEFAULT_DEMOTION_TARGET_NODES 15
struct demotion_nodes {
unsigned short nr;
- short nodes[DEFAULT_DEMOTION_TARGET_NODES];
+ short nodes[];
};
-static struct demotion_nodes node_demotion[MAX_NUMNODES] __read_mostly;
+static struct demotion_nodes *node_demotion[MAX_NUMNODES] __read_mostly;
+static unsigned short target_nodes_max;
I think we can use something as below,
#if MAX_NUMNODES < DEFAULT_DEMOTION_TARGET_NODES
#define DEMOTION_TARGET_NODES (MAX_NUMNODES - 1)
#else
#define DEMOTION_TARGET_NODES DEFAULT_DEMOTION_TARGET_NODES
#endif
Yes, looks better.
static struct demotion_nodes *node_demotion;
Then we can allocate nr_node_ids * sizeof(struct demotion_nodes) for node_demotion.
Yeah, this is simple. The reason I want to declare the structure like
"struct demotion_nodes *node_demotion[MAX_NUMNODES]" is that, we can
validate the non-possible nodes which are invalid to demote memory, and
in case the node_demotion[nid] is failed to be allocated which can be
validated, though this is unlikely. However, I agree with you to keep
things simple now and can be merged into patch 1. Will do in next
version. Thanks.
