On Mon, Nov 15, 2021 at 5:36 PM Huang Ying <ying.huang@xxxxxxxxx> wrote:
>
> In a system with multiple memory types, e.g. DRAM and PMEM, the CPU
> and DRAM in one socket will be put in one NUMA node as before, while
> the PMEM will be put in another NUMA node as described in the
> description of the commit c221c0b0308f ("device-dax: "Hotplug"
> persistent memory for use like normal RAM"). So, the NUMA balancing
> mechanism will identify all PMEM accesses as remote access and try to
> promote the PMEM pages to DRAM.
>
> To distinguish the number of the inter-type promoted pages from that
> of the inter-socket migrated pages. A new vmstat count is added. The
> counter is per-node (count in the target node). So this can be used
> to identify promotion imbalance among the NUMA nodes.
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Yang Shi <shy828301@xxxxxxxxx>
> Cc: Zi Yan <ziy@xxxxxxxxxx>
> Cc: Wei Xu <weixugc@xxxxxxxxxx>
> Cc: osalvador <osalvador@xxxxxxx>
> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx
> ---
> include/linux/mmzone.h | 3 +++
> include/linux/node.h | 5 +++++
> mm/migrate.c | 13 ++++++++++---
> mm/vmstat.c | 3 +++
> 4 files changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 58e744b78c2c..eda6d2f09d77 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -210,6 +210,9 @@ enum node_stat_item {
> NR_PAGETABLE, /* used for pagetables */
> #ifdef CONFIG_SWAP
> NR_SWAPCACHE,
> +#endif
> +#ifdef CONFIG_NUMA_BALANCING
> + PGPROMOTE_SUCCESS, /* promote successfully */
> #endif
> NR_VM_NODE_STAT_ITEMS
> };
> diff --git a/include/linux/node.h b/include/linux/node.h
> index bb21fd631b16..81bbf1c0afd3 100644
> --- a/include/linux/node.h
> +++ b/include/linux/node.h
> @@ -181,4 +181,9 @@ static inline void register_hugetlbfs_with_node(node_registration_func_t reg,
>
> #define to_node(device) container_of(device, struct node, dev)
>
> +static inline bool node_is_toptier(int node)
> +{
> + return node_state(node, N_CPU);
> +}
> +
> #endif /* _LINUX_NODE_H_ */
> diff --git a/mm/migrate.c b/mm/migrate.c
> index cf25b00f03c8..b7c27abb0e5c 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2141,6 +2141,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
> pg_data_t *pgdat = NODE_DATA(node);
> int isolated;
> int nr_remaining;
> + int nr_succeeded;
> LIST_HEAD(migratepages);
> new_page_t *new;
> bool compound;
> @@ -2179,7 +2180,8 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
>
> list_add(&page->lru, &migratepages);
> nr_remaining = migrate_pages(&migratepages, *new, NULL, node,
> - MIGRATE_ASYNC, MR_NUMA_MISPLACED, NULL);
> + MIGRATE_ASYNC, MR_NUMA_MISPLACED,
> + &nr_succeeded);
> if (nr_remaining) {
> if (!list_empty(&migratepages)) {
> list_del(&page->lru);
> @@ -2188,8 +2190,13 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
> putback_lru_page(page);
> }
> isolated = 0;
> - } else
> - count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_pages);
> + }
> + if (nr_succeeded) {
> + count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
> + if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
> + mod_node_page_state(NODE_DATA(node), PGPROMOTE_SUCCESS,
> + nr_succeeded);
> + }
> BUG_ON(!list_empty(&migratepages));
> return isolated;
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index d701c335628c..53a6e92b1efb 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1242,6 +1242,9 @@ const char * const vmstat_text[] = {
> #ifdef CONFIG_SWAP
> "nr_swapcached",
> #endif
> +#ifdef CONFIG_NUMA_BALANCING
> + "pgpromote_success",
> +#endif
>
> /* enum writeback_stat_item counters */
> "nr_dirty_threshold",
> --
> 2.30.2
>
