linux-kernel - [PATCH -V9 1/6] NUMA Balancing: add page promotion counter

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Date:   Fri,  8 Oct 2021 16:39:33 +0800
From:   Huang Ying <ying.huang@...el.com>
To:     linux-kernel@...r.kernel.org
Cc:     Huang Ying <ying.huang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Rik van Riel <riel@...riel.com>,
        Mel Gorman <mgorman@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>, Zi Yan <ziy@...dia.com>,
        Wei Xu <weixugc@...gle.com>, osalvador <osalvador@...e.de>,
        Shakeel Butt <shakeelb@...gle.com>, linux-mm@...ck.org
Subject: [PATCH -V9 1/6] NUMA Balancing: add page promotion counter

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.

Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Rik van Riel <riel@...riel.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Yang Shi <shy828301@...il.com>
Cc: Zi Yan <ziy@...dia.com>
Cc: Wei Xu <weixugc@...gle.com>
Cc: osalvador <osalvador@...e.de>
Cc: Shakeel Butt <shakeelb@...gle.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org
---
 include/linux/mmzone.h |  3 +++
 include/linux/node.h   |  5 +++++
 include/linux/vmstat.h |  2 ++
 mm/migrate.c           | 10 ++++++++--
 mm/vmstat.c            |  3 +++
 5 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6a1d79d84675..37ccd6158765 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -209,6 +209,9 @@ 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 8e5a29897936..26e96fcc66af 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/include/linux/vmstat.h b/include/linux/vmstat.h
index d6a6cf53b127..75c53b7d1539 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -112,9 +112,11 @@ static inline void vm_events_fold_cpu(int cpu)
 #ifdef CONFIG_NUMA_BALANCING
 #define count_vm_numa_event(x)     count_vm_event(x)
 #define count_vm_numa_events(x, y) count_vm_events(x, y)
+#define mod_node_balancing_page_state(n, i, v) mod_node_page_state(n, i, v)
 #else
 #define count_vm_numa_event(x) do {} while (0)
 #define count_vm_numa_events(x, y) do { (void)(y); } while (0)
+#define mod_node_balancing_page_state(n, i, v) do {} while (0)
 #endif /* CONFIG_NUMA_BALANCING */
 
 #ifdef CONFIG_DEBUG_TLBFLUSH
diff --git a/mm/migrate.c b/mm/migrate.c
index a6a7743ee98f..c3affc587902 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2148,6 +2148,7 @@ 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;
@@ -2186,7 +2187,8 @@ 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);
@@ -2195,8 +2197,12 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
 			putback_lru_page(page);
 		}
 		isolated = 0;
-	} else
+	} else {
 		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_pages);
+		if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
+			mod_node_balancing_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 8ce2620344b2..fff0ec94d795 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1236,6 +1236,9 @@ 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