linux-kernel - Re: [PATCH -V10 1/6] NUMA Balancing: add page promotion counter

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Date:   Wed, 17 Nov 2021 16:15:32 -0800
From:   Yang Shi <shy828301@...il.com>
To:     Huang Ying <ying.huang@...el.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Mel Gorman <mgorman@...e.de>, Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Feng Tang <feng.tang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Zi Yan <ziy@...dia.com>, Wei Xu <weixugc@...gle.com>,
        osalvador <osalvador@...e.de>, Shakeel Butt <shakeelb@...gle.com>
Subject: Re: [PATCH -V10 1/6] NUMA Balancing: add page promotion counter

On Mon, Nov 15, 2021 at 5:36 PM Huang Ying <ying.huang@...el.com> 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@...il.com>

>
> 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 +++++
>  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
>