Re: [PATCH v11 8/8] mm/demotion: Update node_is_toptier to work with memory tiers

Huang, Ying
2022-07-29T06:39:41Z

"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:

> With memory tiers support we can have memory only NUMA nodes
> in the top tier from which we want to avoid promotion tracking NUMA
> faults. Update node_is_toptier to work with memory tiers.
> All NUMA nodes are by default top tier nodes. With lower memory
> tiers added we consider all memory tiers above a memory tier having
> CPU NUMA nodes as a top memory tier
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
> include/linux/memory-tiers.h | 11 ++++++++++
> include/linux/node.h | 5 -----
> mm/huge_memory.c | 1 +
> mm/memory-tiers.c | 42 ++++++++++++++++++++++++++++++++++++
> mm/migrate.c | 1 +
> mm/mprotect.c | 1 +
> 6 files changed, 56 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
> index f8dbeda617a7..bc9fb9d39b2c 100644
> --- a/include/linux/memory-tiers.h
> +++ b/include/linux/memory-tiers.h
> @@ -35,6 +35,7 @@ struct memory_dev_type *init_node_memory_type(int node, struct memory_dev_type *
> #ifdef CONFIG_MIGRATION
> int next_demotion_node(int node);
> void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
> +bool node_is_toptier(int node);
> #else
> static inline int next_demotion_node(int node)
> {
> @@ -45,6 +46,11 @@ static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *target
> {
> *targets = NODE_MASK_NONE;
> }
> +
> +static inline bool node_is_toptier(int node)
> +{
> + return true;
> +}
> #endif
>
> #else
> @@ -64,5 +70,10 @@ static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *target
> {
> *targets = NODE_MASK_NONE;
> }
> +
> +static inline bool node_is_toptier(int node)
> +{
> + return true;
> +}
> #endif /* CONFIG_NUMA */
> #endif /* _LINUX_MEMORY_TIERS_H */
> diff --git a/include/linux/node.h b/include/linux/node.h
> index 40d641a8bfb0..9ec680dd607f 100644
> --- a/include/linux/node.h
> +++ b/include/linux/node.h
> @@ -185,9 +185,4 @@ 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/huge_memory.c b/mm/huge_memory.c
> index 834f288b3769..8405662646e9 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -35,6 +35,7 @@
> #include <linux/numa.h>
> #include <linux/page_owner.h>
> #include <linux/sched/sysctl.h>
> +#include <linux/memory-tiers.h>
>
> #include <asm/tlb.h>
> #include <asm/pgalloc.h>
> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> index 84e2be31a853..36d87dc422ab 100644
> --- a/mm/memory-tiers.c
> +++ b/mm/memory-tiers.c
> @@ -30,6 +30,7 @@ static DEFINE_MUTEX(memory_tier_lock);
> static LIST_HEAD(memory_tiers);
> struct memory_dev_type *node_memory_types[MAX_NUMNODES];
> #ifdef CONFIG_MIGRATION
> +static int top_tier_adistance;
> /*
> * node_demotion[] examples:
> *
> @@ -159,6 +160,31 @@ static struct memory_tier *__node_get_memory_tier(int node)
> }
>
> #ifdef CONFIG_MIGRATION
> +bool node_is_toptier(int node)
> +{
> + bool toptier;
> + pg_data_t *pgdat;
> + struct memory_tier *memtier;
> +
> + pgdat = NODE_DATA(node);
> + if (!pgdat)
> + return false;
> +
> + rcu_read_lock();
> + memtier = rcu_dereference(pgdat->memtier);
> + if (!memtier) {
> + toptier = true;
> + goto out;
> + }
> + if (memtier->adistance_start >= top_tier_adistance)
> + toptier = true;
> + else
> + toptier = false;
> +out:
> + rcu_read_unlock();
> + return toptier;
> +}
> +
> void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
> {
> struct memory_tier *memtier;
> @@ -315,6 +341,22 @@ static void establish_demotion_targets(void)
> }
> } while (1);
> }
> + /*
> + * Promotion is allowed from a memory tier to higher
> + * memory tier only if the memory tier doesn't include
> + * compute. We want to skip promotion from a memory tier,
> + * if any node that is part of the memory tier have CPUs.
> + * Once we detect such a memory tier, we consider that tier
> + * as top tiper from which promotion on is not allowed.
> + */
> + list_for_each_entry(memtier, &memory_tiers, list) {
> + tier_nodes = get_memtier_nodemask(memtier);
> + nodes_and(tier_nodes, node_states[N_CPU], tier_nodes);
> + if (!nodes_empty(tier_nodes)) {
> + top_tier_adistance = memtier->adistance_start;

IMHO, this should be,

top_tier_adistance = memtier->adistance_start + MEMTIER_CHUNK_SIZE;

Best Regards,
Huang, Ying

> + break;
> + }
> + }
> /*
> * Now build the lower_tier mask for each node collecting node mask from
> * all memory tier below it. This allows us to fallback demotion page
> diff --git a/mm/migrate.c b/mm/migrate.c
> index c758c9c21d7d..1da81136eaaa 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -50,6 +50,7 @@
> #include <linux/memory.h>
> #include <linux/random.h>
> #include <linux/sched/sysctl.h>
> +#include <linux/memory-tiers.h>
>
> #include <asm/tlbflush.h>
>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index ba5592655ee3..92a2fc0fa88b 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -31,6 +31,7 @@
> #include <linux/pgtable.h>
> #include <linux/sched/sysctl.h>
> #include <linux/userfaultfd_k.h>
> +#include <linux/memory-tiers.h>
> #include <asm/cacheflush.h>
> #include <asm/mmu_context.h>
> #include <asm/tlbflush.h>