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

Aneesh Kumar K V
2022-07-29T06:42:47Z

On 7/29/22 12:09 PM, Huang, Ying wrote:
> "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;
>

Good catch. Will update. BTW i did send v12 version of the patchset already to the list.

-aneesh