Re: [PATCH v6 04/13] mm/demotion/dax/kmem: Set node's memory tier to MEMORY_TIER_PMEM

Ying Huang
2022-06-13T06:59:25Z

On Fri, 2022-06-10 at 19:22 +0530, Aneesh Kumar K.V wrote:
> By default, all nodes are assigned to DEFAULT_MEMORY_TIER which
> is the memory tier designated for nodes with DRAM
>
> Set dax kmem device node's tier to MEMORY_TIER_PMEM. MEMORY_TIER_PMEM
> is assigned a default rank value of 100 and appears below DEFAULT_MEMORY_TIER
> in demotion order.
>
> Signed-off-by: Jagdish Gediya <jvgediya@linux.ibm.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
>  drivers/dax/kmem.c | 4 ++
>  include/linux/memory-tiers.h | 1 +
>  mm/memory-tiers.c | 78 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 83 insertions(+)
>
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index a37622060fff..0cb3de3d138f 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -11,6 +11,7 @@
>  #include <linux/fs.h>
>  #include <linux/mm.h>
>  #include <linux/mman.h>
> +#include <linux/memory-tiers.h>
>  #include "dax-private.h"
>  #include "bus.h"
>
>
> @@ -147,6 +148,9 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
>
>
>   dev_set_drvdata(dev, data);
>
>
> +#ifdef CONFIG_TIERED_MEMORY
> + node_create_and_set_memory_tier(numa_node, MEMORY_TIER_PMEM);
> +#endif
>   return 0;
>
>
>  err_request_mem:
> diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
> index 44c3c3b16a36..e102ec73ab80 100644
> --- a/include/linux/memory-tiers.h
> +++ b/include/linux/memory-tiers.h
> @@ -18,6 +18,7 @@
>  #define MAX_MEMORY_TIERS 3
>
>
>  extern bool numa_demotion_enabled;
> +int node_create_and_set_memory_tier(int node, int tier);
>  #else
>  #define numa_demotion_enabled false
>
>
> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> index c3123a457d90..00d393a5a628 100644
> --- a/mm/memory-tiers.c
> +++ b/mm/memory-tiers.c
> @@ -67,6 +67,84 @@ static struct memory_tier *register_memory_tier(unsigned int tier,
>   return memtier;
>  }
>
>
> +static struct memory_tier *__node_get_memory_tier(int node)
> +{
> + struct memory_tier *memtier;
> +
> + list_for_each_entry(memtier, &memory_tiers, list) {
> + if (node_isset(node, memtier->nodelist))
> + return memtier;
> + }
> + return NULL;
> +}
> +

I suggest to add NODE_DATA(nid)->mem_tier before this patch. That is,
part of [9/13]. That will make code much simpler and easier to
review.

And, in addition to dax_kmem, whenever a normal node is onlined, we
need to add it to the default memory tier. I found this is done in
[5/13]. IMHO, we should move that part before this patch.

Best Regards,
Huang, Ying

> +static struct memory_tier *__get_memory_tier_from_id(int id)
> +{
> + struct memory_tier *memtier;
> +
> + list_for_each_entry(memtier, &memory_tiers, list) {
> + if (memtier->id == id)
> + return memtier;
> + }
> + return NULL;
> +}
> +
> +static int __node_create_and_set_memory_tier(int node, int tier)
> +{
> + int ret = 0;
> + struct memory_tier *memtier;
> +
> + memtier = __get_memory_tier_from_id(tier);
> + if (!memtier) {
> + int rank;
> +
> + rank = get_rank_from_tier(tier);
> + if (rank == -1) {
> + ret = -EINVAL;
> + goto out;
> + }
> + memtier = register_memory_tier(tier, rank);
> + if (!memtier) {
> + ret = -EINVAL;
> + goto out;
> + }
> + }
> + node_set(node, memtier->nodelist);
> +out:
> + return ret;
> +}
> +
> +int node_create_and_set_memory_tier(int node, int tier)
> +{
> + struct memory_tier *current_tier;
> + int ret = 0;
> +
> + mutex_lock(&memory_tier_lock);
> +
> + current_tier = __node_get_memory_tier(node);
> + if (!current_tier) {
> + ret = __node_create_and_set_memory_tier(node, tier);
> + goto out;
> + }
> +
> + if (current_tier->id == tier)
> + goto out;
> +
> + node_clear(node, current_tier->nodelist);
> +
> + ret = __node_create_and_set_memory_tier(node, tier);
> + if (ret) {
> + /* reset it back to older tier */
> + node_set(node, current_tier->nodelist);
> + goto out;
> + }
> +out:
> + mutex_unlock(&memory_tier_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(node_create_and_set_memory_tier);
> +
>  static int __init memory_tier_init(void)
>  {
>   struct memory_tier *memtier;