Re: [RFC PATCH v3 5/7] mm/damon/paddr: introduce DAMOS_MIGRATE_COLD action for demotion

Hyeongtak Ji
2024-04-05T07:56:12Z

On Fri, 5 Apr 2024 15:08:54 +0900 Honggyu Kim <honggyu.kim@sk.com> wrote:

...snip...

> +static unsigned long damon_pa_migrate_pages(struct list_head *folio_list,
> + enum migration_mode mm,
> + int target_nid)
> +{
> + int nid;
> + unsigned int nr_migrated = 0;
> + LIST_HEAD(node_folio_list);
> + unsigned int noreclaim_flag;
> +
> + if (list_empty(folio_list))
> + return nr_migrated;

How about checking if `target_nid` is `NUMA_NO_NODE` or not earlier,

> +
> + noreclaim_flag = memalloc_noreclaim_save();
> +
> + nid = folio_nid(lru_to_folio(folio_list));
> + do {
> + struct folio *folio = lru_to_folio(folio_list);
> +
> + if (nid == folio_nid(folio)) {
> + folio_clear_active(folio);
> + list_move(&folio->lru, &node_folio_list);
> + continue;
> + }
> +
> + nr_migrated += damon_pa_migrate_folio_list(&node_folio_list,
> + NODE_DATA(nid), mm,
> + target_nid);
> + nid = folio_nid(lru_to_folio(folio_list));
> + } while (!list_empty(folio_list));
> +
> + nr_migrated += damon_pa_migrate_folio_list(&node_folio_list,
> + NODE_DATA(nid), mm,
> + target_nid);
> +
> + memalloc_noreclaim_restore(noreclaim_flag);
> +
> + return nr_migrated;
> +}
> +

...snip...

> +static unsigned int migrate_folio_list(struct list_head *migrate_folios,
> + struct pglist_data *pgdat,
> + int target_nid)
> +{
> + unsigned int nr_succeeded;
> + nodemask_t allowed_mask = NODE_MASK_NONE;
> +
> + struct migration_target_control mtc = {
> + /*
> + * Allocate from 'node', or fail quickly and quietly.
> + * When this happens, 'page' will likely just be discarded
> + * instead of migrated.
> + */
> + .gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | __GFP_NOWARN |
> + __GFP_NOMEMALLOC | GFP_NOWAIT,
> + .nid = target_nid,
> + .nmask = &allowed_mask
> + };
> +
> + if (pgdat->node_id == target_nid || target_nid == NUMA_NO_NODE)
> + return 0;

instead of here.

> +
> + if (list_empty(migrate_folios))
> + return 0;
> +
> + /* Migration ignores all cpuset and mempolicy settings */
> + migrate_pages(migrate_folios, alloc_migrate_folio, NULL,
> + (unsigned long)&mtc, MIGRATE_ASYNC, MR_DAMON,
> + &nr_succeeded);
> +
> + return nr_succeeded;
> +}
> +

...snip...

Kind regards,
Hyeongtak