Re: [PATCH -v2 1/9] migrate_pages: organize stats with struct migrate_pages_stats

[Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>]

On 1/10/2023 3:53 PM, Huang Ying wrote:
> Define struct migrate_pages_stats to organize the various statistics
> in migrate_pages().  This makes it easier to collect and consume the
> statistics in multiple functions.  This will be needed in the
> following patches in the series.
>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx>
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> Cc: Yang Shi <shy828301@xxxxxxxxx>
> Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Cc: Bharata B Rao <bharata@xxxxxxx>
> Cc: haoxin <xhao@xxxxxxxxxxxxxxxxx>
> ---
>   mm/migrate.c | 60 +++++++++++++++++++++++++++++-----------------------
>   1 file changed, 34 insertions(+), 26 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index a4d3fc65085f..d21de40861a0 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1396,6 +1396,16 @@ static inline int try_split_folio(struct folio *folio, struct list_head *split_f
>   	return rc;
>   }
>   
> +struct migrate_pages_stats {
> +	int nr_succeeded;	/* Normal pages and THP migrated successfully, in units
> +				   of base pages */
> +	int nr_failed_pages;	/* Normal pages and THP failed to be migrated, in units
> +				   of base pages.  Untried pages aren't counted */

I think above 2 fields also contain the number of hugetlb pages. 
Otherwise looks good to me.

Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>


> +	int nr_thp_succeeded;	/* THP migrated successfully */
> +	int nr_thp_failed;	/* THP failed to be migrated */
> +	int nr_thp_split;	/* THP split before migrating */
> +};
> +
>   /*
>    * migrate_pages - migrate the folios specified in a list, to the free folios
>    *		   supplied as the target for the page migration
> @@ -1430,13 +1440,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   	int large_retry = 1;
>   	int thp_retry = 1;
>   	int nr_failed = 0;
> -	int nr_failed_pages = 0;
>   	int nr_retry_pages = 0;
> -	int nr_succeeded = 0;
> -	int nr_thp_succeeded = 0;
>   	int nr_large_failed = 0;
> -	int nr_thp_failed = 0;
> -	int nr_thp_split = 0;
>   	int pass = 0;
>   	bool is_large = false;
>   	bool is_thp = false;
> @@ -1446,9 +1451,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   	LIST_HEAD(split_folios);
>   	bool nosplit = (reason == MR_NUMA_MISPLACED);
>   	bool no_split_folio_counting = false;
> +	struct migrate_pages_stats stats;
>   
>   	trace_mm_migrate_pages_start(mode, reason);
>   
> +	memset(&stats, 0, sizeof(stats));
>   split_folio_migration:
>   	for (pass = 0; pass < 10 && (retry || large_retry); pass++) {
>   		retry = 0;
> @@ -1502,9 +1509,9 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   				/* Large folio migration is unsupported */
>   				if (is_large) {
>   					nr_large_failed++;
> -					nr_thp_failed += is_thp;
> +					stats.nr_thp_failed += is_thp;
>   					if (!try_split_folio(folio, &split_folios)) {
> -						nr_thp_split += is_thp;
> +						stats.nr_thp_split += is_thp;
>   						break;
>   					}
>   				/* Hugetlb migration is unsupported */
> @@ -1512,7 +1519,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   					nr_failed++;
>   				}
>   
> -				nr_failed_pages += nr_pages;
> +				stats.nr_failed_pages += nr_pages;
>   				list_move_tail(&folio->lru, &ret_folios);
>   				break;
>   			case -ENOMEM:
> @@ -1522,13 +1529,13 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   				 */
>   				if (is_large) {
>   					nr_large_failed++;
> -					nr_thp_failed += is_thp;
> +					stats.nr_thp_failed += is_thp;
>   					/* Large folio NUMA faulting doesn't split to retry. */
>   					if (!nosplit) {
>   						int ret = try_split_folio(folio, &split_folios);
>   
>   						if (!ret) {
> -							nr_thp_split += is_thp;
> +							stats.nr_thp_split += is_thp;
>   							break;
>   						} else if (reason == MR_LONGTERM_PIN &&
>   							   ret == -EAGAIN) {
> @@ -1546,7 +1553,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   					nr_failed++;
>   				}
>   
> -				nr_failed_pages += nr_pages + nr_retry_pages;
> +				stats.nr_failed_pages += nr_pages + nr_retry_pages;
>   				/*
>   				 * There might be some split folios of fail-to-migrate large
>   				 * folios left in split_folios list. Move them back to migration
> @@ -1556,7 +1563,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   				list_splice_init(&split_folios, from);
>   				/* nr_failed isn't updated for not used */
>   				nr_large_failed += large_retry;
> -				nr_thp_failed += thp_retry;
> +				stats.nr_thp_failed += thp_retry;
>   				goto out;
>   			case -EAGAIN:
>   				if (is_large) {
> @@ -1568,8 +1575,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   				nr_retry_pages += nr_pages;
>   				break;
>   			case MIGRATEPAGE_SUCCESS:
> -				nr_succeeded += nr_pages;
> -				nr_thp_succeeded += is_thp;
> +				stats.nr_succeeded += nr_pages;
> +				stats.nr_thp_succeeded += is_thp;
>   				break;
>   			default:
>   				/*
> @@ -1580,20 +1587,20 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   				 */
>   				if (is_large) {
>   					nr_large_failed++;
> -					nr_thp_failed += is_thp;
> +					stats.nr_thp_failed += is_thp;
>   				} else if (!no_split_folio_counting) {
>   					nr_failed++;
>   				}
>   
> -				nr_failed_pages += nr_pages;
> +				stats.nr_failed_pages += nr_pages;
>   				break;
>   			}
>   		}
>   	}
>   	nr_failed += retry;
>   	nr_large_failed += large_retry;
> -	nr_thp_failed += thp_retry;
> -	nr_failed_pages += nr_retry_pages;
> +	stats.nr_thp_failed += thp_retry;
> +	stats.nr_failed_pages += nr_retry_pages;
>   	/*
>   	 * Try to migrate split folios of fail-to-migrate large folios, no
>   	 * nr_failed counting in this round, since all split folios of a
> @@ -1626,16 +1633,17 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   	if (list_empty(from))
>   		rc = 0;
>   
> -	count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
> -	count_vm_events(PGMIGRATE_FAIL, nr_failed_pages);
> -	count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded);
> -	count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed);
> -	count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split);
> -	trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded,
> -			       nr_thp_failed, nr_thp_split, mode, reason);
> +	count_vm_events(PGMIGRATE_SUCCESS, stats.nr_succeeded);
> +	count_vm_events(PGMIGRATE_FAIL, stats.nr_failed_pages);
> +	count_vm_events(THP_MIGRATION_SUCCESS, stats.nr_thp_succeeded);
> +	count_vm_events(THP_MIGRATION_FAIL, stats.nr_thp_failed);
> +	count_vm_events(THP_MIGRATION_SPLIT, stats.nr_thp_split);
> +	trace_mm_migrate_pages(stats.nr_succeeded, stats.nr_failed_pages,
> +			       stats.nr_thp_succeeded, stats.nr_thp_failed,
> +			       stats.nr_thp_split, mode, reason);
>   
>   	if (ret_succeeded)
> -		*ret_succeeded = nr_succeeded;
> +		*ret_succeeded = stats.nr_succeeded;
>   
>   	return rc;
>   }