Hi, Alistair,
Alistair Popple <apopple@xxxxxxxxxx> writes:
> Looks good. Please add my reviewed by from v1 as well:
>
> Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx>
Sorry, I just found your email in my junk email folder. It appears that
there are some bugs in my email system. I will be more careful in the
future and try to find a way to fix my email system.
Thanks Andrew to help add your reviewed-by in his merged version.
Best Regards,
Huang, Ying
> Huang Ying <ying.huang@xxxxxxxxx> writes:
>
>> After recent changes to the retrying and failure counting in
>> migrate_pages_batch(), it was found that it's unnecessary to count
>> retrying and failure for normal, large, and THP folios separately.
>> Because we don't use retrying and failure number of large folios
>> directly. So, in this patch, we simplified retrying and failure
>> counting of large folios via counting retrying and failure of normal
>> and large folios together. This results in the reduced line number.
>>
>> Previously, in migrate_pages_batch we need to track whether the source
>> folio is large/THP before splitting. So is_large is used to cache
>> folio_test_large() result. Now, we don't need that variable any more
>> because we don't count retrying and failure of large folios (only
>> counting that of THP folios). So, in this patch, is_large is removed
>> to simplify the code.
>>
>> This is just code cleanup, no functionality changes are expected.
>>
>> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
>> Reviewed-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
>> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
>> Cc: Yang Shi <shy828301@xxxxxxxxx>
>> Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
>> Cc: Oscar Salvador <osalvador@xxxxxxx>
>> Cc: Alistair Popple <apopple@xxxxxxxxxx>
>> ---
>> mm/migrate.c | 110 ++++++++++++++++-----------------------------------
>> 1 file changed, 35 insertions(+), 75 deletions(-)
>>
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 01cac26a3127..2ac927a82bbc 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1614,13 +1614,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> int nr_pass)
>> {
>> int retry = 1;
>> - int large_retry = 1;
>> int thp_retry = 1;
>> int nr_failed = 0;
>> int nr_retry_pages = 0;
>> - int nr_large_failed = 0;
>> int pass = 0;
>> - bool is_large = false;
>> bool is_thp = false;
>> struct folio *folio, *folio2, *dst = NULL, *dst2;
>> int rc, rc_saved = 0, nr_pages;
>> @@ -1631,20 +1628,13 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
>> !list_empty(from) && !list_is_singular(from));
>>
>> - for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
>> + for (pass = 0; pass < nr_pass && retry; pass++) {
>> retry = 0;
>> - large_retry = 0;
>> thp_retry = 0;
>> nr_retry_pages = 0;
>>
>> list_for_each_entry_safe(folio, folio2, from, lru) {
>> - /*
>> - * Large folio statistics is based on the source large
>> - * folio. Capture required information that might get
>> - * lost during migration.
>> - */
>> - is_large = folio_test_large(folio);
>> - is_thp = is_large && folio_test_pmd_mappable(folio);
>> + is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>> nr_pages = folio_nr_pages(folio);
>>
>> cond_resched();
>> @@ -1660,7 +1650,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> * list is processed.
>> */
>> if (!thp_migration_supported() && is_thp) {
>> - nr_large_failed++;
>> + nr_failed++;
>> stats->nr_thp_failed++;
>> if (!try_split_folio(folio, split_folios)) {
>> stats->nr_thp_split++;
>> @@ -1688,38 +1678,33 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> * When memory is low, don't bother to try to migrate
>> * other folios, move unmapped folios, then exit.
>> */
>> - if (is_large) {
>> - nr_large_failed++;
>> - 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);
>> + nr_failed++;
>> + stats->nr_thp_failed += is_thp;
>> + /* Large folio NUMA faulting doesn't split to retry. */
>> + if (folio_test_large(folio) && !nosplit) {
>> + int ret = try_split_folio(folio, split_folios);
>>
>> - if (!ret) {
>> - stats->nr_thp_split += is_thp;
>> - break;
>> - } else if (reason == MR_LONGTERM_PIN &&
>> - ret == -EAGAIN) {
>> - /*
>> - * Try again to split large folio to
>> - * mitigate the failure of longterm pinning.
>> - */
>> - large_retry++;
>> - thp_retry += is_thp;
>> - nr_retry_pages += nr_pages;
>> - /* Undo duplicated failure counting. */
>> - nr_large_failed--;
>> - stats->nr_thp_failed -= is_thp;
>> - break;
>> - }
>> + if (!ret) {
>> + stats->nr_thp_split += is_thp;
>> + break;
>> + } else if (reason == MR_LONGTERM_PIN &&
>> + ret == -EAGAIN) {
>> + /*
>> + * Try again to split large folio to
>> + * mitigate the failure of longterm pinning.
>> + */
>> + retry++;
>> + thp_retry += is_thp;
>> + nr_retry_pages += nr_pages;
>> + /* Undo duplicated failure counting. */
>> + nr_failed--;
>> + stats->nr_thp_failed -= is_thp;
>> + break;
>> }
>> - } else {
>> - nr_failed++;
>> }
>>
>> stats->nr_failed_pages += nr_pages + nr_retry_pages;
>> /* nr_failed isn't updated for not used */
>> - nr_large_failed += large_retry;
>> stats->nr_thp_failed += thp_retry;
>> rc_saved = rc;
>> if (list_empty(&unmap_folios))
>> @@ -1727,12 +1712,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> else
>> goto move;
>> case -EAGAIN:
>> - if (is_large) {
>> - large_retry++;
>> - thp_retry += is_thp;
>> - } else {
>> - retry++;
>> - }
>> + retry++;
>> + thp_retry += is_thp;
>> nr_retry_pages += nr_pages;
>> break;
>> case MIGRATEPAGE_SUCCESS:
>> @@ -1750,20 +1731,14 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> * removed from migration folio list and not
>> * retried in the next outer loop.
>> */
>> - if (is_large) {
>> - nr_large_failed++;
>> - stats->nr_thp_failed += is_thp;
>> - } else {
>> - nr_failed++;
>> - }
>> -
>> + nr_failed++;
>> + stats->nr_thp_failed += is_thp;
>> stats->nr_failed_pages += nr_pages;
>> break;
>> }
>> }
>> }
>> nr_failed += retry;
>> - nr_large_failed += large_retry;
>> stats->nr_thp_failed += thp_retry;
>> stats->nr_failed_pages += nr_retry_pages;
>> move:
>> @@ -1771,17 +1746,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> try_to_unmap_flush();
>>
>> retry = 1;
>> - for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
>> + for (pass = 0; pass < nr_pass && retry; pass++) {
>> retry = 0;
>> - large_retry = 0;
>> thp_retry = 0;
>> nr_retry_pages = 0;
>>
>> dst = list_first_entry(&dst_folios, struct folio, lru);
>> dst2 = list_next_entry(dst, lru);
>> list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
>> - is_large = folio_test_large(folio);
>> - is_thp = is_large && folio_test_pmd_mappable(folio);
>> + is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>> nr_pages = folio_nr_pages(folio);
>>
>> cond_resched();
>> @@ -1797,12 +1770,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> */
>> switch(rc) {
>> case -EAGAIN:
>> - if (is_large) {
>> - large_retry++;
>> - thp_retry += is_thp;
>> - } else {
>> - retry++;
>> - }
>> + retry++;
>> + thp_retry += is_thp;
>> nr_retry_pages += nr_pages;
>> break;
>> case MIGRATEPAGE_SUCCESS:
>> @@ -1810,13 +1779,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> stats->nr_thp_succeeded += is_thp;
>> break;
>> default:
>> - if (is_large) {
>> - nr_large_failed++;
>> - stats->nr_thp_failed += is_thp;
>> - } else {
>> - nr_failed++;
>> - }
>> -
>> + nr_failed++;
>> + stats->nr_thp_failed += is_thp;
>> stats->nr_failed_pages += nr_pages;
>> break;
>> }
>> @@ -1825,14 +1789,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>> }
>> }
>> nr_failed += retry;
>> - nr_large_failed += large_retry;
>> stats->nr_thp_failed += thp_retry;
>> stats->nr_failed_pages += nr_retry_pages;
>>
>> - if (rc_saved)
>> - rc = rc_saved;
>> - else
>> - rc = nr_failed + nr_large_failed;
>> + rc = rc_saved ? : nr_failed;
>> out:
>> /* Cleanup remaining folios */
>> dst = list_first_entry(&dst_folios, struct folio, lru);
