From: Yang Yang <yang.yang29@xxxxxxxxxx> Subject: mm/vmstat: add events for THP max_ptes_* exceeds There are interfaces to adjust max_ptes_none, max_ptes_swap, max_ptes_shared values, see /sys/kernel/mm/transparent_hugepage/khugepaged/. But system administrator maynot know which value is the best. So Add those events to support adjusting max_ptes_* to suitable values. For example, if default max_ptes_swap value causes too much failures, and system uses zram whose IO is fast, administrator could increase max_ptes_swap until THP_SCAN_EXCEED_SWAP_PTE not increase anymore. Link: https://lkml.kernel.org/r/20211225094036.574157-1-yang.yang29@xxxxxxxxxx Signed-off-by: Yang Yang <yang.yang29@xxxxxxxxxx> Cc: "Huang, Ying" <ying.huang@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Saravanan D <saravanand@xxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/vm_event_item.h | 3 +++ mm/khugepaged.c | 7 +++++++ mm/vmstat.c | 3 +++ 3 files changed, 13 insertions(+) --- a/include/linux/vm_event_item.h~mm-vmstat-add-events-for-thp-max_ptes_-exceeds +++ a/include/linux/vm_event_item.h @@ -98,6 +98,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS THP_SPLIT_PAGE_FAILED, THP_DEFERRED_SPLIT_PAGE, THP_SPLIT_PMD, + THP_SCAN_EXCEED_NONE_PTE, + THP_SCAN_EXCEED_SWAP_PTE, + THP_SCAN_EXCEED_SHARED_PTE, #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD THP_SPLIT_PUD, #endif --- a/mm/khugepaged.c~mm-vmstat-add-events-for-thp-max_ptes_-exceeds +++ a/mm/khugepaged.c @@ -618,6 +618,7 @@ static int __collapse_huge_page_isolate( continue; } else { result = SCAN_EXCEED_NONE_PTE; + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); goto out; } } @@ -636,6 +637,7 @@ static int __collapse_huge_page_isolate( if (page_mapcount(page) > 1 && ++shared > khugepaged_max_ptes_shared) { result = SCAN_EXCEED_SHARED_PTE; + count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); goto out; } @@ -1253,6 +1255,7 @@ static int khugepaged_scan_pmd(struct mm continue; } else { result = SCAN_EXCEED_SWAP_PTE; + count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); goto out_unmap; } } @@ -1262,6 +1265,7 @@ static int khugepaged_scan_pmd(struct mm continue; } else { result = SCAN_EXCEED_NONE_PTE; + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); goto out_unmap; } } @@ -1290,6 +1294,7 @@ static int khugepaged_scan_pmd(struct mm if (page_mapcount(page) > 1 && ++shared > khugepaged_max_ptes_shared) { result = SCAN_EXCEED_SHARED_PTE; + count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); goto out_unmap; } @@ -2000,6 +2005,7 @@ static void khugepaged_scan_file(struct if (xa_is_value(page)) { if (++swap > khugepaged_max_ptes_swap) { result = SCAN_EXCEED_SWAP_PTE; + count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); break; } continue; @@ -2046,6 +2052,7 @@ static void khugepaged_scan_file(struct if (result == SCAN_SUCCEED) { if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { result = SCAN_EXCEED_NONE_PTE; + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); } else { node = khugepaged_find_target_node(); collapse_file(mm, file, start, hpage, node); --- a/mm/vmstat.c~mm-vmstat-add-events-for-thp-max_ptes_-exceeds +++ a/mm/vmstat.c @@ -1353,6 +1353,9 @@ const char * const vmstat_text[] = { "thp_split_page_failed", "thp_deferred_split_page", "thp_split_pmd", + "thp_scan_exceed_none_pte", + "thp_scan_exceed_swap_pte", + "thp_scan_exceed_share_pte", #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD "thp_split_pud", #endif _
