From: Huang Ying <[email protected]> When swapping out THP (Transparent Huge Page), instead of swapping out the THP as a whole, sometimes we have to fallback to split the THP into normal pages before swapping, because no free swap clusters are available, or cgroup limit is exceeded, etc. To count the number of the fallback, a new VM event THP_SWPOUT_FALLBACK is added, and counted when we fallback to split the THP.
Signed-off-by: "Huang, Ying" <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Minchan Kim <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Shaohua Li <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: "Kirill A . Shutemov" <[email protected]> Cc: Michal Hocko <[email protected]> --- include/linux/vm_event_item.h | 1 + mm/vmscan.c | 3 +++ mm/vmstat.c | 1 + 3 files changed, 5 insertions(+) diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index c75024e80eed..e02820fc2861 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -86,6 +86,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, THP_ZERO_PAGE_ALLOC, THP_ZERO_PAGE_ALLOC_FAILED, THP_SWPOUT, + THP_SWPOUT_FALLBACK, #endif #ifdef CONFIG_MEMORY_BALLOON BALLOON_INFLATE, diff --git a/mm/vmscan.c b/mm/vmscan.c index 7472ddafc14a..4f7212f8ca00 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1153,6 +1153,9 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (split_huge_page_to_list(page, page_list)) goto activate_locked; +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + count_vm_event(THP_SWPOUT_FALLBACK); +#endif if (!add_to_swap(page)) goto activate_locked; } diff --git a/mm/vmstat.c b/mm/vmstat.c index bccf426453cd..e131b51654c7 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1072,6 +1072,7 @@ const char * const vmstat_text[] = { "thp_zero_page_alloc", "thp_zero_page_alloc_failed", "thp_swpout", + "thp_swpout_fallback", #endif #ifdef CONFIG_MEMORY_BALLOON "balloon_inflate", -- 2.13.2
