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 5b5b0f094060..66effbadc9b8 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -85,6 +85,7 @@ 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 510e709aecd4..0f5a6bfc5e65 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 ebfd79df1008..9400c915e9a2 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1071,6 +1071,7 @@ 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", -- 2.11.0
