[PATCHv3 13/24] mm, vmstats: new THP splitting event

Kirill A. Shutemov
2015-02-12T16:24:26Z

The patch replaces THP_SPLIT with tree events: THP_SPLIT_PAGE,
THP_SPLIT_PAGE_FAILT and THP_SPLIT_PMD. It reflects the fact that we
now can split PMD without the compound page and that split_huge_page()
can fail.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/vm_event_item.h | 4 +++-
mm/huge_memory.c | 3 +++
mm/vmstat.c | 4 +++-
3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 2b1cef88b827..3261bfe2156a 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -69,7 +69,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
THP_FAULT_FALLBACK,
THP_COLLAPSE_ALLOC,
THP_COLLAPSE_ALLOC_FAILED,
- THP_SPLIT,
+ THP_SPLIT_PAGE,
+ THP_SPLIT_PAGE_FAILED,
+ THP_SPLIT_PMD,
THP_ZERO_PAGE_ALLOC,
THP_ZERO_PAGE_ALLOC_FAILED,
#endif
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 46c3cd26f837..b5c1976e2a65 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1644,6 +1644,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma,

BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);

+ count_vm_event(THP_SPLIT_PMD);
+
if (is_huge_zero_pmd(*pmd))
return __split_huge_zero_page_pmd(vma, haddr, pmd);

@@ -1917,6 +1919,7 @@ static void __split_huge_page(struct page *page,
*/
int split_huge_page_to_list(struct page *page, struct list_head *list)
{
+ count_vm_event(THP_SPLIT_PAGE_FAILED);
return -EBUSY;
}

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 1fd0886a389f..e1c87425fe11 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -821,7 +821,9 @@ const char * const vmstat_text[] = {
"thp_fault_fallback",
"thp_collapse_alloc",
"thp_collapse_alloc_failed",
- "thp_split",
+ "thp_split_page",
+ "thp_split_page_failed",
+ "thp_split_pmd",
"thp_zero_page_alloc",
"thp_zero_page_alloc_failed",
#endif
--
2.1.4