mm: memcg: add THP swap out info for anonymous reclaim

At present, we support per-memcg reclaim strategy, however we do not know the number of transparent huge pages being reclaimed, as we know the transparent huge pages need to be splited before reclaim them, and they will bring some performance bottleneck effect. for example, when two memcg (A & B) are doing reclaim for anonymous pages at same time, and 'A' memcg is reclaiming a large number of transparent huge pages, we can better analyze that the performance bottleneck will be caused by 'A' memcg. therefore, in order to better analyze such problems, there add THP swap out info for per-memcg. [[email protected] fix swap_writepage_fs(), per Johannes] Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Xin Hao <[email protected]> Suggested-by: Johannes Weiner <[email protected]> Acked-by: Johannes Weiner <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Shakeel Butt <[email protected]> Cc: Muchun Song <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
niw · Oct 4, 2023 · 811244a · 811244a
1 parent ed547ab
commit 811244a
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diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
@@ -1532,6 +1532,15 @@ PAGE_SIZE multiple when read back.
 		collapsing an existing range of pages. This counter is not
 		present when CONFIG_TRANSPARENT_HUGEPAGE is not set.
 
+	  thp_swpout (npn)
+		Number of transparent hugepages which are swapout in one piece
+		without splitting.
+
+	  thp_swpout_fallback (npn)
+		Number of transparent hugepages which were split before swapout.
+		Usually because failed to allocate some continuous swap space
+		for the huge page.
+
   memory.numa_stat
 	A read-only nested-keyed file which exists on non-root cgroups.
 

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
@@ -704,6 +704,8 @@ static const unsigned int memcg_vm_event_stat[] = {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	THP_FAULT_ALLOC,
 	THP_COLLAPSE_ALLOC,
+	THP_SWPOUT,
+	THP_SWPOUT_FALLBACK,
 #endif
 };
 

diff --git a/mm/page_io.c b/mm/page_io.c
@@ -208,8 +208,10 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
 static inline void count_swpout_vm_event(struct folio *folio)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	if (unlikely(folio_test_pmd_mappable(folio)))
+	if (unlikely(folio_test_pmd_mappable(folio))) {
+		count_memcg_folio_events(folio, THP_SWPOUT, 1);
 		count_vm_event(THP_SWPOUT);
+	}
 #endif
 	count_vm_events(PSWPOUT, folio_nr_pages(folio));
 }
@@ -278,9 +280,6 @@ static void sio_write_complete(struct kiocb *iocb, long ret)
 			set_page_dirty(page);
 			ClearPageReclaim(page);
 		}
-	} else {
-		for (p = 0; p < sio->pages; p++)
-			count_swpout_vm_event(page_folio(sio->bvec[p].bv_page));
 	}
 
 	for (p = 0; p < sio->pages; p++)
@@ -296,6 +295,7 @@ static void swap_writepage_fs(struct page *page, struct writeback_control *wbc)
 	struct file *swap_file = sis->swap_file;
 	loff_t pos = page_file_offset(page);
 
+	count_swpout_vm_event(page_folio(page));
 	set_page_writeback(page);
 	unlock_page(page);
 	if (wbc->swap_plug)

diff --git a/mm/vmscan.c b/mm/vmscan.c
@@ -1214,6 +1214,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
 								folio_list))
 						goto activate_locked;
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
+					count_memcg_folio_events(folio, THP_SWPOUT_FALLBACK, 1);
 					count_vm_event(THP_SWPOUT_FALLBACK);
 #endif
 					if (!add_to_swap(folio))