mm: add VM counters for transparent hugepages

I found it difficult to make sense of transparent huge pages without
having any counters for its actions.  Add some counters to vmstat for
allocation of transparent hugepages and fallback to smaller pages.

Optional patch, but useful for development and understanding the system.

Contains improvements from Andrea Arcangeli and Johannes Weiner

[akpm@linux-foundation.org: coding-style fixes]
[hannes@cmpxchg.org: fix vmstat_text[] entries]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 461c0119664ff88d2bf8797f2541ccae74ce0698..2b3831b58aa4312a754c41b2608431db85e31887 100644 (file)
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -58,6 +58,13 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
                UNEVICTABLE_PGCLEARED,  /* on COW, page truncate */
                UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
                UNEVICTABLE_MLOCKFREED,
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+               THP_FAULT_ALLOC,
+               THP_FAULT_FALLBACK,
+               THP_COLLAPSE_ALLOC,
+               THP_COLLAPSE_ALLOC_FAILED,
+               THP_SPLIT,
+#endif
                NR_VM_EVENT_ITEMS
 };
 

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0a619e0e2e0bd26da68b26948f065e1be72a8aa0..1722683bde23793f9b5287c020109a745d6830a6 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -680,8 +680,11 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                        return VM_FAULT_OOM;
                page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
                                          vma, haddr, numa_node_id(), 0);
-               if (unlikely(!page))
+               if (unlikely(!page)) {
+                       count_vm_event(THP_FAULT_FALLBACK);
                        goto out;
+               }
+               count_vm_event(THP_FAULT_ALLOC);
                if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
                        put_page(page);
                        goto out;
@@ -909,11 +912,13 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                new_page = NULL;
 
        if (unlikely(!new_page)) {
+               count_vm_event(THP_FAULT_FALLBACK);
                ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
                                                   pmd, orig_pmd, page, haddr);
                put_page(page);
                goto out;
        }
+       count_vm_event(THP_FAULT_ALLOC);
 
        if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
                put_page(new_page);
@@ -1390,6 +1395,7 @@ int split_huge_page(struct page *page)
 
        BUG_ON(!PageSwapBacked(page));
        __split_huge_page(page, anon_vma);
+       count_vm_event(THP_SPLIT);
 
        BUG_ON(PageCompound(page));
 out_unlock:
@@ -1784,9 +1790,11 @@ static void collapse_huge_page(struct mm_struct *mm,
                                      node, __GFP_OTHER_NODE);
        if (unlikely(!new_page)) {
                up_read(&mm->mmap_sem);
+               count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
                *hpage = ERR_PTR(-ENOMEM);
                return;
        }
+       count_vm_event(THP_COLLAPSE_ALLOC);
        if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
                up_read(&mm->mmap_sem);
                put_page(new_page);
@@ -2151,8 +2159,11 @@ static void khugepaged_do_scan(struct page **hpage)
 #ifndef CONFIG_NUMA
                if (!*hpage) {
                        *hpage = alloc_hugepage(khugepaged_defrag());
-                       if (unlikely(!*hpage))
+                       if (unlikely(!*hpage)) {
+                               count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
                                break;
+                       }
+                       count_vm_event(THP_COLLAPSE_ALLOC);
                }
 #else
                if (IS_ERR(*hpage))
@@ -2192,8 +2203,11 @@ static struct page *khugepaged_alloc_hugepage(void)
 
        do {
                hpage = alloc_hugepage(khugepaged_defrag());
-               if (!hpage)
+               if (!hpage) {
+                       count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
                        khugepaged_alloc_sleep();
+               } else
+                       count_vm_event(THP_COLLAPSE_ALLOC);
        } while (unlikely(!hpage) &&
                 likely(khugepaged_enabled()));
        return hpage;
@@ -2210,8 +2224,11 @@ static void khugepaged_loop(void)
        while (likely(khugepaged_enabled())) {
 #ifndef CONFIG_NUMA
                hpage = khugepaged_alloc_hugepage();
-               if (unlikely(!hpage))
+               if (unlikely(!hpage)) {
+                       count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
                        break;
+               }
+               count_vm_event(THP_COLLAPSE_ALLOC);
 #else
                if (IS_ERR(hpage)) {
                        khugepaged_alloc_sleep();

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 8cb0f0a703e59f62c8987c482fc829ab251206a5..897ea9e88238d1a9ffd99c4f35124988bbc85ef0 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -948,7 +948,16 @@ static const char * const vmstat_text[] = {
        "unevictable_pgs_cleared",
        "unevictable_pgs_stranded",
        "unevictable_pgs_mlockfreed",
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+       "thp_fault_alloc",
+       "thp_fault_fallback",
+       "thp_collapse_alloc",
+       "thp_collapse_alloc_failed",
+       "thp_split",
 #endif
+
+#endif /* CONFIG_VM_EVENTS_COUNTERS */
 };
 
 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,