From 85b9f46e8ea451633ccd60a7d8cacbfff9f34047 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 6 Apr 2020 20:04:28 -0700 Subject: [PATCH 1/1] mm, thp: track fallbacks due to failed memcg charges separately The thp_fault_fallback and thp_file_fallback vmstats are incremented if either the hugepage allocation fails through the page allocator or the hugepage charge fails through mem cgroup. This patch leaves this field untouched but adds two new fields, thp_{fault,file}_fallback_charge, which is incremented only when the mem cgroup charge fails. This distinguishes between attempted hugepage allocations that fail due to fragmentation (or low memory conditions) and those that fail due to mem cgroup limits. That can be used to determine the impact of fragmentation on the system by excluding faults that failed due to memcg usage. Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Reviewed-by: Yang Shi Acked-by: Kirill A. Shutemov Cc: Mike Rapoport Cc: Jeremy Cline Cc: Andrea Arcangeli Cc: Mike Kravetz Cc: Michal Hocko Cc: Vlastimil Babka Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2003061422070.7412@chino.kir.corp.google.com Signed-off-by: Linus Torvalds --- Documentation/admin-guide/mm/transhuge.rst | 10 ++++++++++ include/linux/vm_event_item.h | 3 +++ mm/huge_memory.c | 2 ++ mm/shmem.c | 4 +++- mm/vmstat.c | 2 ++ 5 files changed, 20 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index f79ebbcd6725..2f31de8f7c74 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -310,6 +310,11 @@ thp_fault_fallback is incremented if a page fault fails to allocate a huge page and instead falls back to using small pages. +thp_fault_fallback_charge + is incremented if a page fault fails to charge a huge page and + instead falls back to using small pages even though the + allocation was successful. + thp_collapse_alloc_failed is incremented if khugepaged found a range of pages that should be collapsed into one huge page but failed @@ -323,6 +328,11 @@ thp_file_fallback is incremented if a file huge page is attempted to be allocated but fails and instead falls back to using small pages. +thp_file_fallback_charge + is incremented if a file huge page cannot be charged and instead + falls back to using small pages even though the allocation was + successful. + thp_file_mapped is incremented every time a file huge page is mapped into user address space. diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index 41a4c7568748..ffef0f279747 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -73,10 +73,12 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, #ifdef CONFIG_TRANSPARENT_HUGEPAGE THP_FAULT_ALLOC, THP_FAULT_FALLBACK, + THP_FAULT_FALLBACK_CHARGE, THP_COLLAPSE_ALLOC, THP_COLLAPSE_ALLOC_FAILED, THP_FILE_ALLOC, THP_FILE_FALLBACK, + THP_FILE_FALLBACK_CHARGE, THP_FILE_MAPPED, THP_SPLIT_PAGE, THP_SPLIT_PAGE_FAILED, @@ -117,6 +119,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, #ifndef CONFIG_TRANSPARENT_HUGEPAGE #define THP_FILE_ALLOC ({ BUILD_BUG(); 0; }) #define THP_FILE_FALLBACK ({ BUILD_BUG(); 0; }) +#define THP_FILE_FALLBACK_CHARGE ({ BUILD_BUG(); 0; }) #define THP_FILE_MAPPED ({ BUILD_BUG(); 0; }) #endif diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 0f9389f9d1f8..0080e8df18ef 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -597,6 +597,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { put_page(page); count_vm_event(THP_FAULT_FALLBACK); + count_vm_event(THP_FAULT_FALLBACK_CHARGE); return VM_FAULT_FALLBACK; } @@ -1446,6 +1447,7 @@ alloc: put_page(page); ret |= VM_FAULT_FALLBACK; count_vm_event(THP_FAULT_FALLBACK); + count_vm_event(THP_FAULT_FALLBACK_CHARGE); goto out; } diff --git a/mm/shmem.c b/mm/shmem.c index 8160d0762bf5..b48ac3806f8f 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1871,8 +1871,10 @@ alloc_nohuge: error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg, PageTransHuge(page)); if (error) { - if (PageTransHuge(page)) + if (PageTransHuge(page)) { count_vm_event(THP_FILE_FALLBACK); + count_vm_event(THP_FILE_FALLBACK_CHARGE); + } goto unacct; } error = shmem_add_to_page_cache(page, mapping, hindex, diff --git a/mm/vmstat.c b/mm/vmstat.c index ebc1dcaa0539..96d21a792b57 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1256,10 +1256,12 @@ const char * const vmstat_text[] = { #ifdef CONFIG_TRANSPARENT_HUGEPAGE "thp_fault_alloc", "thp_fault_fallback", + "thp_fault_fallback_charge", "thp_collapse_alloc", "thp_collapse_alloc_failed", "thp_file_alloc", "thp_file_fallback", + "thp_file_fallback_charge", "thp_file_mapped", "thp_split_page", "thp_split_page_failed", -- 2.39.2