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* [patch] mm, thp: track fallbacks due to failed memcg charges separately
@ 2020-02-18  5:41 David Rientjes
  2020-02-18  8:26 ` Kirill A. Shutemov
                   ` (2 more replies)
  0 siblings, 3 replies; 16+ messages in thread
From: David Rientjes @ 2020-02-18  5:41 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Kirill A. Shutemov, Mike Rapoport, Jeremy Cline, linux-kernel, linux-mm

The thp_fault_fallback stat in either /proc/vmstat is 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 a new field,
thp_fault_fallback_charge, which is incremented only when the mem cgroup
charge fails.

This distinguishes between faults that want to be backed by hugepages but
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 <rientjes@google.com>
---
 Documentation/admin-guide/mm/transhuge.rst | 5 +++++
 include/linux/vm_event_item.h              | 1 +
 mm/huge_memory.c                           | 2 ++
 mm/vmstat.c                                | 1 +
 4 files changed, 9 insertions(+)

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
--- 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 through 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
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -73,6 +73,7 @@ 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,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- 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;
 	}
 
@@ -1406,6 +1407,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
 			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/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1254,6 +1254,7 @@ 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",


^ permalink raw reply	[flat|nested] 16+ messages in thread
* [patch 1/2] mm, shmem: add vmstat for hugepage fallback
@ 2020-03-06 22:22 David Rientjes
  2020-03-06 22:22 ` [patch 2/2] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
  0 siblings, 1 reply; 16+ messages in thread
From: David Rientjes @ 2020-03-06 22:22 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Yang Shi, Kirill A. Shutemov, Kirill A. Shutemov, Mike Rapoport,
	Jeremy Cline, Linux Kernel Mailing List, Linux MM

The existing thp_fault_fallback indicates when thp attempts to allocate a
hugepage but fails, or if the hugepage cannot be charged to the mem cgroup
hierarchy.

Extend this to shmem as well.  Adds a new thp_file_fallback to complement
thp_file_alloc that gets incremented when a hugepage is attempted to be
allocated but fails, or if it cannot be charged to the mem cgroup
hierarchy.

Additionally, remove the check for CONFIG_TRANSPARENT_HUGE_PAGECACHE from
shmem_alloc_hugepage() since it is only called with this configuration
option.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 Documentation/admin-guide/mm/transhuge.rst |  4 ++++
 include/linux/vm_event_item.h              |  2 ++
 mm/shmem.c                                 | 10 ++++++----
 mm/vmstat.c                                |  1 +
 4 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -319,6 +319,10 @@ thp_file_alloc
 	is incremented every time a file huge page is successfully
 	allocated.
 
+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_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
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -76,6 +76,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		THP_COLLAPSE_ALLOC,
 		THP_COLLAPSE_ALLOC_FAILED,
 		THP_FILE_ALLOC,
+		THP_FILE_FALLBACK,
 		THP_FILE_MAPPED,
 		THP_SPLIT_PAGE,
 		THP_SPLIT_PAGE_FAILED,
@@ -115,6 +116,7 @@ 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_MAPPED ({ BUILD_BUG(); 0; })
 #endif
 
diff --git a/mm/shmem.c b/mm/shmem.c
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1472,9 +1472,6 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
 	pgoff_t hindex;
 	struct page *page;
 
-	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
-		return NULL;
-
 	hindex = round_down(index, HPAGE_PMD_NR);
 	if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
 								XA_PRESENT))
@@ -1486,6 +1483,8 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
 	shmem_pseudo_vma_destroy(&pvma);
 	if (page)
 		prep_transhuge_page(page);
+	else
+		count_vm_event(THP_FILE_FALLBACK);
 	return page;
 }
 
@@ -1871,8 +1870,11 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 
 	error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg,
 					    PageTransHuge(page));
-	if (error)
+	if (error) {
+		if (PageTransHuge(page))
+			count_vm_event(THP_FILE_FALLBACK);
 		goto unacct;
+	}
 	error = shmem_add_to_page_cache(page, mapping, hindex,
 					NULL, gfp & GFP_RECLAIM_MASK);
 	if (error) {
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1257,6 +1257,7 @@ const char * const vmstat_text[] = {
 	"thp_collapse_alloc",
 	"thp_collapse_alloc_failed",
 	"thp_file_alloc",
+	"thp_file_fallback",
 	"thp_file_mapped",
 	"thp_split_page",
 	"thp_split_page_failed",


^ permalink raw reply	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2020-03-09 15:48 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-02-18  5:41 [patch] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
2020-02-18  8:26 ` Kirill A. Shutemov
2020-02-19  1:59   ` David Rientjes
2020-02-18  9:34 ` Mike Rapoport
2020-02-19  2:29 ` [patch 1/2] mm, shmem: add thp fault alloc and fallback stats David Rientjes
2020-02-19  2:29   ` [patch 2/2] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
2020-02-19  8:23     ` Mike Rapoport
2020-02-19  3:22   ` [patch 1/2] mm, shmem: add thp fault alloc and fallback stats Yang Shi
2020-02-19  3:44     ` David Rientjes
2020-02-19 17:01       ` Yang Shi
2020-02-20 13:12         ` Kirill A. Shutemov
2020-03-06 17:23           ` Yang Shi
2020-03-06 21:27             ` David Rientjes
2020-03-06 22:22 [patch 1/2] mm, shmem: add vmstat for hugepage fallback David Rientjes
2020-03-06 22:22 ` [patch 2/2] mm, thp: track fallbacks due to failed memcg charges separately David Rientjes
2020-03-07  4:13   ` Yang Shi
2020-03-09 15:48   ` Kirill A. Shutemov

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