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Commit d8a8e1f0 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

thp, vmstat: implement HZP_ALLOC and HZP_ALLOC_FAILED events 



hzp_alloc is incremented every time a huge zero page is successfully
	allocated. It includes allocations which where dropped due
	race with other allocation. Note, it doesn't count every map
	of the huge zero page, only its allocation.

hzp_alloc_failed is incremented if kernel fails to allocate huge zero
	page and falls back to using small pages.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 97ae1749

Documentation/vm/transhuge.txt

+8 −0
Original line number Diff line number Diff line
@@ -197,6 +197,14 @@ thp_split is incremented every time a huge page is split into base 
	pages. This can happen for a variety of reasons but a common

	reason is that a huge page is old and is being reclaimed.



thp_zero_page_alloc is incremented every time a huge zero page is

	successfully allocated. It includes allocations which where

	dropped due race with other allocation. Note, it doesn't count

	every map of the huge zero page, only its allocation.



thp_zero_page_alloc_failed is incremented if kernel fails to allocate

	huge zero page and falls back to using small pages.



As the system ages, allocating huge pages may be expensive as the

system uses memory compaction to copy data around memory to free a

huge page for use. There are some counters in /proc/vmstat to help

include/linux/vm_event_item.h

+2 −0
Original line number Diff line number Diff line
@@ -58,6 +58,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, 
		THP_COLLAPSE_ALLOC,

		THP_COLLAPSE_ALLOC_FAILED,

		THP_SPLIT,

		THP_ZERO_PAGE_ALLOC,

		THP_ZERO_PAGE_ALLOC_FAILED,

#endif

		NR_VM_EVENT_ITEMS

};

mm/huge_memory.c

+4 −1
Original line number Diff line number Diff line
@@ -184,8 +184,11 @@ retry: 


	zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,

			HPAGE_PMD_ORDER);

	if (!zero_page)

	if (!zero_page) {

		count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);

		return 0;

	}

	count_vm_event(THP_ZERO_PAGE_ALLOC);

	preempt_disable();

	if (cmpxchg(&huge_zero_pfn, 0, page_to_pfn(zero_page))) {

		preempt_enable();

mm/vmstat.c

+2 −0
Original line number Diff line number Diff line
@@ -801,6 +801,8 @@ const char * const vmstat_text[] = { 
	"thp_collapse_alloc",

	"thp_collapse_alloc_failed",

	"thp_split",

	"thp_zero_page_alloc",

	"thp_zero_page_alloc_failed",

#endif



#endif /* CONFIG_VM_EVENTS_COUNTERS */