[PATCH 11/13] mm: meminit: Free pages in large chunks where possible

From: Mel Gorman
Date: Wed Apr 22 2015 - 13:09:18 EST


Parallel struct page frees pages one at a time. Try free pages as single
large pages where possible.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/page_alloc.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6b2f6c21b70f..8d3fd13a09c9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1085,6 +1085,20 @@ void __defer_init __free_pages_bootmem(struct page *page, unsigned long pfn,
}

#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+void __defermem_init deferred_free_range(struct page *page, unsigned long pfn,
+ int nr_pages)
+{
+ int i;
+
+ if (nr_pages == MAX_ORDER_NR_PAGES && (pfn & (MAX_ORDER_NR_PAGES-1)) == 0) {
+ __free_pages_boot_core(page, pfn, MAX_ORDER-1);
+ return;
+ }
+
+ for (i = 0; i < nr_pages; i++, page++, pfn++)
+ __free_pages_boot_core(page, pfn, 0);
+}
+
/* Initialise remaining memory on a node */
void __defermem_init deferred_init_memmap(int nid)
{
@@ -1111,6 +1125,9 @@ void __defermem_init deferred_init_memmap(int nid)
for_each_mem_pfn_range(i, nid, &walk_start, &walk_end, NULL) {
unsigned long pfn, end_pfn;
struct page *page = NULL;
+ struct page *free_base_page = NULL;
+ unsigned long free_base_pfn = 0;
+ int nr_to_free = 0;

end_pfn = min(walk_end, zone_end_pfn(zone));
pfn = first_init_pfn;
@@ -1121,7 +1138,7 @@ void __defermem_init deferred_init_memmap(int nid)

for (; pfn < end_pfn; pfn++) {
if (!pfn_valid_within(pfn))
- continue;
+ goto free_range;

/*
* Ensure pfn_valid is checked every
@@ -1130,30 +1147,49 @@ void __defermem_init deferred_init_memmap(int nid)
if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
if (!pfn_valid(pfn)) {
page = NULL;
- continue;
+ goto free_range;
}
}

if (!meminit_pfn_in_nid(pfn, nid, &nid_init_state)) {
page = NULL;
- continue;
+ goto free_range;
}

/* Minimise pfn page lookups and scheduler checks */
if (page && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) {
page++;
} else {
+ deferred_free_range(free_base_page,
+ free_base_pfn, nr_to_free);
+ free_base_page = NULL;
+ free_base_pfn = nr_to_free = 0;
+
page = pfn_to_page(pfn);
cond_resched();
}

if (page->flags) {
VM_BUG_ON(page_zone(page) != zone);
- continue;
+ goto free_range;
}

__init_single_page(page, pfn, zid, nid);
- __free_pages_boot_core(page, pfn, 0);
+ if (!free_base_page) {
+ free_base_page = page;
+ free_base_pfn = pfn;
+ nr_to_free = 0;
+ }
+ nr_to_free++;
+
+ /* Where possible, batch up pages for a single free */
+ continue;
+free_range:
+ /* Free the current block of pages to allocator */
+ if (free_base_page)
+ deferred_free_range(free_base_page, free_base_pfn, nr_to_free);
+ free_base_page = NULL;
+ free_base_pfn = nr_to_free = 0;
}
first_init_pfn = max(end_pfn, first_init_pfn);
}
--
2.1.2

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