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Groups > linux.kernel > #1375571 > unrolled thread

[PATCH 00/21] Optimise page alloc/free fast paths

Started byMel Gorman <mgorman@techsingularity.net>
First post2016-04-11 10:20 +0200
Last post2016-04-11 10:40 +0200
Articles 3 on this page of 23 — 1 participant

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  [PATCH 00/21] Optimise page alloc/free fast paths Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 08/22] mm, page_alloc: Convert alloc_flags to unsigned Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 04/22] mm, page_alloc: Inline zone_statistics Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 21/22] cpuset: use static key better and convert to new API Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 11/22] mm, page_alloc: Remove unnecessary initialisation in get_page_from_freelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 14/22] mm, page_alloc: Simplify last cpupid reset Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 13/22] mm, page_alloc: Remove redundant check for empty zonelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 09/22] mm, page_alloc: Convert nr_fair_skipped to bool Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 15/22] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 20/22] mm, page_alloc: Check multiple page fields with a single branch Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 12/22] mm, page_alloc: Remove unnecessary initialisation from __alloc_pages_nodemask() Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 19/22] mm, page_alloc: Avoid looking up the first zone in a zonelist twice Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 05/22] mm, page_alloc: Inline the fast path of the zonelist iterator Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 02/22] mm, page_alloc: Use new PageAnonHead helper in the free page fast path Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 16/22] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 17/22] mm, page_alloc: Reduce cost of fair zone allocation policy retry Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:20 +0200
    [PATCH 18/22] mm, page_alloc: Shortcut watermark checks for order-0 pages Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:30 +0200
    Re: [PATCH 00/21] Optimise page alloc/free fast paths Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:30 +0200
    [PATCH 06/22] mm, page_alloc: Use __dec_zone_state for order-0 page allocation Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:30 +0200
    [PATCH 10/22] mm, page_alloc: Remove unnecessary local variable in get_page_from_freelist Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:30 +0200
    [PATCH 07/22] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:30 +0200
    [PATCH 01/22] mm, page_alloc: Only check PageCompound for high-order pages Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:40 +0200
    [PATCH 03/22] mm, page_alloc: Reduce branches in zone_statistics Mel Gorman <mgorman@techsingularity.net> - 2016-04-11 10:40 +0200

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#1375608 — [PATCH 07/22] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations

FromMel Gorman <mgorman@techsingularity.net>
Date2016-04-11 10:30 +0200
Subject[PATCH 07/22] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations
Message-ID<rmFon-2Ng-35@gated-at.bofh.it>
In reply to#1375571
Pageblocks have an associated bitmap to store migrate types and whether
the pageblock should be skipped during compaction. The bitmap may be
associated with a memory section or a zone but the zone is looked up
unconditionally. The compiler should optimise this away automatically so
this is a cosmetic patch only in many cases.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/page_alloc.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ab16560b76e6..d00847bb1612 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6759,23 +6759,23 @@ void *__init alloc_large_system_hash(const char *tablename,
 }
 
 /* Return a pointer to the bitmap storing bits affecting a block of pages */
-static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
+static inline unsigned long *get_pageblock_bitmap(struct page *page,
 							unsigned long pfn)
 {
 #ifdef CONFIG_SPARSEMEM
 	return __pfn_to_section(pfn)->pageblock_flags;
 #else
-	return zone->pageblock_flags;
+	return page_zone(page)->pageblock_flags;
 #endif /* CONFIG_SPARSEMEM */
 }
 
-static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
+static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
 {
 #ifdef CONFIG_SPARSEMEM
 	pfn &= (PAGES_PER_SECTION-1);
 	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 #else
-	pfn = pfn - round_down(zone->zone_start_pfn, pageblock_nr_pages);
+	pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
 	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 #endif /* CONFIG_SPARSEMEM */
 }
@@ -6793,14 +6793,12 @@ unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
 					unsigned long end_bitidx,
 					unsigned long mask)
 {
-	struct zone *zone;
 	unsigned long *bitmap;
 	unsigned long bitidx, word_bitidx;
 	unsigned long word;
 
-	zone = page_zone(page);
-	bitmap = get_pageblock_bitmap(zone, pfn);
-	bitidx = pfn_to_bitidx(zone, pfn);
+	bitmap = get_pageblock_bitmap(page, pfn);
+	bitidx = pfn_to_bitidx(page, pfn);
 	word_bitidx = bitidx / BITS_PER_LONG;
 	bitidx &= (BITS_PER_LONG-1);
 
@@ -6822,20 +6820,18 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
 					unsigned long end_bitidx,
 					unsigned long mask)
 {
-	struct zone *zone;
 	unsigned long *bitmap;
 	unsigned long bitidx, word_bitidx;
 	unsigned long old_word, word;
 
 	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
 
-	zone = page_zone(page);
-	bitmap = get_pageblock_bitmap(zone, pfn);
-	bitidx = pfn_to_bitidx(zone, pfn);
+	bitmap = get_pageblock_bitmap(page, pfn);
+	bitidx = pfn_to_bitidx(page, pfn);
 	word_bitidx = bitidx / BITS_PER_LONG;
 	bitidx &= (BITS_PER_LONG-1);
 
-	VM_BUG_ON_PAGE(!zone_spans_pfn(zone, pfn), page);
+	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
 
 	bitidx += end_bitidx;
 	mask <<= (BITS_PER_LONG - bitidx - 1);
-- 
2.6.4

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#1375610 — [PATCH 01/22] mm, page_alloc: Only check PageCompound for high-order pages

FromMel Gorman <mgorman@techsingularity.net>
Date2016-04-11 10:40 +0200
Subject[PATCH 01/22] mm, page_alloc: Only check PageCompound for high-order pages
Message-ID<rmFy2-2Qu-5@gated-at.bofh.it>
In reply to#1375571
order-0 pages by definition cannot be compound so avoid the check in the
fast path for those pages.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/page_alloc.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 59de90d5d3a3..5d205bcfe10d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1024,24 +1024,33 @@ void __meminit reserve_bootmem_region(unsigned long start, unsigned long end)
 
 static bool free_pages_prepare(struct page *page, unsigned int order)
 {
-	bool compound = PageCompound(page);
-	int i, bad = 0;
+	int bad = 0;
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
-	VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
 
 	trace_mm_page_free(page, order);
 	kmemcheck_free_shadow(page, order);
 	kasan_free_pages(page, order);
 
+	/*
+	 * Check tail pages before head page information is cleared to
+	 * avoid checking PageCompound for order-0 pages.
+	 */
+	if (order) {
+		bool compound = PageCompound(page);
+		int i;
+
+		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
+
+		for (i = 1; i < (1 << order); i++) {
+			if (compound)
+				bad += free_tail_pages_check(page, page + i);
+			bad += free_pages_check(page + i);
+		}
+	}
 	if (PageAnon(page))
 		page->mapping = NULL;
 	bad += free_pages_check(page);
-	for (i = 1; i < (1 << order); i++) {
-		if (compound)
-			bad += free_tail_pages_check(page, page + i);
-		bad += free_pages_check(page + i);
-	}
 	if (bad)
 		return false;
 
-- 
2.6.4

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#1375614 — [PATCH 03/22] mm, page_alloc: Reduce branches in zone_statistics

FromMel Gorman <mgorman@techsingularity.net>
Date2016-04-11 10:40 +0200
Subject[PATCH 03/22] mm, page_alloc: Reduce branches in zone_statistics
Message-ID<rmFy2-2Qu-15@gated-at.bofh.it>
In reply to#1375571
zone_statistics has more branches than it really needs to take an
unlikely GFP flag into account. Reduce the number and annotate
the unlikely flag.

The performance difference on a page allocator microbenchmark is;

                                           4.6.0-rc2                  4.6.0-rc2
                                    nocompound-v1r10           statbranch-v1r10
Min      alloc-odr0-1               417.00 (  0.00%)           419.00 ( -0.48%)
Min      alloc-odr0-2               308.00 (  0.00%)           305.00 (  0.97%)
Min      alloc-odr0-4               253.00 (  0.00%)           250.00 (  1.19%)
Min      alloc-odr0-8               221.00 (  0.00%)           219.00 (  0.90%)
Min      alloc-odr0-16              205.00 (  0.00%)           203.00 (  0.98%)
Min      alloc-odr0-32              199.00 (  0.00%)           195.00 (  2.01%)
Min      alloc-odr0-64              193.00 (  0.00%)           191.00 (  1.04%)
Min      alloc-odr0-128             191.00 (  0.00%)           189.00 (  1.05%)
Min      alloc-odr0-256             200.00 (  0.00%)           198.00 (  1.00%)
Min      alloc-odr0-512             212.00 (  0.00%)           210.00 (  0.94%)
Min      alloc-odr0-1024            219.00 (  0.00%)           216.00 (  1.37%)
Min      alloc-odr0-2048            225.00 (  0.00%)           221.00 (  1.78%)
Min      alloc-odr0-4096            231.00 (  0.00%)           227.00 (  1.73%)
Min      alloc-odr0-8192            234.00 (  0.00%)           232.00 (  0.85%)
Min      alloc-odr0-16384           234.00 (  0.00%)           232.00 (  0.85%)

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/vmstat.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 5e4300482897..2e58ead9bcf5 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -581,17 +581,21 @@ void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
  */
 void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 {
-	if (z->zone_pgdat == preferred_zone->zone_pgdat) {
+	int local_nid = numa_node_id();
+	enum zone_stat_item local_stat = NUMA_LOCAL;
+
+	if (unlikely(flags & __GFP_OTHER_NODE)) {
+		local_stat = NUMA_OTHER;
+		local_nid = preferred_zone->node;
+	}
+
+	if (z->node == local_nid) {
 		__inc_zone_state(z, NUMA_HIT);
+		__inc_zone_state(z, local_stat);
 	} else {
 		__inc_zone_state(z, NUMA_MISS);
 		__inc_zone_state(preferred_zone, NUMA_FOREIGN);
 	}
-	if (z->node == ((flags & __GFP_OTHER_NODE) ?
-			preferred_zone->node : numa_node_id()))
-		__inc_zone_state(z, NUMA_LOCAL);
-	else
-		__inc_zone_state(z, NUMA_OTHER);
 }
 
 /*
-- 
2.6.4

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