From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicolas Saenz Julienne <nsaenzju@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Vlastimil Babka <vbabka@suse.cz>,
Michal Hocko <mhocko@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 2/6] mm/page_alloc: Use only one PCP list for THP-sized allocations
Date: Thu, 12 May 2022 09:50:39 +0100 [thread overview]
Message-ID: <20220512085043.5234-3-mgorman@techsingularity.net> (raw)
In-Reply-To: <20220512085043.5234-1-mgorman@techsingularity.net>
The per_cpu_pages is cache-aligned on a standard x86-64 distribution
configuration but a later patch will add a new field which would push
the structure into the next cache line. Use only one list to store
THP-sized pages on the per-cpu list. This assumes that the vast majority
of THP-sized allocations are GFP_MOVABLE but even if it was another type,
it would not contribute to serious fragmentation that potentially causes
a later THP allocation failure. Align per_cpu_pages on the cacheline
boundary to ensure there is no false cache sharing.
After this patch, the structure sizing is;
struct per_cpu_pages {
int count; /* 0 4 */
int high; /* 4 4 */
int batch; /* 8 4 */
short int free_factor; /* 12 2 */
short int expire; /* 14 2 */
struct list_head lists[13]; /* 16 208 */
/* size: 256, cachelines: 4, members: 6 */
/* padding: 32 */
} __attribute__((__aligned__(64)));
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
---
include/linux/mmzone.h | 11 +++++++----
mm/page_alloc.c | 4 ++--
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 962b14d403e8..abe530748de6 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -358,15 +358,18 @@ enum zone_watermarks {
};
/*
- * One per migratetype for each PAGE_ALLOC_COSTLY_ORDER plus one additional
- * for pageblock size for THP if configured.
+ * One per migratetype for each PAGE_ALLOC_COSTLY_ORDER. One additional list
+ * for THP which will usually be GFP_MOVABLE. Even if it is another type,
+ * it should not contribute to serious fragmentation causing THP allocation
+ * failures.
*/
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define NR_PCP_THP 1
#else
#define NR_PCP_THP 0
#endif
-#define NR_PCP_LISTS (MIGRATE_PCPTYPES * (PAGE_ALLOC_COSTLY_ORDER + 1 + NR_PCP_THP))
+#define NR_LOWORDER_PCP_LISTS (MIGRATE_PCPTYPES * (PAGE_ALLOC_COSTLY_ORDER + 1))
+#define NR_PCP_LISTS (NR_LOWORDER_PCP_LISTS + NR_PCP_THP)
/*
* Shift to encode migratetype and order in the same integer, with order
@@ -392,7 +395,7 @@ struct per_cpu_pages {
/* Lists of pages, one per migrate type stored on the pcp-lists */
struct list_head lists[NR_PCP_LISTS];
-};
+} ____cacheline_aligned_in_smp;
struct per_cpu_zonestat {
#ifdef CONFIG_SMP
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f58f85fdb05f..5851ee88a89c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -648,7 +648,7 @@ static inline unsigned int order_to_pindex(int migratetype, int order)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (order > PAGE_ALLOC_COSTLY_ORDER) {
VM_BUG_ON(order != pageblock_order);
- base = PAGE_ALLOC_COSTLY_ORDER + 1;
+ return NR_LOWORDER_PCP_LISTS;
}
#else
VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
@@ -662,7 +662,7 @@ static inline int pindex_to_order(unsigned int pindex)
int order = pindex / MIGRATE_PCPTYPES;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- if (order > PAGE_ALLOC_COSTLY_ORDER)
+ if (pindex == NR_LOWORDER_PCP_LISTS)
order = pageblock_order;
#else
VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
--
2.34.1
next prev parent reply other threads:[~2022-05-12 8:51 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 8:50 [PATCH 0/6] Drain remote per-cpu directly v3 Mel Gorman
2022-05-12 8:50 ` [PATCH 1/6] mm/page_alloc: Add page->buddy_list and page->pcp_list Mel Gorman
2022-05-13 11:59 ` Nicolas Saenz Julienne
2022-05-19 9:36 ` Vlastimil Babka
2022-05-12 8:50 ` Mel Gorman [this message]
2022-05-19 9:45 ` [PATCH 2/6] mm/page_alloc: Use only one PCP list for THP-sized allocations Vlastimil Babka
2022-05-12 8:50 ` [PATCH 3/6] mm/page_alloc: Split out buddy removal code from rmqueue into separate helper Mel Gorman
2022-05-13 12:01 ` Nicolas Saenz Julienne
2022-05-19 9:52 ` Vlastimil Babka
2022-05-23 16:09 ` Qais Yousef
2022-05-24 11:55 ` Mel Gorman
2022-05-25 11:23 ` Qais Yousef
2022-05-12 8:50 ` [PATCH 4/6] mm/page_alloc: Remove unnecessary page == NULL check in rmqueue Mel Gorman
2022-05-13 12:03 ` Nicolas Saenz Julienne
2022-05-19 10:57 ` Vlastimil Babka
2022-05-19 12:13 ` Mel Gorman
2022-05-19 12:26 ` Vlastimil Babka
2022-05-12 8:50 ` [PATCH 5/6] mm/page_alloc: Protect PCP lists with a spinlock Mel Gorman
2022-05-13 12:22 ` Nicolas Saenz Julienne
2022-05-12 8:50 ` [PATCH 6/6] mm/page_alloc: Remotely drain per-cpu lists Mel Gorman
2022-05-12 19:37 ` Andrew Morton
2022-05-13 15:04 ` Mel Gorman
2022-05-13 15:19 ` Nicolas Saenz Julienne
2022-05-13 18:23 ` Mel Gorman
2022-05-17 12:57 ` Mel Gorman
2022-05-12 19:43 ` [PATCH 0/6] Drain remote per-cpu directly v3 Andrew Morton
2022-05-13 14:23 ` Mel Gorman
2022-05-13 19:38 ` Andrew Morton
2022-05-16 10:53 ` Mel Gorman
2022-05-13 12:24 ` Nicolas Saenz Julienne
2022-05-17 23:35 ` Qian Cai
2022-05-18 12:51 ` Mel Gorman
2022-05-18 16:27 ` Qian Cai
2022-05-18 17:15 ` Paul E. McKenney
2022-05-19 13:29 ` Qian Cai
2022-05-19 19:15 ` Paul E. McKenney
2022-05-19 21:05 ` Qian Cai
2022-05-19 21:29 ` Paul E. McKenney
2022-05-18 17:26 ` Marcelo Tosatti
2022-05-18 17:44 ` Marcelo Tosatti
2022-05-18 18:01 ` Nicolas Saenz Julienne
2022-05-26 17:19 ` Qian Cai
2022-05-27 8:39 ` Mel Gorman
2022-05-27 12:58 ` Qian Cai
-- strict thread matches above, loose matches on Subject: below --
2022-05-09 13:07 [RFC PATCH 0/6] Drain remote per-cpu directly v2 Mel Gorman
2022-05-09 13:08 ` [PATCH 2/6] mm/page_alloc: Use only one PCP list for THP-sized allocations Mel Gorman
2022-04-20 9:59 [RFC PATCH 0/6] Drain remote per-cpu directly Mel Gorman
2022-04-20 9:59 ` [PATCH 2/6] mm/page_alloc: Use only one PCP list for THP-sized allocations Mel Gorman
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