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From: Joao Martins <joao.m.martins@oracle.com>
To: linux-mm@kvack.org
Cc: linux-nvdimm@lists.01.org, Matthew Wilcox <willy@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Muchun Song <songmuchun@bytedance.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Joao Martins <joao.m.martins@oracle.com>
Subject: [PATCH v1 09/11] mm/page_alloc: reuse tail struct pages for compound pagemaps
Date: Thu, 25 Mar 2021 23:09:36 +0000	[thread overview]
Message-ID: <20210325230938.30752-10-joao.m.martins@oracle.com> (raw)
In-Reply-To: <20210325230938.30752-1-joao.m.martins@oracle.com>

When a pgmap @align is set, all pages are mapped at a given huge page
alignment and thus uses compound pages to describe them as opposed to a
struct per 4K.

With @align > PAGE_SIZE and when struct pages are stored in ram
(!altmap) most tail pages are reused. Consequently, the amount of unique
struct pages is a lot smaller that the total amount of struct pages
being mapped.

When struct pages are initialize in memmap_init_zone_device, make
sure that only unique struct pages are initialized i.e. the first 2
4K pages per @align which means 128 struct pages, instead of 32768 for
2M @align or 262144 for a 1G @align.

Keep old behaviour with altmap given that it doesn't support reusal
of tail vmemmap areas.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 mm/page_alloc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3a77f9e43f3a..948dfad6754b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6277,6 +6277,8 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
 	}
 }
 
+#define MEMMAP_NR_PAGES	(2 * (PAGE_SIZE/sizeof(struct page)))
+
 void __ref memmap_init_zone_device(struct zone *zone,
 				   unsigned long start_pfn,
 				   unsigned long nr_pages,
@@ -6287,6 +6289,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 	struct vmem_altmap *altmap = pgmap_altmap(pgmap);
 	unsigned int pfn_align = pgmap_pfn_align(pgmap);
 	unsigned int order_align = order_base_2(pfn_align);
+	unsigned long ntails = min_t(unsigned long, pfn_align, MEMMAP_NR_PAGES);
 	unsigned long zone_idx = zone_idx(zone);
 	unsigned long start = jiffies;
 	int nid = pgdat->node_id;
@@ -6302,6 +6305,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 	if (altmap) {
 		start_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
 		nr_pages = end_pfn - start_pfn;
+		ntails = pfn_align;
 	}
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn += pfn_align) {
@@ -6315,7 +6319,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 
 		__SetPageHead(page);
 
-		for (i = 1; i < pfn_align; i++) {
+		for (i = 1; i < ntails; i++) {
 			__init_zone_device_page(page + i, pfn + i, zone_idx,
 						nid, pgmap);
 			prep_compound_tail(page, i);
-- 
2.17.1
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  parent reply	other threads:[~2021-03-25 23:10 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-25 23:09 [PATCH v1 00/11] mm, sparse-vmemmap: Introduce " Joao Martins
2021-03-25 23:09 ` [PATCH v1 01/11] memory-failure: fetch compound_head after pgmap_pfn_valid() Joao Martins
2021-03-25 23:09 ` [PATCH v1 02/11] mm/page_alloc: split prep_compound_page into head and tail subparts Joao Martins
2021-03-25 23:09 ` [PATCH v1 03/11] mm/page_alloc: refactor memmap_init_zone_device() page init Joao Martins
2021-03-25 23:09 ` [PATCH v1 04/11] mm/memremap: add ZONE_DEVICE support for compound pages Joao Martins
     [not found]   ` <CAPcyv4gs_rHL7FPqyQEb3yT4jrv8Wo_xA2ojKsppoBfmDocq8A@mail.gmail.com>
     [not found]     ` <cd1c9849-8660-dbdc-718a-aa4ba5d48c01@oracle.com>
     [not found]       ` <CAPcyv4jG8+S6xJyp=1S2=dpit0Hs2+HgGwpWeRROCRuJnQYAxQ@mail.gmail.com>
     [not found]         ` <56a3e271-4ef8-ba02-639e-fd7fe7de7e36@oracle.com>
     [not found]           ` <8c922a58-c901-1ad9-5d19-1182bd6dea1e@oracle.com>
     [not found]             ` <CAPcyv4j_PdzytEeabe95FrUiNVNobdJRvUE9M9j0krKQ1defBg@mail.gmail.com>
     [not found]               ` <e22ef769-5eb2-1812-497f-6d069d632cd0@oracle.com>
2021-06-07 21:00                 ` Joao Martins
2021-06-07 21:57                   ` Dan Williams
2021-03-25 23:09 ` [PATCH v1 05/11] mm/sparse-vmemmap: add a pgmap argument to section activation Joao Martins
2021-03-25 23:09 ` [PATCH v1 06/11] mm/sparse-vmemmap: refactor vmemmap_populate_basepages() Joao Martins
2021-03-25 23:09 ` [PATCH v1 07/11] mm/sparse-vmemmap: populate compound pagemaps Joao Martins
2021-03-25 23:09 ` [PATCH v1 08/11] mm/sparse-vmemmap: use hugepages for PUD " Joao Martins
2021-03-25 23:09 ` Joao Martins [this message]
     [not found]   ` <CAPcyv4gtSqfmuAaX9cs63OvLkf-h4B_5fPiEnM9p9cqLZztXpg@mail.gmail.com>
2021-06-07 13:48     ` [PATCH v1 09/11] mm/page_alloc: reuse tail struct pages for " Joao Martins
2021-06-07 19:32       ` Dan Williams
2021-06-14 18:41         ` Joao Martins
2021-06-14 23:07           ` Dan Williams
2021-03-25 23:09 ` [PATCH v1 10/11] device-dax: compound pagemap support Joao Martins
     [not found]   ` <CAPcyv4jeY0K7ciWeCLjxXmiWs7NNeM-_zEdZ2XAdYnyZc9PvWA@mail.gmail.com>
2021-06-07 13:59     ` Joao Martins
2021-03-25 23:09 ` [PATCH v1 11/11] mm/gup: grab head page refcount once for group of subpages Joao Martins
2021-06-02  1:05   ` Dan Williams
2021-06-07 15:21     ` Joao Martins
2021-06-07 19:22       ` Dan Williams
2021-04-01  9:38 ` [PATCH v1 00/11] mm, sparse-vmemmap: Introduce compound pagemaps Joao Martins

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