The patch titled
Subject: mm: provide more accurate estimation of pages occupied by memmap
has been added to the -mm tree. Its filename is
mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap.patch
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From: Jiang Liu <liuj97@xxxxxxxxx>
Subject: mm: provide more accurate estimation of pages occupied by memmap
If SPARSEMEM is enabled, it won't build page structures for non-existing
pages (holes) within a zone, so provide a more accurate estimation of
pages occupied by memmap if there are bigger holes within the zone.
And pages for highmem zones' memmap will be allocated from lowmem, so
charge nr_kernel_pages for that.
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Maciej Rutecki <maciej.rutecki@xxxxxxxxx>
Cc: Chris Clayton <chris2553@xxxxxxxxxxxxxx>
Cc: "Rafael J . Wysocki" <rjw@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Jianguo Wu <wujianguo@xxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff -puN mm/page_alloc.c~mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap mm/page_alloc.c
--- a/mm/page_alloc.c~mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap
+++ a/mm/page_alloc.c
@@ -4526,6 +4526,26 @@ void __init set_pageblock_order(void)
#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+static unsigned long calc_memmap_size(unsigned long spanned_pages,
+ unsigned long present_pages)
+{
+ unsigned long pages = spanned_pages;
+
+ /*
+ * Provide a more accurate estimation if there are holes within
+ * the zone and SPARSEMEM is in use. If there are holes within the
+ * zone, each populated memory region may cost us one or two extra
+ * memmap pages due to alignment because memmap pages for each
+ * populated regions may not naturally algined on page boundary.
+ * So the (present_pages >> 4) heuristic is a tradeoff for that.
+ */
+ if (spanned_pages > present_pages + (present_pages >> 4) &&
+ IS_ENABLED(CONFIG_SPARSEMEM))
+ pages = present_pages;
+
+ return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT;
+}
+
/*
* Set up the zone data structures:
* - mark all pages reserved
@@ -4560,8 +4580,7 @@ static void __paginginit free_area_init_
* is used by this zone for memmap. This affects the watermark
* and per-cpu initialisations
*/
- memmap_pages =
- PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT;
+ memmap_pages = calc_memmap_size(size, realsize);
if (freesize >= memmap_pages) {
freesize -= memmap_pages;
if (memmap_pages)
@@ -4582,6 +4601,9 @@ static void __paginginit free_area_init_
if (!is_highmem_idx(j))
nr_kernel_pages += freesize;
+ /* Charge for highmem memmap if there are enough kernel pages */
+ else if (nr_kernel_pages > memmap_pages * 2)
+ nr_kernel_pages -= memmap_pages;
nr_all_pages += freesize;
zone->spanned_pages = size;
_
Patches currently in -mm which might be from liuj97@xxxxxxxxx are
linux-next.patch
x86-fix-the-argument-passed-to-sync_global_pgds.patch
memory-hotplug-suppress-device-memoryx-does-not-have-a-release-function-warning.patch
memory-hotplug-skip-hwpoisoned-page-when-offlining-pages.patch
memory-hotplug-update-mce_bad_pages-when-removing-the-memory.patch
memory-hotplug-update-mce_bad_pages-when-removing-the-memory-fix.patch
memory-hotplug-auto-offline-page_cgroup-when-onlining-memory-block-failed.patch
memory-hotplug-fix-nr_free_pages-mismatch.patch
numa-convert-static-memory-to-dynamically-allocated-memory-for-per-node-device.patch
memory-hotplug-suppress-device-nodex-does-not-have-a-release-function-warning.patch
memory-hotplug-mm-sparsec-clear-the-memory-to-store-struct-page.patch
memory-hotplug-allocate-zones-pcp-before-onlining-pages.patch
memory-hotplug-allocate-zones-pcp-before-onlining-pages-fix-2.patch
mm-introduce-new-field-managed_pages-to-struct-zone.patch
mm-introduce-new-field-managed_pages-to-struct-zone-fix.patch
mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap.patch
mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap-fix.patch
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