The patch titled
Subject: mm: provide more accurate estimation of pages occupied by memmap
has been removed from the -mm tree. Its filename was
mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
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.
[akpm@xxxxxxxxxxxxxxxxxxxx: mark calc_memmap_size __paging_init]
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@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>
Tested-by: 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
@@ -4489,6 +4489,26 @@ void __init set_pageblock_order(void)
#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+static unsigned long __paginginit 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
@@ -4523,8 +4543,7 @@ 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)
@@ -4545,6 +4564,9 @@ 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
origin.patch
linux-next.patch
x86-fix-the-argument-passed-to-sync_global_pgds.patch
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