Commit 44048d70 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Revert "Bias the placement of kernel pages at lower PFNs"

This reverts commit 5adc5be7

.

Alexey Dobriyan reports that it causes huge slowdowns under some loads,
in his case a "mkfs.ext2" on a 30G partition.  With the placement bias,
the mkfs took over four minutes, with it reverted it's back to about ten
seconds for Alexey.
Reported-and-tested-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e6a5c27f
......@@ -749,23 +749,6 @@ int move_freepages_block(struct zone *zone, struct page *page, int migratetype)
return move_freepages(zone, start_page, end_page, migratetype);
}
/* Return the page with the lowest PFN in the list */
static struct page *min_page(struct list_head *list)
{
unsigned long min_pfn = -1UL;
struct page *min_page = NULL, *page;;
list_for_each_entry(page, list, lru) {
unsigned long pfn = page_to_pfn(page);
if (pfn < min_pfn) {
min_pfn = pfn;
min_page = page;
}
}
return min_page;
}
/* Remove an element from the buddy allocator from the fallback list */
static struct page *__rmqueue_fallback(struct zone *zone, int order,
int start_migratetype)
......@@ -789,11 +772,8 @@ static struct page *__rmqueue_fallback(struct zone *zone, int order,
if (list_empty(&area->free_list[migratetype]))
continue;
/* Bias kernel allocations towards low pfns */
page = list_entry(area->free_list[migratetype].next,
struct page, lru);
if (unlikely(start_migratetype != MIGRATE_MOVABLE))
page = min_page(&area->free_list[migratetype]);
area->nr_free--;
/*
......
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