Commit 58f17117 authored Sep 08, 2015 by Sergey Senozhatsky Committed by Linus Torvalds Sep 08, 2015

zsmalloc: partial page ordering within a fullness_list



We want to see more ZS_FULL pages and less ZS_ALMOST_{FULL, EMPTY}
pages.  Put a page with higher ->inuse count first within its
->fullness_list, which will give us better chances to fill up this page
with new objects (find_get_zspage() return ->fullness_list head for new
object allocation), so some zspages will become ZS_ALMOST_FULL/ZS_FULL
quicker.

It performs a trivial and cheap ->inuse compare which does not slow down
zsmalloc and in the worst case keeps the list pages in no particular
order.

A more expensive solution could sort fullness_list by ->inuse count.

[minchan@kernel.org: code adjustments]
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ab9d306d

mm/zsmalloc.c

+14 −5

Original line number	Diff line number	Diff line
		@@ -643,13 +643,22 @@ static void insert_zspage(struct page page, struct size_class class,
		if (fullness >= _ZS_NR_FULLNESS_GROUPS)
		return;

		zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
		CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);

		head = &class->fullness_list[fullness];
		if (*head)
		list_add_tail(&page->lru, &(*head)->lru);
		if (!*head) {
		*head = page;
		return;
		}

		/*
		* We want to see more ZS_FULL pages and less almost
		* empty/full. Put pages with higher ->inuse first.
		*/
		list_add_tail(&page->lru, &(*head)->lru);
		if (page->inuse >= (*head)->inuse)
		*head = page;
		zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
		CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
		}

		/*

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