Commit 146500e9 authored Jan 31, 2018 by Matthew Wilcox Committed by Linus Torvalds Jan 31, 2018

mm: get 7% more pages in a pagevec

We don't have to use an entire 'long' for the number of elements in the
pagevec; we know it's a number between 0 and 14 (now 15).  So we can
store it in a char, and then the bool packs next to it and we still have
two or six bytes of padding for more elements in the header.  That gives
us space to cram in an extra page.

Link: http://lkml.kernel.org/r/20171206022521.GM26021@bombadil.infradead.org


Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 977fbdcd

include/linux/pagevec.h

+3 −3

Original line number	Diff line number	Diff line
		@@ -9,14 +9,14 @@
		#ifndef _LINUX_PAGEVEC_H
		#define _LINUX_PAGEVEC_H

		/* 14 pointers + two long's align the pagevec structure to a power of two */
		#define PAGEVEC_SIZE 14
		/* 15 pointers + header align the pagevec structure to a power of two */
		#define PAGEVEC_SIZE 15

		struct page;
		struct address_space;

		struct pagevec {
		unsigned long nr;
		unsigned char nr;
		bool percpu_pvec_drained;
		struct page *pages[PAGEVEC_SIZE];
		};

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