[PATCH 2/13] Add a bitmap that is used to track flags affecting a block of pages
From: Mel Gorman
Date: Mon Sep 10 2007 - 07:21:16 EST
Subject: Add a bitmap that is used to track flags affecting a block of pages
The grouping pages by mobility patchset needs to track if pages within a block
can be moved or reclaimed so that pages are freed to the appropriate list.
This patch adds a bitmap for flags affecting a whole a pageblock_nr_pages
block of pages.
In non-SPARSEMEM configurations, the bitmap is stored in the struct zone
and allocated during initialisation. SPARSEMEM dynamically allocates the
bitmap in a struct mem_section as required.
Additional credit to Andy Whitcroft who reviewed up an earlier implementation
of the mechanism an suggested how to make it a *lot* cleaner.
Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
Cc: Andy Whitcroft <apw@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 13 +++
include/linux/pageblock-flags.h | 74 ++++++++++++++++++
mm/page_alloc.c | 137 +++++++++++++++++++++++++++++++++++
3 files changed, 224 insertions(+)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc5-001-ia64-parse-kernel-parameter-hugepagesz=-in-early-boot/include/linux/mmzone.h linux-2.6.23-rc5-002-add-a-bitmap-that-is-used-to-track-flags-affecting-a-block-of-pages/include/linux/mmzone.h
--- linux-2.6.23-rc5-001-ia64-parse-kernel-parameter-hugepagesz=-in-early-boot/include/linux/mmzone.h 2007-09-02 16:18:27.000000000 +0100
+++ linux-2.6.23-rc5-002-add-a-bitmap-that-is-used-to-track-flags-affecting-a-block-of-pages/include/linux/mmzone.h 2007-09-02 16:19:05.000000000 +0100
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/seqlock.h>
#include <linux/nodemask.h>
+#include <linux/pageblock-flags.h>
#include <asm/atomic.h>
#include <asm/page.h>
@@ -222,6 +223,14 @@ struct zone {
#endif
struct free_area free_area[MAX_ORDER];
+#ifndef CONFIG_SPARSEMEM
+ /*
+ * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
+ * In SPARSEMEM, this map is stored in struct mem_section
+ */
+ unsigned long *pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+
ZONE_PADDING(_pad1_)
@@ -708,6 +717,9 @@ extern struct zone *next_zone(struct zon
#define PAGES_PER_SECTION (1UL << PFN_SECTION_SHIFT)
#define PAGE_SECTION_MASK (~(PAGES_PER_SECTION-1))
+#define SECTION_BLOCKFLAGS_BITS \
+ ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
+
#if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
#error Allocator MAX_ORDER exceeds SECTION_SIZE
#endif
@@ -727,6 +739,7 @@ struct mem_section {
* before using it wrong.
*/
unsigned long section_mem_map;
+ DECLARE_BITMAP(pageblock_flags, SECTION_BLOCKFLAGS_BITS);
};
#ifdef CONFIG_SPARSEMEM_EXTREME
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc5-001-ia64-parse-kernel-parameter-hugepagesz=-in-early-boot/include/linux/pageblock-flags.h linux-2.6.23-rc5-002-add-a-bitmap-that-is-used-to-track-flags-affecting-a-block-of-pages/include/linux/pageblock-flags.h
--- linux-2.6.23-rc5-001-ia64-parse-kernel-parameter-hugepagesz=-in-early-boot/include/linux/pageblock-flags.h 2007-09-02 16:18:27.000000000 +0100
+++ linux-2.6.23-rc5-002-add-a-bitmap-that-is-used-to-track-flags-affecting-a-block-of-pages/include/linux/pageblock-flags.h 2007-09-02 16:19:05.000000000 +0100
@@ -0,0 +1,74 @@
+/*
+ * Macros for manipulating and testing flags related to a
+ * pageblock_nr_pages number of pages.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2006
+ *
+ * Original author, Mel Gorman
+ * Major cleanups and reduction of bit operations, Andy Whitcroft
+ */
+#ifndef PAGEBLOCK_FLAGS_H
+#define PAGEBLOCK_FLAGS_H
+
+#include <linux/types.h>
+
+/* Macro to aid the definition of ranges of bits */
+#define PB_range(name, required_bits) \
+ name, name ## _end = (name + required_bits) - 1
+
+/* Bit indices that affect a whole block of pages */
+enum pageblock_bits {
+ NR_PAGEBLOCK_BITS
+};
+
+#ifdef CONFIG_HUGETLB_PAGE
+
+#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+
+/* Huge page sizes are variable */
+extern int pageblock_order;
+
+#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+
+/* Huge pages are a constant size */
+#define pageblock_order HUGETLB_PAGE_ORDER
+
+#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+
+#else /* CONFIG_HUGETLB_PAGE */
+
+/* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
+#define pageblock_order (MAX_ORDER-1)
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+#define pageblock_nr_pages (1UL << pageblock_order)
+
+/* Forward declaration */
+struct page;
+
+/* Declarations for getting and setting flags. See mm/page_alloc.c */
+unsigned long get_pageblock_flags_group(struct page *page,
+ int start_bitidx, int end_bitidx);
+void set_pageblock_flags_group(struct page *page, unsigned long flags,
+ int start_bitidx, int end_bitidx);
+
+#define get_pageblock_flags(page) \
+ get_pageblock_flags_group(page, 0, NR_PAGEBLOCK_BITS-1)
+#define set_pageblock_flags(page) \
+ set_pageblock_flags_group(page, 0, NR_PAGEBLOCK_BITS-1)
+
+#endif /* PAGEBLOCK_FLAGS_H */
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc5-001-ia64-parse-kernel-parameter-hugepagesz=-in-early-boot/mm/page_alloc.c linux-2.6.23-rc5-002-add-a-bitmap-that-is-used-to-track-flags-affecting-a-block-of-pages/mm/page_alloc.c
--- linux-2.6.23-rc5-001-ia64-parse-kernel-parameter-hugepagesz=-in-early-boot/mm/page_alloc.c 2007-09-02 16:18:31.000000000 +0100
+++ linux-2.6.23-rc5-002-add-a-bitmap-that-is-used-to-track-flags-affecting-a-block-of-pages/mm/page_alloc.c 2007-09-02 16:19:05.000000000 +0100
@@ -59,6 +59,10 @@ unsigned long totalreserve_pages __read_
long nr_swap_pages;
int percpu_pagelist_fraction;
+#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+int pageblock_order __read_mostly;
+#endif
+
static void __free_pages_ok(struct page *page, unsigned int order);
/*
@@ -2901,6 +2905,62 @@ static void __meminit calculate_node_tot
realtotalpages);
}
+#ifndef CONFIG_SPARSEMEM
+/*
+ * Calculate the size of the zone->blockflags rounded to an unsigned long
+ * Start by making sure zonesize is a multiple of pageblock_order by rounding
+ * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
+ * round what is now in bits to nearest long in bits, then return it in
+ * bytes.
+ */
+static unsigned long __init usemap_size(unsigned long zonesize)
+{
+ unsigned long usemapsize;
+
+ usemapsize = roundup(zonesize, pageblock_nr_pages);
+ usemapsize = usemapsize >> pageblock_order;
+ usemapsize *= NR_PAGEBLOCK_BITS;
+ usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));
+
+ return usemapsize / 8;
+}
+
+static void __init setup_usemap(struct pglist_data *pgdat,
+ struct zone *zone, unsigned long zonesize)
+{
+ unsigned long usemapsize = usemap_size(zonesize);
+ zone->pageblock_flags = NULL;
+ if (usemapsize) {
+ zone->pageblock_flags = alloc_bootmem_node(pgdat, usemapsize);
+ memset(zone->pageblock_flags, 0, usemapsize);
+ }
+}
+#else
+static void inline setup_usemap(struct pglist_data *pgdat,
+ struct zone *zone, unsigned long zonesize) {}
+#endif /* CONFIG_SPARSEMEM */
+
+#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+/* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
+static inline void __init set_pageblock_order(unsigned int order)
+{
+ /* Check that pageblock_nr_pages has not already been setup */
+ if (pageblock_order)
+ return;
+
+ /*
+ * Assume the largest contiguous order of interest is a huge page.
+ * This value may be variable depending on boot parameters on IA64
+ */
+ pageblock_order = order;
+}
+#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+
+/* Defined this way to avoid accidently referencing HUGETLB_PAGE_ORDER */
+#define set_pageblock_order(x) do {} while (0)
+
+#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+
/*
* Set up the zone data structures:
* - mark all pages reserved
@@ -2981,6 +3041,8 @@ static void __meminit free_area_init_cor
if (!size)
continue;
+ set_pageblock_order(HUGETLB_PAGE_ORDER);
+ setup_usemap(pgdat, zone, size);
ret = init_currently_empty_zone(zone, zone_start_pfn,
size, MEMMAP_EARLY);
BUG_ON(ret);
@@ -3934,4 +3996,79 @@ EXPORT_SYMBOL(pfn_to_page);
EXPORT_SYMBOL(page_to_pfn);
#endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */
+/* Return a pointer to the bitmap storing bits affecting a block of pages */
+static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
+ unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+ return __pfn_to_section(pfn)->pageblock_flags;
+#else
+ return zone->pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+}
+static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+ pfn &= (PAGES_PER_SECTION-1);
+ return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+#else
+ pfn = pfn - zone->zone_start_pfn;
+ return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+/**
+ * get_pageblock_flags_group - Return the requested group of flags for the pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @start_bitidx: The first bit of interest to retrieve
+ * @end_bitidx: The last bit of interest
+ * returns pageblock_bits flags
+ */
+unsigned long get_pageblock_flags_group(struct page *page,
+ int start_bitidx, int end_bitidx)
+{
+ struct zone *zone;
+ unsigned long *bitmap;
+ unsigned long pfn, bitidx;
+ unsigned long flags = 0;
+ unsigned long value = 1;
+
+ zone = page_zone(page);
+ pfn = page_to_pfn(page);
+ bitmap = get_pageblock_bitmap(zone, pfn);
+ bitidx = pfn_to_bitidx(zone, pfn);
+
+ for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
+ if (test_bit(bitidx + start_bitidx, bitmap))
+ flags |= value;
+
+ return flags;
+}
+
+/**
+ * set_pageblock_flags_group - Set the requested group of flags for a pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @start_bitidx: The first bit of interest
+ * @end_bitidx: The last bit of interest
+ * @flags: The flags to set
+ */
+void set_pageblock_flags_group(struct page *page, unsigned long flags,
+ int start_bitidx, int end_bitidx)
+{
+ struct zone *zone;
+ unsigned long *bitmap;
+ unsigned long pfn, bitidx;
+ unsigned long value = 1;
+
+ zone = page_zone(page);
+ pfn = page_to_pfn(page);
+ bitmap = get_pageblock_bitmap(zone, pfn);
+ bitidx = pfn_to_bitidx(zone, pfn);
+
+ for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
+ if (flags & value)
+ __set_bit(bitidx + start_bitidx, bitmap);
+ else
+ __clear_bit(bitidx + start_bitidx, bitmap);
+}
-
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