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Release 4.12 include/linux/page-flags-layout.h

Directory: include/linux
#ifndef PAGE_FLAGS_LAYOUT_H

#define PAGE_FLAGS_LAYOUT_H

#include <linux/numa.h>
#include <generated/bounds.h>

/*
 * When a memory allocation must conform to specific limitations (such
 * as being suitable for DMA) the caller will pass in hints to the
 * allocator in the gfp_mask, in the zone modifier bits.  These bits
 * are used to select a priority ordered list of memory zones which
 * match the requested limits. See gfp_zone() in include/linux/gfp.h
 */
#if MAX_NR_ZONES < 2

#define ZONES_SHIFT 0
#elif MAX_NR_ZONES <= 2

#define ZONES_SHIFT 1
#elif MAX_NR_ZONES <= 4

#define ZONES_SHIFT 2
#elif MAX_NR_ZONES <= 8

#define ZONES_SHIFT 3
#else
#error ZONES_SHIFT -- too many zones configured adjust calculation
#endif

#ifdef CONFIG_SPARSEMEM
#include <asm/sparsemem.h>

/* SECTION_SHIFT        #bits space required to store a section # */

#define SECTIONS_SHIFT	(MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

#endif /* CONFIG_SPARSEMEM */

/*
 * page->flags layout:
 *
 * There are five possibilities for how page->flags get laid out.  The first
 * pair is for the normal case without sparsemem. The second pair is for
 * sparsemem when there is plenty of space for node and section information.
 * The last is when there is insufficient space in page->flags and a separate
 * lookup is necessary.
 *
 * No sparsemem or sparsemem vmemmap: |       NODE     | ZONE |             ... | FLAGS |
 *      " plus space for last_cpupid: |       NODE     | ZONE | LAST_CPUPID ... | FLAGS |
 * classic sparse with space for node:| SECTION | NODE | ZONE |             ... | FLAGS |
 *      " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS |
 * classic sparse no space for node:  | SECTION |     ZONE    | ... | FLAGS |
 */
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)

#define SECTIONS_WIDTH		SECTIONS_SHIFT
#else

#define SECTIONS_WIDTH		0
#endif


#define ZONES_WIDTH		ZONES_SHIFT

#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS

#define NODES_WIDTH		NODES_SHIFT
#else
#ifdef CONFIG_SPARSEMEM_VMEMMAP
#error "Vmemmap: No space for nodes field in page flags"
#endif

#define NODES_WIDTH		0
#endif

#ifdef CONFIG_NUMA_BALANCING

#define LAST__PID_SHIFT 8

#define LAST__PID_MASK  ((1 << LAST__PID_SHIFT)-1)


#define LAST__CPU_SHIFT NR_CPUS_BITS

#define LAST__CPU_MASK  ((1 << LAST__CPU_SHIFT)-1)


#define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT)
#else

#define LAST_CPUPID_SHIFT 0
#endif

#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS

#define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
#else

#define LAST_CPUPID_WIDTH 0
#endif

/*
 * We are going to use the flags for the page to node mapping if its in
 * there.  This includes the case where there is no node, so it is implicit.
 */
#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)

#define NODE_NOT_IN_PAGE_FLAGS
#endif

#if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0

#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
#endif

#endif /* _LINUX_PAGE_FLAGS_LAYOUT */

Overall Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra20190.54%360.00%
Mel Gorman125.41%120.00%
Dan J Williams94.05%120.00%
Total222100.00%5100.00%
Directory: include/linux
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