Commit 5bfec9f6 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] Save some memory in mem_map on x86-64

From: Andi Kleen <ak@suse.de>

This patch saves 2MB of memory on a 1GB x86-64 machine, 20MB on a 10GB
machine.  It does this by eliminating 8 bytes of useless padding in struct
page.

This resurrects an older patch in a hopefully cleaner form.
parent 952a0ae3
...@@ -503,6 +503,8 @@ static __inline__ int ffs(int x) ...@@ -503,6 +503,8 @@ static __inline__ int ffs(int x)
/* find last set bit */ /* find last set bit */
#define fls(x) generic_fls(x) #define fls(x) generic_fls(x)
#define ARCH_HAS_ATOMIC_UNSIGNED 1
#endif /* __KERNEL__ */ #endif /* __KERNEL__ */
#endif /* _X86_64_BITOPS_H */ #endif /* _X86_64_BITOPS_H */
...@@ -152,6 +152,12 @@ struct pte_chain; ...@@ -152,6 +152,12 @@ struct pte_chain;
struct mmu_gather; struct mmu_gather;
struct inode; struct inode;
#ifdef ARCH_HAS_ATOMIC_UNSIGNED
typedef unsigned page_flags_t;
#else
typedef unsigned long page_flags_t;
#endif
/* /*
* Each physical page in the system has a struct page associated with * Each physical page in the system has a struct page associated with
* it to keep track of whatever it is we are using the page for at the * it to keep track of whatever it is we are using the page for at the
...@@ -168,7 +174,7 @@ struct inode; ...@@ -168,7 +174,7 @@ struct inode;
* TODO: make this structure smaller, it could be as small as 32 bytes. * TODO: make this structure smaller, it could be as small as 32 bytes.
*/ */
struct page { struct page {
unsigned long flags; /* atomic flags, some possibly page_flags_t flags; /* atomic flags, some possibly
updated asynchronously */ updated asynchronously */
atomic_t count; /* Usage count, see below. */ atomic_t count; /* Usage count, see below. */
struct list_head list; /* ->mapping has some page lists. */ struct list_head list; /* ->mapping has some page lists. */
...@@ -333,7 +339,7 @@ static inline void put_page(struct page *page) ...@@ -333,7 +339,7 @@ static inline void put_page(struct page *page)
* We'll have up to (MAX_NUMNODES * MAX_NR_ZONES) zones total, * We'll have up to (MAX_NUMNODES * MAX_NR_ZONES) zones total,
* so we use (MAX_NODES_SHIFT + MAX_ZONES_SHIFT) here to get enough bits. * so we use (MAX_NODES_SHIFT + MAX_ZONES_SHIFT) here to get enough bits.
*/ */
#define NODEZONE_SHIFT (BITS_PER_LONG - MAX_NODES_SHIFT - MAX_ZONES_SHIFT) #define NODEZONE_SHIFT (sizeof(page_flags_t)*8 - MAX_NODES_SHIFT - MAX_ZONES_SHIFT)
#define NODEZONE(node, zone) ((node << ZONES_SHIFT) | zone) #define NODEZONE(node, zone) ((node << ZONES_SHIFT) | zone)
static inline unsigned long page_zonenum(struct page *page) static inline unsigned long page_zonenum(struct page *page)
......
...@@ -316,7 +316,7 @@ extern struct pglist_data contig_page_data; ...@@ -316,7 +316,7 @@ extern struct pglist_data contig_page_data;
#include <asm/mmzone.h> #include <asm/mmzone.h>
#if BITS_PER_LONG == 32 #if BITS_PER_LONG == 32 || defined(ARCH_HAS_ATOMIC_UNSIGNED)
/* /*
* with 32 bit page->flags field, we reserve 8 bits for node/zone info. * with 32 bit page->flags field, we reserve 8 bits for node/zone info.
* there are 3 zones (2 bits) and this leaves 8-2=6 bits for nodes. * there are 3 zones (2 bits) and this leaves 8-2=6 bits for nodes.
......
...@@ -10,8 +10,8 @@ ...@@ -10,8 +10,8 @@
struct pte_chain; struct pte_chain;
extern kmem_cache_t *pte_chain_cache; extern kmem_cache_t *pte_chain_cache;
#define pte_chain_lock(page) bit_spin_lock(PG_chainlock, &page->flags) #define pte_chain_lock(page) bit_spin_lock(PG_chainlock, (unsigned long *)&page->flags)
#define pte_chain_unlock(page) bit_spin_unlock(PG_chainlock, &page->flags) #define pte_chain_unlock(page) bit_spin_unlock(PG_chainlock, (unsigned long *)&page->flags)
struct pte_chain *pte_chain_alloc(int gfp_flags); struct pte_chain *pte_chain_alloc(int gfp_flags);
void __pte_chain_free(struct pte_chain *pte_chain); void __pte_chain_free(struct pte_chain *pte_chain);
......
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