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memcg: remove direct page_cgroup-to-page pointer

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In struct page_cgroup, we have a full word for flags but only a few are
reserved.  Use the remaining upper bits to encode, depending on
configuration, the node or the section, to enable page_cgroup-to-page
lookups without a direct pointer.

This saves a full word for every page in a system with memory cgroups
enabled.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner
2011-03-23 16:42:30 -07:00
committed by Linus Torvalds
parent 5564e88ba6
commit 6b3ae58efc
4 changed files with 117 additions and 55 deletions
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75
include/linux/page_cgroup.h
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@@ -1,8 +1,26 @@
#ifndef __LINUX_PAGE_CGROUP_H
#define __LINUX_PAGE_CGROUP_H
enum {
/* flags for mem_cgroup */
PCG_LOCK, /* Lock for pc->mem_cgroup and following bits. */
PCG_CACHE, /* charged as cache */
PCG_USED, /* this object is in use. */
PCG_MIGRATION, /* under page migration */
/* flags for mem_cgroup and file and I/O status */
PCG_MOVE_LOCK, /* For race between move_account v.s. following bits */
PCG_FILE_MAPPED, /* page is accounted as "mapped" */
/* No lock in page_cgroup */
PCG_ACCT_LRU, /* page has been accounted for (under lru_lock) */
__NR_PCG_FLAGS,
};
#ifndef __GENERATING_BOUNDS_H
#include <generated/bounds.h>
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
#include <linux/bit_spinlock.h>
/*
* Page Cgroup can be considered as an extended mem_map.
* A page_cgroup page is associated with every page descriptor. The
@@ -13,7 +31,6 @@
struct page_cgroup {
unsigned long flags;
struct mem_cgroup *mem_cgroup;
struct page *page;
struct list_head lru; /* per cgroup LRU list */
};
@@ -32,19 +49,7 @@ static inline void __init page_cgroup_init(void)
#endif
struct page_cgroup *lookup_page_cgroup(struct page *page);
enum {
/* flags for mem_cgroup */
PCG_LOCK, /* Lock for pc->mem_cgroup and following bits. */
PCG_CACHE, /* charged as cache */
PCG_USED, /* this object is in use. */
PCG_MIGRATION, /* under page migration */
/* flags for mem_cgroup and file and I/O status */
PCG_MOVE_LOCK, /* For race between move_account v.s. following bits */
PCG_FILE_MAPPED, /* page is accounted as "mapped" */
/* No lock in page_cgroup */
PCG_ACCT_LRU, /* page has been accounted for (under lru_lock) */
};
struct page *lookup_cgroup_page(struct page_cgroup *pc);
#define TESTPCGFLAG(uname, lname) \
static inline int PageCgroup##uname(struct page_cgroup *pc) \
@@ -117,6 +122,39 @@ static inline void move_unlock_page_cgroup(struct page_cgroup *pc,
local_irq_restore(*flags);
}
#ifdef CONFIG_SPARSEMEM
#define PCG_ARRAYID_WIDTH SECTIONS_SHIFT
#else
#define PCG_ARRAYID_WIDTH NODES_SHIFT
#endif
#if (PCG_ARRAYID_WIDTH > BITS_PER_LONG - NR_PCG_FLAGS)
#error Not enough space left in pc->flags to store page_cgroup array IDs
#endif
/* pc->flags: ARRAY-ID | FLAGS */
#define PCG_ARRAYID_MASK ((1UL << PCG_ARRAYID_WIDTH) - 1)
#define PCG_ARRAYID_OFFSET (BITS_PER_LONG - PCG_ARRAYID_WIDTH)
/*
* Zero the shift count for non-existant fields, to prevent compiler
* warnings and ensure references are optimized away.
*/
#define PCG_ARRAYID_SHIFT (PCG_ARRAYID_OFFSET * (PCG_ARRAYID_WIDTH != 0))
static inline void set_page_cgroup_array_id(struct page_cgroup *pc,
unsigned long id)
{
pc->flags &= ~(PCG_ARRAYID_MASK << PCG_ARRAYID_SHIFT);
pc->flags |= (id & PCG_ARRAYID_MASK) << PCG_ARRAYID_SHIFT;
}
static inline unsigned long page_cgroup_array_id(struct page_cgroup *pc)
{
return (pc->flags >> PCG_ARRAYID_SHIFT) & PCG_ARRAYID_MASK;
}
#else /* CONFIG_CGROUP_MEM_RES_CTLR */
struct page_cgroup;
@@ -137,7 +175,7 @@ static inline void __init page_cgroup_init_flatmem(void)
{
}
#endif
#endif /* CONFIG_CGROUP_MEM_RES_CTLR */
#include <linux/swap.h>
@@ -173,5 +211,8 @@ static inline void swap_cgroup_swapoff(int type)
return;
}
#endif
#endif
#endif /* CONFIG_CGROUP_MEM_RES_CTLR_SWAP */
#endif /* !__GENERATING_BOUNDS_H */
#endif /* __LINUX_PAGE_CGROUP_H */