1306a85aed
Memory cgroups used to have 5 per-page pointers. To allow users to
disable that amount of overhead during runtime, those pointers were
allocated in a separate array, with a translation layer between them and
struct page.
There is now only one page pointer remaining: the memcg pointer, that
indicates which cgroup the page is associated with when charged. The
complexity of runtime allocation and the runtime translation overhead is
no longer justified to save that *potential* 0.19% of memory. With
CONFIG_SLUB, page->mem_cgroup actually sits in the doubleword padding
after the page->private member and doesn't even increase struct page,
and then this patch actually saves space. Remaining users that care can
still compile their kernels without CONFIG_MEMCG.
text data bss dec hex filename
8828345 1725264 983040 11536649 b00909 vmlinux.old
8827425 1725264 966656 11519345 afc571 vmlinux.new
[mhocko@suse.cz: update Documentation/cgroups/memory.txt]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
41 lines
874 B
C
41 lines
874 B
C
#ifndef __LINUX_PAGE_CGROUP_H
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#define __LINUX_PAGE_CGROUP_H
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#include <linux/swap.h>
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#ifdef CONFIG_MEMCG_SWAP
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extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
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unsigned short old, unsigned short new);
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extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id);
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extern unsigned short lookup_swap_cgroup_id(swp_entry_t ent);
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extern int swap_cgroup_swapon(int type, unsigned long max_pages);
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extern void swap_cgroup_swapoff(int type);
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#else
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static inline
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unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
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{
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return 0;
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}
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static inline
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unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
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{
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return 0;
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}
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static inline int
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swap_cgroup_swapon(int type, unsigned long max_pages)
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{
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return 0;
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}
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static inline void swap_cgroup_swapoff(int type)
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{
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return;
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}
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#endif /* CONFIG_MEMCG_SWAP */
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#endif /* __LINUX_PAGE_CGROUP_H */
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