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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2009-04-02 16:57:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-02 19:04:56 -0700
commita3b2d692690aef228e493b1beaafe5364cab3237 (patch)
treed3ad99c5370462861a1b918b4136e7bd7ad78e52 /include/linux/page_cgroup.h
parent3c776e64660028236313f0e54f3a9945764422df (diff)
cgroups: use css id in swap cgroup for saving memory v5
Try to use CSS ID for records in swap_cgroup. By this, on 64bit machine, size of swap_cgroup goes down to 2 bytes from 8bytes. This means, when 2GB of swap is equipped, (assume the page size is 4096bytes) From size of swap_cgroup = 2G/4k * 8 = 4Mbytes. To size of swap_cgroup = 2G/4k * 2 = 1Mbytes. Reduction is large. Of course, there are trade-offs. This CSS ID will add overhead to swap-in/swap-out/swap-free. But in general, - swap is a resource which the user tend to avoid use. - If swap is never used, swap_cgroup area is not used. - Reading traditional manuals, size of swap should be proportional to size of memory. Memory size of machine is increasing now. I think reducing size of swap_cgroup makes sense. Note: - ID->CSS lookup routine has no locks, it's under RCU-Read-Side. - memcg can be obsolete at rmdir() but not freed while refcnt from swap_cgroup is available. Changelog v4->v5: - reworked on to memcg-charge-swapcache-to-proper-memcg.patch Changlog ->v4: - fixed not configured case. - deleted unnecessary comments. - fixed NULL pointer bug. - fixed message in dmesg. [nishimura@mxp.nes.nec.co.jp: css_tryget can be called twice in !PageCgroupUsed case] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/page_cgroup.h')
-rw-r--r--include/linux/page_cgroup.h13
1 files changed, 6 insertions, 7 deletions
diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 602cc1fdee90..7339c7bf7331 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -91,24 +91,23 @@ static inline void page_cgroup_init(void)
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
#include <linux/swap.h>
-extern struct mem_cgroup *
-swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem);
-extern struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent);
+extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id);
+extern unsigned short lookup_swap_cgroup(swp_entry_t ent);
extern int swap_cgroup_swapon(int type, unsigned long max_pages);
extern void swap_cgroup_swapoff(int type);
#else
#include <linux/swap.h>
static inline
-struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem)
+unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
{
- return NULL;
+ return 0;
}
static inline
-struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent)
+unsigned short lookup_swap_cgroup(swp_entry_t ent)
{
- return NULL;
+ return 0;
}
static inline int