From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id BC3976B0168 for ; Wed, 13 May 2009 22:57:08 -0400 (EDT) Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e9.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id n4E2kYhB002753 for ; Wed, 13 May 2009 22:46:34 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n4E2w06j190158 for ; Wed, 13 May 2009 22:58:00 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n4E2u2LO030694 for ; Wed, 13 May 2009 22:56:02 -0400 Date: Thu, 14 May 2009 08:12:50 +0530 From: Balbir Singh Subject: Re: [RFC] Low overhead patches for the memory resource controller Message-ID: <20090514024250.GU13394@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090513153218.GQ13394@balbir.in.ibm.com> <20090514094223.6c23e469.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090514094223.6c23e469.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , Andrew Morton , "nishimura@mxp.nes.nec.co.jp" , "lizf@cn.fujitsu.com" , KOSAKI Motohiro List-ID: * KAMEZAWA Hiroyuki [2009-05-14 09:42:23]: > On Wed, 13 May 2009 21:02:18 +0530 > Balbir Singh wrote: > > > Important: Not for inclusion, for discussion only > > > > I've been experimenting with a version of the patches below. They add > > a PCGF_ROOT flag for tracking pages belonging to the root cgroup and > > disable LRU manipulation for them > > > > Caveats: > > > > 1. I've not checked accounting, accounting might be broken > > 2. I've not made the root cgroup as non limitable, we need to disable > > hard limits once we agree to go with this > > > > > > Tests > > > > Quick tests show an improvement with AIM9 > > > > mmotm+patch mmtom-08-may-2009 > > AIM9 1338.57 1338.17 > > Dbase 18034.16 16021.58 > > New Dbase 18482.24 16518.54 > > Shared 9935.98 8882.11 > > Compute 16619.81 15226.13 > > > > Comments on the approach much appreciated > > > > Feature: Remove the overhead associated with the root cgroup > > > > From: Balbir Singh > > > > This patch changes the memory cgroup and removes the overhead associated > > with accounting all pages in the root cgroup. As a side-effect, we can > > no longer set a memory hard limit in the root cgroup. > > > > A new flag is used to track page_cgroup associated with the root cgroup > > pages. > > --- > > > > include/linux/page_cgroup.h | 5 +++++ > > mm/memcontrol.c | 23 +++++++++++++++++------ > > mm/page_cgroup.c | 1 - > > 3 files changed, 22 insertions(+), 7 deletions(-) > > > > > > diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h > > index 7339c7b..9c88e85 100644 > > --- a/include/linux/page_cgroup.h > > +++ b/include/linux/page_cgroup.h > > @@ -26,6 +26,7 @@ enum { > > PCG_LOCK, /* page cgroup is locked */ > > PCG_CACHE, /* charged as cache */ > > PCG_USED, /* this object is in use. */ > > + PCG_ROOT, /* page belongs to root cgroup */ > > }; > > > > #define TESTPCGFLAG(uname, lname) \ > > @@ -46,6 +47,10 @@ TESTPCGFLAG(Cache, CACHE) > > TESTPCGFLAG(Used, USED) > > CLEARPCGFLAG(Used, USED) > > > > +SETPCGFLAG(Root, ROOT) > > +CLEARPCGFLAG(Root, ROOT) > > +TESTPCGFLAG(Root, ROOT) > > + > > static inline int page_cgroup_nid(struct page_cgroup *pc) > > { > > return page_to_nid(pc->page); > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 9712ef7..2750bed 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -43,6 +43,7 @@ > > > > struct cgroup_subsys mem_cgroup_subsys __read_mostly; > > #define MEM_CGROUP_RECLAIM_RETRIES 5 > > +struct mem_cgroup *root_mem_cgroup __read_mostly; > > > > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP > > /* Turned on only when memory cgroup is enabled && really_do_swap_account = 0 */ > > @@ -196,6 +197,7 @@ enum charge_type { > > #define PCGF_CACHE (1UL << PCG_CACHE) > > #define PCGF_USED (1UL << PCG_USED) > > #define PCGF_LOCK (1UL << PCG_LOCK) > > +#define PCGF_ROOT (1UL << PCG_ROOT) > > static const unsigned long > > pcg_default_flags[NR_CHARGE_TYPE] = { > > PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* File Cache */ > > @@ -422,6 +424,8 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru) > > /* can happen while we handle swapcache. */ > > if (list_empty(&pc->lru) || !pc->mem_cgroup) > > return; > > + if (PageCgroupRoot(pc)) > > + return; > > /* > > * We don't check PCG_USED bit. It's cleared when the "page" is finally > > * removed from global LRU. > > @@ -452,8 +456,8 @@ void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru) > > * For making pc->mem_cgroup visible, insert smp_rmb() here. > > */ > > smp_rmb(); > > - /* unused page is not rotated. */ > > - if (!PageCgroupUsed(pc)) > > + /* unused or root page is not rotated. */ > > + if (!PageCgroupUsed(pc) || PageCgroupRoot(pc)) > > return; > > mz = page_cgroup_zoneinfo(pc); > > list_move(&pc->lru, &mz->lists[lru]); > > @@ -472,7 +476,7 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru) > > * For making pc->mem_cgroup visible, insert smp_rmb() here. > > */ > > smp_rmb(); > > - if (!PageCgroupUsed(pc)) > > + if (!PageCgroupUsed(pc) || PageCgroupRoot(pc)) > > return; > > > > mz = page_cgroup_zoneinfo(pc); > > @@ -1114,9 +1118,12 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem, > > css_put(&mem->css); > > return; > > } > > - pc->mem_cgroup = mem; > > - smp_wmb(); > > - pc->flags = pcg_default_flags[ctype]; > > + if (mem != root_mem_cgroup) { > > + pc->mem_cgroup = mem; > > + smp_wmb(); > > + pc->flags = pcg_default_flags[ctype]; > > + } else > > + SetPageCgroupRoot(pc); > > > This means > PCG_USED is not set. (then uncharge_common will be skipped completely.) > LOCK bit is dropped here. > > After fix, the test result will change. > Yep, I've not checked the impact on accounting. I think I need a check to see for !Used && Root to make sure the accounting is not broken. I'll test again. -- Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org