From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 12A496B0055 for ; Fri, 5 Jun 2009 01:53:15 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n555rDSF018159 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 5 Jun 2009 14:53:13 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id CFFAB45DE7B for ; Fri, 5 Jun 2009 14:53:12 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 8B19D45DE6E for ; Fri, 5 Jun 2009 14:53:12 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 6B6B9E08008 for ; Fri, 5 Jun 2009 14:53:12 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 106961DB8040 for ; Fri, 5 Jun 2009 14:53:12 +0900 (JST) Date: Fri, 5 Jun 2009 14:51:41 +0900 From: KAMEZAWA Hiroyuki Subject: Re: Low overhead patches for the memory cgroup controller (v3) Message-Id: <20090605145141.c9d0f4cf.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090605053107.GF11755@balbir.in.ibm.com> References: <20090515181639.GH4451@balbir.in.ibm.com> <20090518191107.8a7cc990.kamezawa.hiroyu@jp.fujitsu.com> <20090531235121.GA6120@balbir.in.ibm.com> <20090602085744.2eebf211.kamezawa.hiroyu@jp.fujitsu.com> <20090605053107.GF11755@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: Andrew Morton , "linux-mm@kvack.org" , "nishimura@mxp.nes.nec.co.jp" , "lizf@cn.fujitsu.com" , "menage@google.com" , KOSAKI Motohiro List-ID: On Fri, 5 Jun 2009 13:31:07 +0800 Balbir Singh wrote: > Here is the new version of the patch with the RFC dropped. Andrew, > Kame, could you please take a look. I am just about to fly out to get > back home tomorrow, so there might be some silence, unless I get to > the next WiFi enabled airport. > > > From: Balbir Singh > > Changelog v3 -> v2 > > 1. Rebase to mmotm 2nd June 2009 > 2. Test with some of the test cases recommended by Daisuke-San > > Changelog v2 -> v1 > 1. Fix and implement review comments. > > Feature: Remove the overhead associated with the root cgroup > > 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. A new flag to track whether the page has been accounted or not > has been added as well. Flags are now set atomically for page_cgroup, > pcg_default_flags is now obsolete, but I've not removed it yet. It > provides some readability to help the code. > > Tests Results: > > Obtained by > > 1. Using tmpfs for mounting filesystem > 2. Changing sync to be /bin/true (so that sync is not the bottleneck) > 3. Used -s #cpus*40 -e #cpus*40 > > Reaim > withoutpatch patch > AIM9 9532.48 9807.59 > dbase 19344.60 19285.71 > new_dbase 20101.65 20163.13 > shared 11827.77 11886.65 > compute 17317.38 17420.05 > A few comments. > Signed-off-by: Balbir Singh > --- > > include/linux/page_cgroup.h | 12 ++++++++++++ > mm/memcontrol.c | 42 ++++++++++++++++++++++++++++++++++++++---- > mm/page_cgroup.c | 1 - > 3 files changed, 50 insertions(+), 5 deletions(-) > > > diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h > index 7339c7b..41cc16c 100644 > --- a/include/linux/page_cgroup.h > +++ b/include/linux/page_cgroup.h > @@ -26,6 +26,8 @@ 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 */ > + PCG_ACCT_LRU, /* page has been accounted for */ > }; > > #define TESTPCGFLAG(uname, lname) \ > @@ -42,9 +44,19 @@ static inline void ClearPageCgroup##uname(struct page_cgroup *pc) \ > > /* Cache flag is set only once (at allocation) */ > TESTPCGFLAG(Cache, CACHE) > +SETPCGFLAG(Cache, CACHE) > > TESTPCGFLAG(Used, USED) > CLEARPCGFLAG(Used, USED) > +SETPCGFLAG(Used, USED) > + > +SETPCGFLAG(Root, ROOT) > +CLEARPCGFLAG(Root, ROOT) > +TESTPCGFLAG(Root, ROOT) > + > +SETPCGFLAG(AcctLru, ACCT_LRU) > +CLEARPCGFLAG(AcctLru, ACCT_LRU) > +TESTPCGFLAG(AcctLru, ACCT_LRU) > I prefer AcctLRU rather than AcctLru. LRU is LRU or lru and not Lru through the kernel. > static inline int page_cgroup_nid(struct page_cgroup *pc) > { > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index a83e039..9561d10 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 = 1 */ > @@ -197,6 +198,10 @@ enum charge_type { > #define PCGF_CACHE (1UL << PCG_CACHE) > #define PCGF_USED (1UL << PCG_USED) > #define PCGF_LOCK (1UL << PCG_LOCK) > +/* Not used, but added here for completeness */ > +#define PCGF_ROOT (1UL << PCG_ROOT) > +#define PCGF_ACCT (1UL << PCG_ACCT) > + > static const unsigned long > pcg_default_flags[NR_CHARGE_TYPE] = { > PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* File Cache */ Could you delete this default_flags ? This is of no use after this patch. > @@ -375,7 +380,7 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru) > return; > pc = lookup_page_cgroup(page); > /* can happen while we handle swapcache. */ > - if (list_empty(&pc->lru) || !pc->mem_cgroup) > + if ((!PageCgroupAcctLru(pc) && list_empty(&pc->lru)) || !pc->mem_cgroup) > return; I wonder this condition is valid one or not.. IMHO, all check here should be == if (!PageCgroupAcctLru(pc) || !pc->mem_cgroup) return; mz = page_cgroup_zoneinfo(pc); mem = pc->mem_cgroup; MEM_CGROUP_ZSTAT(mz, lru) -= 1; ClearPageCgroupAcctLru(pc); if (PageCgroupRoot(pc)) return; VM_BUGON(list_empty(&pc->lru); list_del_init(&pc->lru); return; == I'm sorry if there is a case (PageCgroupAcctLru(pc) && !PageCgroupRoot(pc) && list_empty(&pc->lru)) > /* > * We don't check PCG_USED bit. It's cleared when the "page" is finally > @@ -384,6 +389,9 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru) > mz = page_cgroup_zoneinfo(pc); > mem = pc->mem_cgroup; > MEM_CGROUP_ZSTAT(mz, lru) -= 1; > + ClearPageCgroupAcctLru(pc); > + if (PageCgroupRoot(pc)) > + return; > list_del_init(&pc->lru); > return; > } > @@ -407,8 +415,8 @@ 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]); > @@ -432,6 +440,9 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru) > > mz = page_cgroup_zoneinfo(pc); > MEM_CGROUP_ZSTAT(mz, lru) += 1; > + SetPageCgroupAcctLru(pc); > + if (PageCgroupRoot(pc)) > + return; > list_add(&pc->lru, &mz->lists[lru]); > } > > @@ -1107,9 +1118,24 @@ 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]; > + switch (ctype) { > + case MEM_CGROUP_CHARGE_TYPE_CACHE: > + case MEM_CGROUP_CHARGE_TYPE_SHMEM: > + SetPageCgroupCache(pc); > + SetPageCgroupUsed(pc); > + break; > + case MEM_CGROUP_CHARGE_TYPE_MAPPED: > + SetPageCgroupUsed(pc); > + break; > + default: > + break; > + } > + > + if (mem == root_mem_cgroup) > + SetPageCgroupRoot(pc); > > mem_cgroup_charge_statistics(mem, pc, true); > My concern here is there will be a racy moment that pc->flag shows PageCgroupUsed(pc) && !PageCgroupRoot(pc) even if pc->mem_cgroup == root_mem_cgroup. Then, The order of code here should be == if (mem == root_mem_cgroup) SetPageCgroupRoot(pc); pc->mem_cgroup == mem;; smp_wmb(); switch(type) { case.... } // Used bit is set at last. == But I wonder it's better to use == static inline int page_cgroup_is_under_root(pc) { pc->mem_cgroup == root_mem_cgroup; } == I'm not sure why PageCgroupRoot() "bit" is necessary. Could you clarify the benefit of Root flag ? > @@ -1515,6 +1541,8 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) > mem_cgroup_charge_statistics(mem, pc, false); > > ClearPageCgroupUsed(pc); > + if (mem == root_mem_cgroup) > + ClearPageCgroupRoot(pc); > /* > * pc->mem_cgroup is not cleared here. It will be accessed when it's > * freed from LRU. This is safe because uncharged page is expected not > @@ -2036,6 +2064,10 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft, > name = MEMFILE_ATTR(cft->private); > switch (name) { > case RES_LIMIT: > + if (memcg == root_mem_cgroup) { /* Can't set limit on root */ > + ret = -EINVAL; > + break; > + } > /* This function does all necessary parse...reuse it */ > ret = res_counter_memparse_write_strategy(buffer, &val); > if (ret) > @@ -2502,6 +2534,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont) > if (cont->parent == NULL) { > enable_swap_cgroup(); > parent = NULL; > + root_mem_cgroup = mem; > } else { > parent = mem_cgroup_from_cont(cont->parent); > mem->use_hierarchy = parent->use_hierarchy; > @@ -2530,6 +2563,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont) > return &mem->css; > free_out: > __mem_cgroup_free(mem); > + root_mem_cgroup = NULL; > return ERR_PTR(error); > } > > diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c > index ecc3918..4406a9c 100644 > --- a/mm/page_cgroup.c > +++ b/mm/page_cgroup.c > @@ -276,7 +276,6 @@ void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat) > > #endif > > - > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP > > static DEFINE_MUTEX(swap_cgroup_mutex); > Unnecessary diff here. Thanks, -Kame -- 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