From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id AAD966B004F for ; Thu, 17 Sep 2009 00:59:47 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n8H4xieZ018929 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 17 Sep 2009 13:59:44 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 35FF145DE61 for ; Thu, 17 Sep 2009 13:59:44 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id E8EDE45DE55 for ; Thu, 17 Sep 2009 13:59:43 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 807CC1DB803B for ; Thu, 17 Sep 2009 13:59:43 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id C47E6EF8003 for ; Thu, 17 Sep 2009 13:59:42 +0900 (JST) Date: Thu, 17 Sep 2009 13:57:37 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 5/8] memcg: migrate charge of anon Message-Id: <20090917135737.04c3b65f.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090917112656.908b44fa.nishimura@mxp.nes.nec.co.jp> References: <20090917112304.6cd4e6f6.nishimura@mxp.nes.nec.co.jp> <20090917112656.908b44fa.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Daisuke Nishimura Cc: linux-mm , Balbir Singh , Paul Menage , Li Zefan List-ID: On Thu, 17 Sep 2009 11:26:56 +0900 Daisuke Nishimura wrote: > This patch is the core part of this charge migration feature. > It adds functions to migrate charge of anonymous pages of the task. > > Implementation: > - define struct migrate_charge and a valuable of it(mc) to remember > the target pages and other information. > - At can_attach(), isolate the target pages, call __mem_cgroup_try_charge(), > and move them to mc->list. > - Call mem_cgroup_move_account() at attach() about all pages on mc->list > after necessary checks under page_cgroup lock, and put back them to LRU. > - Cancel charges about all pages remains on mc->list on failure or at the end > of charge migration, and put back them to LRU. > > > Signed-off-by: Daisuke Nishimura > --- > mm/memcontrol.c | 196 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 files changed, 195 insertions(+), 1 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index a6b07f8..3a3f4ac 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -21,6 +21,8 @@ > #include > #include > #include > +#include > +#include > #include > #include > #include > @@ -274,6 +276,18 @@ enum charge_type { > #define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2 > #define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT) > > +/* > + * Stuffs for migrating charge at task move. > + * mc and its members are protected by cgroup_lock > + */ > +struct migrate_charge { > + struct task_struct *tsk; > + struct mem_cgroup *from; > + struct mem_cgroup *to; > + struct list_head list; > +}; > +static struct migrate_charge *mc; > + > static void mem_cgroup_get(struct mem_cgroup *mem); > static void mem_cgroup_put(struct mem_cgroup *mem); > static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem); > @@ -2829,6 +2843,7 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft, > } > > enum migrate_charge_type { > + MIGRATE_CHARGE_ANON, > NR_MIGRATE_CHARGE_TYPE, > }; > > @@ -3184,10 +3199,164 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss, > return ret; > } > > +static int migrate_charge_prepare_pte_range(pmd_t *pmd, > + unsigned long addr, unsigned long end, > + struct mm_walk *walk) > +{ > + int ret = 0; > + struct page *page, *tmp; > + LIST_HEAD(list); > + struct vm_area_struct *vma = walk->private; > + pte_t *pte, ptent; > + spinlock_t *ptl; > + bool move_anon = (mc->to->migrate_charge & (1 << MIGRATE_CHARGE_ANON)); > + > + lru_add_drain_all(); plz call lru_add_drain_all() before taking mmap_sem(). This waits for workqueue in synchronous manner. (I think KOSAKI-san is working for better pagevec drain function.) > + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > + for (; addr != end; pte++, addr += PAGE_SIZE) { > + struct page_cgroup *pc; > + > + ptent = *pte; > + if (!pte_present(ptent)) > + continue; > + > + page = vm_normal_page(vma, addr, ptent); > + if (!page) > + continue; plz check if (!page || !page_mapped(page)) continue; > + > + if (PageAnon(page) && move_anon) > + ; > + else > + continue; Bad if ;) > + > + pc = lookup_page_cgroup(page); > + lock_page_cgroup(pc); > + if (!PageCgroupUsed(pc) || pc->mem_cgroup != mc->from) { > + unlock_page_cgroup(pc); > + continue; > + } > + unlock_page_cgroup(pc); > + > + if (!get_page_unless_zero(page)) > + continue; > + > + if (!isolate_lru_page(page)) > + list_add_tail(&page->lru, &list); > + else > + put_page(page); > + } > + pte_unmap_unlock(pte - 1, ptl); > + cond_resched(); > + > + if (!list_empty(&list)) > + list_for_each_entry_safe(page, tmp, &list, lru) { > + struct mem_cgroup *mem = mc->to; > + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, > + false, page); > + if (ret || !mem) > + break; > + list_move_tail(&page->lru, &mc->list); > + cond_resched(); need cond_resched() here ? > + } > + > + /* > + * We should put back all pages which remain on "list". > + * This means try_charge above has failed. > + * Pages which have been moved to mc->list would be put back at > + * clear_migrate_charge. > + */ > + if (!list_empty(&list)) > + list_for_each_entry_safe(page, tmp, &list, lru) { > + list_del(&page->lru); > + putback_lru_page(page); > + put_page(page); I wonder this put_page() is not necessary. > + } > + > + return ret; > +} > + > +static int migrate_charge_prepare(void) > +{ > + int ret = 0; > + struct mm_struct *mm; > + struct vm_area_struct *vma; > + > + mm = get_task_mm(mc->tsk); > + if (!mm) > + return 0; > + > + down_read(&mm->mmap_sem); > + for (vma = mm->mmap; vma; vma = vma->vm_next) { > + struct mm_walk migrate_charge_walk = { > + .pmd_entry = migrate_charge_prepare_pte_range, > + .mm = mm, > + .private = vma, > + }; > + if (signal_pending(current)) { > + ret = -EINTR; > + break; > + } > + if (is_vm_hugetlb_page(vma)) > + continue; > + /* We migrate charge of private pages for now */ > + if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) > + continue; > + if (mc->to->migrate_charge) { > + ret = walk_page_range(vma->vm_start, vma->vm_end, > + &migrate_charge_walk); > + if (ret) > + break; > + } > + } > + up_read(&mm->mmap_sem); > + > + mmput(mm); Hmm, Does this means a thread which is moved can continue its work and newly allocated pages will remain in old group ? > + return ret; > +} > + > +static void mem_cgroup_clear_migrate_charge(void) > +{ > + struct page *page, *tmp; > + > + VM_BUG_ON(!mc); > + > + if (!list_empty(&mc->list)) I think list_for_each_entry_safe() handles empty case. > + list_for_each_entry_safe(page, tmp, &mc->list, lru) { > + mem_cgroup_cancel_charge(mc->to); > + list_del(&page->lru); > + putback_lru_page(page); > + put_page(page); > + } > + > + kfree(mc); > + mc = NULL; > +} > + > static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, > struct task_struct *p) > { > - return 0; > + int ret; > + struct mem_cgroup *from = mem_cgroup_from_task(p); > + > + VM_BUG_ON(mc); > + > + if (from == mem) > + return 0; > + > + mc = kmalloc(sizeof(struct migrate_charge), GFP_KERNEL); > + if (!mc) > + return -ENOMEM; > + > + mc->tsk = p; > + mc->from = from; > + mc->to = mem; > + INIT_LIST_HEAD(&mc->list); > + > + ret = migrate_charge_prepare(); > + > + if (ret) > + mem_cgroup_clear_migrate_charge(); > + return ret; > } > > static int mem_cgroup_can_attach(struct cgroup_subsys *ss, > @@ -3207,10 +3376,35 @@ static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, > struct task_struct *p, > bool threadgroup) > { > + if (mc) > + mem_cgroup_clear_migrate_charge(); > } > > static void mem_cgroup_migrate_charge(void) > { > + struct page *page, *tmp; > + struct page_cgroup *pc; > + > + if (!mc) > + return; > + > + if (!list_empty(&mc->list)) > + list_for_each_entry_safe(page, tmp, &mc->list, lru) { > + pc = lookup_page_cgroup(page); > + lock_page_cgroup(pc); > + if (PageCgroupUsed(pc) && pc->mem_cgroup == mc->from) { > + mem_cgroup_move_account(pc, mc->from, mc->to); > + /* drop extra refcnt by try_charge() */ > + css_put(&mc->to->css); > + list_del(&page->lru); > + putback_lru_page(page); > + put_page(page); > + } > + unlock_page_cgroup(pc); > + cond_resched(); > + } > + > + mem_cgroup_clear_migrate_charge(); > } > Okay, them, if other subsystem fails "can_attach()", migrated charges are not moved back to original group. Right ? My biggest concern in this implementation is this "isolate" pages too much. Could you modify the whole routine as... struct migrate_charge { struct task_struct *tsk; struct mem_cgroup *from; struct mem_cgroup *to; struct list_head list; long charged; long committed; }; - mem_cgroup_can_migrate_charge() .... count pages and do "charge", no page isolation. and remember the number of charges as mc->charged++; - mem_cgroup_migrate_charge() - scan vmas/page table again. And isolate pages in fine grain. (256 pages per scan..or some small number) - migrate pages if success mc->committed++ after move, uncharge (mc->charged - mc->commited) Maybe you can find better one. But isolating all pages of process at once is a big hammber for vm, OOM. Thanks, -Kame > static void mem_cgroup_move_task(struct cgroup_subsys *ss, > -- 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/ . 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