From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 119296B006A for ; Fri, 6 Nov 2009 00:32:53 -0500 (EST) Date: Fri, 6 Nov 2009 14:14:48 +0900 From: Daisuke Nishimura Subject: [PATCH -mmotm 6/8] memcg: recharge charges of anonymous page Message-Id: <20091106141448.6548687a.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20091106141011.3ded1551.nishimura@mxp.nes.nec.co.jp> References: <20091106141011.3ded1551.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: linux-mm Cc: Andrew Morton , Balbir Singh , KAMEZAWA Hiroyuki , Li Zefan , Paul Menage , Daisuke Nishimura List-ID: This patch is the core part of this recharge-at-task-move feature. It implements functions to recharge charges of anonymous pages mapped only by the target task. Implementation: - define struct recharge_struct and a valuable of it(recharge) to remember the count of pre-charges and other information. - At can_attach(), parse the page table of the task and count the number of mapped pages which are charged to the source mem_cgroup, and call __mem_cgroup_try_charge() repeatedly and count up recharge.precharge. - At attach(), parse the page table again, find a target page as we did in can_attach(), and call mem_cgroup_move_account() about the page. - Cancel all charges if recharge.precharge > 0 on failure or at the end of task move. Signed-off-by: Daisuke Nishimura --- Documentation/cgroups/memory.txt | 36 +++++- mm/memcontrol.c | 275 +++++++++++++++++++++++++++++++++++++- 2 files changed, 306 insertions(+), 5 deletions(-) diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index b871f25..54281ff 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -262,10 +262,12 @@ some of the pages cached in the cgroup (page cache pages). 4.2 Task migration When a task migrates from one cgroup to another, it's charge is not -carried forward. The pages allocated from the original cgroup still +carried forward by default. The pages allocated from the original cgroup still remain charged to it, the charge is dropped when the page is freed or reclaimed. +Note: You can move charges of a task along with task migration. See 8. + 4.3 Removing a cgroup A cgroup can be removed by rmdir, but as discussed in sections 4.1 and 4.2, a @@ -414,7 +416,37 @@ NOTE1: Soft limits take effect over a long period of time, since they involve NOTE2: It is recommended to set the soft limit always below the hard limit, otherwise the hard limit will take precedence. -8. TODO +8. Recharge at task move + +Users can move charges associated with a task along with task move, that is, +uncharge from the old cgroup and charge to the new cgroup. + +8.1 Interface + +This feature is disabled by default. It can be enabled(and disabled again) by +writing to memory.recharge_at_immigrate of the destination cgroup. + +If you want to enable it + +# echo 1 > memory.recharget_at_immigrate + +Note: A value more than 1 will be supported in futer. See 8.2. + +And if you want disable it again + +# echo 0 > memory.recharget_at_immigrate + +8.2 Type of charges which can be recharged + +We recharge a charge which meets the following conditions. + +a. It must be charged to the old cgroup. +b. A charge of an anonymous page used by the target task. The page must be used + only by the target task. + +Note: More type of pages(e.g. file cache, shmem,) will be supported in future. + +9. TODO 1. Add support for accounting huge pages (as a separate controller) 2. Make per-cgroup scanner reclaim not-shared pages first diff --git a/mm/memcontrol.c b/mm/memcontrol.c index afa1179..f4b7116 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -21,6 +21,8 @@ #include #include #include +#include +#include #include #include #include @@ -239,6 +241,18 @@ struct mem_cgroup { }; /* + * A data structure and a valiable for recharging charges at task move. + * "recharge" and its members are protected by cgroup_lock + */ +struct recharge_struct { + struct mem_cgroup *from; + struct mem_cgroup *to; + struct task_struct *target; /* the target task being moved */ + unsigned long precharge; +}; +static struct recharge_struct recharge; + +/* * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft * limit reclaim to prevent infinite loops, if they ever occur. */ @@ -1496,7 +1510,7 @@ charged: * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree. * if they exceeds softlimit. */ - if (mem_cgroup_soft_limit_check(mem)) + if (page && mem_cgroup_soft_limit_check(mem)) mem_cgroup_update_tree(mem, page); done: return 0; @@ -3416,10 +3430,170 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss, } /* Handlers for recharge at task move. */ +/** + * is_target_pte_for_recharge - check a pte whether it is valid for recharge + * @vma: the vma the pte to be checked belongs + * @addr: the address corresponding to the pte to be checked + * @ptent: the pte to be checked + * @target: the pointer the target page will be stored(can be NULL) + * + * Returns + * 0(RECHARGE_TARGET_NONE): if the pte is not a target for recharge. + * 1(RECHARGE_TARGET_PAGE): if the page corresponding to this pte is a target + * for recharge. if @target is not NULL, the page is stored in target->page + * with extra refcnt got(Callers should handle it). + * + * Called with pte lock held. + */ +/* We add a new member later. */ +union recharge_target { + struct page *page; +}; + +/* We add a new type later. */ +enum recharge_target_type { + RECHARGE_TARGET_NONE, /* not used */ + RECHARGE_TARGET_PAGE, +}; + +static int is_target_pte_for_recharge(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent, union recharge_target *target) +{ + struct page *page; + struct page_cgroup *pc; + int ret = 0; + + if (!pte_present(ptent)) + return 0; + + page = vm_normal_page(vma, addr, ptent); + if (!page || !page_mapped(page)) + return 0; + /* TODO: We don't recharge file(including shmem/tmpfs) pages for now. */ + if (!PageAnon(page)) + return 0; + /* + * TODO: We don't recharge shared(used by multiple processes) pages + * for now. + */ + if (page_mapcount(page) > 1) + return 0; + if (!get_page_unless_zero(page)) + return 0; + + pc = lookup_page_cgroup(page); + lock_page_cgroup(pc); + if (PageCgroupUsed(pc) && pc->mem_cgroup == recharge.from) { + ret = RECHARGE_TARGET_PAGE; + if (target) + target->page = page; + } + unlock_page_cgroup(pc); + + if (!ret || !target) + put_page(page); + + return ret; +} + +static int mem_cgroup_recharge_do_precharge(void) +{ + int ret = -ENOMEM; + struct mem_cgroup *mem = recharge.to; + + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false, NULL); + if (ret || !mem) + return -ENOMEM; + + recharge.precharge++; + return ret; +} + +static int mem_cgroup_recharge_prepare_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + int ret = 0; + unsigned long count = 0; + struct vm_area_struct *vma = walk->private; + pte_t *pte; + spinlock_t *ptl; + + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (; addr != end; pte++, addr += PAGE_SIZE) + if (is_target_pte_for_recharge(vma, addr, *pte, NULL)) + count++; + pte_unmap_unlock(pte - 1, ptl); + + while (count-- && !ret) + ret = mem_cgroup_recharge_do_precharge(); + + return ret; +} + +static int mem_cgroup_recharge_prepare(void) +{ + int ret = 0; + struct mm_struct *mm; + struct vm_area_struct *vma; + + mm = get_task_mm(recharge.target); + if (!mm) + return 0; + + down_read(&mm->mmap_sem); + for (vma = mm->mmap; vma; vma = vma->vm_next) { + struct mm_walk mem_cgroup_recharge_prepare_walk = { + .pmd_entry = mem_cgroup_recharge_prepare_pte_range, + .mm = mm, + .private = vma, + }; + if (signal_pending(current)) { + ret = -EINTR; + break; + } + if (is_vm_hugetlb_page(vma)) + continue; + ret = walk_page_range(vma->vm_start, vma->vm_end, + &mem_cgroup_recharge_prepare_walk); + if (ret) + break; + cond_resched(); + } + up_read(&mm->mmap_sem); + + mmput(mm); + return ret; +} + +static void mem_cgroup_clear_recharge(void) +{ + while (recharge.precharge--) + mem_cgroup_cancel_charge(recharge.to); + recharge.from = NULL; + recharge.to = NULL; + recharge.target = NULL; +} + static int mem_cgroup_can_recharge(struct mem_cgroup *mem, struct task_struct *p) { - return 0; + int ret; + struct mem_cgroup *from = mem_cgroup_from_task(p); + + if (from == mem) + return 0; + + recharge.from = from; + recharge.to = mem; + recharge.target = p; + recharge.precharge = 0; + + ret = mem_cgroup_recharge_prepare(); + + if (ret) + mem_cgroup_clear_recharge(); + return ret; } static int mem_cgroup_can_attach(struct cgroup_subsys *ss, @@ -3442,11 +3616,104 @@ static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, struct task_struct *p, bool threadgroup) { + struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup); + mutex_unlock(&memcg_tasklist); + if (mem->recharge_at_immigrate && thread_group_leader(p)) + mem_cgroup_clear_recharge(); +} + +static int mem_cgroup_recharge_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + int ret = 0; + struct vm_area_struct *vma = walk->private; + pte_t *pte; + spinlock_t *ptl; + +retry: + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (; addr != end; addr += PAGE_SIZE) { + pte_t ptent = *(pte++); + union recharge_target target; + int type; + struct page *page; + struct page_cgroup *pc; + + if (!recharge.precharge) + break; + + type = is_target_pte_for_recharge(vma, addr, ptent, &target); + switch (type) { + case RECHARGE_TARGET_PAGE: + page = target.page; + if (isolate_lru_page(page)) + goto put; + pc = lookup_page_cgroup(page); + if (!mem_cgroup_move_account(pc, + recharge.from, recharge.to)) { + css_put(&recharge.to->css); + recharge.precharge--; + } + putback_lru_page(page); +put: /* is_target_pte_for_recharge() gets the page */ + put_page(page); + break; + default: + continue; + } + } + pte_unmap_unlock(pte - 1, ptl); + + if (addr != end) { + /* + * We have consumed all precharges we got in can_attach(). + * We try precharge one by one, but don't do any additional + * precharges nor recharges to recharge.to if we have failed in + * precharge once in attach() phase. + */ + ret = mem_cgroup_recharge_do_precharge(); + if (!ret) + goto retry; + } + + return ret; } static void mem_cgroup_recharge(void) { + struct mm_struct *mm; + struct vm_area_struct *vma; + + mm = get_task_mm(recharge.target); + if (!mm) + return; + + lru_add_drain_all(); + down_read(&mm->mmap_sem); + for (vma = mm->mmap; vma; vma = vma->vm_next) { + int ret; + struct mm_walk mem_cgroup_recharge_walk = { + .pmd_entry = mem_cgroup_recharge_pte_range, + .mm = mm, + .private = vma, + }; + if (is_vm_hugetlb_page(vma)) + continue; + ret = walk_page_range(vma->vm_start, vma->vm_end, + &mem_cgroup_recharge_walk); + if (ret) + /* + * means we have consumed all precharges and failed in + * doing additional precharge. Just abandon here. + */ + break; + cond_resched(); + } + up_read(&mm->mmap_sem); + + mmput(mm); } static void mem_cgroup_move_task(struct cgroup_subsys *ss, @@ -3458,8 +3725,10 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss, struct mem_cgroup *mem = mem_cgroup_from_cont(cont); mutex_unlock(&memcg_tasklist); - if (mem->recharge_at_immigrate && thread_group_leader(p)) + if (mem->recharge_at_immigrate && thread_group_leader(p)) { mem_cgroup_recharge(); + mem_cgroup_clear_recharge(); + } } struct cgroup_subsys mem_cgroup_subsys = { -- 1.5.6.1 -- 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