From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 028AB6B004D for ; Thu, 24 Sep 2009 03:24:30 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n8O7OaoS009617 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 24 Sep 2009 16:24:36 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 71F9345DE50 for ; Thu, 24 Sep 2009 16:24:36 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 4865C45DE4E for ; Thu, 24 Sep 2009 16:24:36 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 29A3CE08005 for ; Thu, 24 Sep 2009 16:24:36 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 639E7E38008 for ; Thu, 24 Sep 2009 16:24:34 +0900 (JST) Date: Thu, 24 Sep 2009 16:22:26 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH 5/8] memcg: migrate charge of mapped page Message-Id: <20090924162226.5c703903.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090924144808.6a0d5140.nishimura@mxp.nes.nec.co.jp> References: <20090917112304.6cd4e6f6.nishimura@mxp.nes.nec.co.jp> <20090917160103.1bcdddee.nishimura@mxp.nes.nec.co.jp> <20090924144214.508469d1.nishimura@mxp.nes.nec.co.jp> <20090924144808.6a0d5140.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, 24 Sep 2009 14:48:08 +0900 Daisuke Nishimura wrote: > This patch is the core part of this charge migration feature. > It adds functions to migrate charge of pages mapped by the task. > > Implementation: > - define struct migrate_charge and a valuable of it(mc) 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 mc->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 mc->precharge > 0 on failure or at the end of charge > migration. > At first, thank you for hearing my request :) > Signed-off-by: Daisuke Nishimura > --- > mm/memcontrol.c | 270 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 files changed, 268 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 30499d9..fbcc195 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) > > +/* > + * Variables for charge migration 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; > + unsigned long precharge; > +}; > +static struct migrate_charge *mc; > + I associate migrate with "page migration". Then, hmm, recharge or move_charge or some other good word, I like. BTW, why "mc" is a global vairable ? IIUC, this all migration is done under cgroup_lock, mc can be global variable...right ? But ah..ok, this is a similar thing around cpuset's migration.. When you removing RFC, I'd like to see some performance cost information around this recharge.. > 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); > @@ -1362,7 +1376,7 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, > if (soft_fail_res) { > mem_over_soft_limit = > mem_cgroup_from_res_counter(soft_fail_res, res); > - if (mem_cgroup_soft_limit_check(mem_over_soft_limit)) > + if (page && mem_cgroup_soft_limit_check(mem_over_soft_limit)) > mem_cgroup_update_tree(mem_over_soft_limit, page); > } > done: > @@ -3197,10 +3211,167 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss, > return ret; > } > > +/* Handlers for charge migration at task move. */ > +/** > + * is_target_pte_for_migration - check a pte whether it is target for migration > + * @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(MIGRATION_TARGET_NONE): if the pte is not a target for charge migration. > + * 1(MIGRATION_TARGET_PAGE): if the page corresponding to this pte is a target > + * for charge migration. if @target is not NULL, the page is stored in > + * target->page with extra refcnt got(Callers should handle it). Will these type incrase more ? If not, bool value is enough. > + * > + * Called with pte lock held. > + */ > +union migration_target { > + struct page *page; > +}; > + > +enum migration_target_type { > + MIGRATION_TARGET_NONE, /* not used */ > + MIGRATION_TARGET_PAGE, > +}; > + > +static int is_target_pte_for_migration(struct vm_area_struct *vma, > + unsigned long addr, pte_t ptent, union migration_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; > + if (!get_page_unless_zero(page)) > + return 0; Is this necessary ? We're udner page table lock. Then, no one can unmap this. > + > + pc = lookup_page_cgroup(page); > + lock_page_cgroup(pc); Hmm...we may even avoid this lock. sounds tricy but we're under page_table_lock, no one can numap this. > + if (PageCgroupUsed(pc) && pc->mem_cgroup == mc->from) { > + ret = MIGRATION_TARGET_PAGE; > + if (target) > + target->page = page; > + } > + unlock_page_cgroup(pc); > + > + if (!ret || !target) > + put_page(page); > + > + return ret; > +} > + > +static int migrate_charge_do_precharge(void) > +{ > + int ret = -ENOMEM; > + struct mem_cgroup *mem = mc->to; > + > + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false, NULL); > + if (ret || !mem) > + return -ENOMEM; > + > + mc->precharge++; > + 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; > + 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_migration(vma, addr, *pte, NULL)) > + count++; > + pte_unmap_unlock(pte - 1, ptl); > + > + while (count-- && !ret) > + ret = migrate_charge_do_precharge(); > + > + 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_prepare_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; > + ret = walk_page_range(vma->vm_start, vma->vm_end, > + &migrate_charge_prepare_walk); > + if (ret) > + break; > + cond_resched(); > + } > + up_read(&mm->mmap_sem); > + > + mmput(mm); > + return ret; > +} > + > +static void mem_cgroup_clear_migrate_charge(void) > +{ > + VM_BUG_ON(!mc); > + > + while (mc->precharge--) > + __mem_cgroup_cancel_charge(mc->to); > + 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; > + please VM_BUG_ON(!mc); > + mc = kmalloc(sizeof(struct migrate_charge), GFP_KERNEL); > + if (!mc) > + return -ENOMEM; > + > + mc->tsk = p; > + mc->from = from; > + mc->to = mem; > + mc->precharge = 0; > + > + ret = migrate_charge_prepare(); > + > + if (ret) > + mem_cgroup_clear_migrate_charge(); > + return ret; > } > > static int mem_cgroup_can_attach(struct cgroup_subsys *ss, > @@ -3220,10 +3391,105 @@ static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, > struct task_struct *p, > bool threadgroup) > { > + if (mc) > + mem_cgroup_clear_migrate_charge(); > +} > + > +static int migrate_charge_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 migration_target target; > + int type; > + struct page *page; > + struct page_cgroup *pc; > + > + if (!mc->precharge) > + break; > + > + type = is_target_pte_for_migration(vma, addr, ptent, &target); > + switch (type) { > + case MIGRATION_TARGET_PAGE: > + page = target.page; > + if (isolate_lru_page(page)) > + goto put; > + pc = lookup_page_cgroup(page); > + if (!mem_cgroup_move_account(pc, mc->from, mc->to)) { > + css_put(&mc->to->css); > + mc->precharge--; > + } > + putback_lru_page(page); > +put: /* is_target_pte_for_migration() 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 charge migration if we have failed in > + * precharge once in attach() phase. > + */ > + ret = migrate_charge_do_precharge(); > + if (!ret) > + goto retry; I think this is a nice handling. > + } > + > + return ret; > } > > static void mem_cgroup_migrate_charge(void) > { > + struct mm_struct *mm; > + struct vm_area_struct *vma; > + > + if (!mc) > + return; > + > + mm = get_task_mm(mc->tsk); > + if (!mm) > + goto out; > + > + lru_add_drain_all(); > + down_read(&mm->mmap_sem); > + for (vma = mm->mmap; vma; vma = vma->vm_next) { > + int ret; > + struct mm_walk migrate_charge_walk = { > + .pmd_entry = migrate_charge_pte_range, > + .mm = mm, > + .private = vma, > + }; > + if (is_vm_hugetlb_page(vma)) > + continue; > + ret = walk_page_range(vma->vm_start, vma->vm_end, > + &migrate_charge_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); > +out: > + mem_cgroup_clear_migrate_charge(); > } > > static void mem_cgroup_move_task(struct cgroup_subsys *ss, > -- Hmm, I don't complain to this patch itself but cgroup_lock() will be the last wall to be overcomed for production use... Can't we just prevent rmdir/mkdir on a hierarchy and move a task ? fork() etc..can be stopped by this and cpuset's code is not very good. 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