From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754722Ab1A1Ded (ORCPT ); Thu, 27 Jan 2011 22:34:33 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:51647 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754610Ab1A1Dec (ORCPT ); Thu, 27 Jan 2011 22:34:32 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 28 Jan 2011 12:28:32 +0900 From: KAMEZAWA Hiroyuki To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "hannes@cmpxchg.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" Subject: [BUGFIX][PATCH 4/4] memcg: fix khugepaged should skip busy memcg Message-Id: <20110128122832.34550412.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> References: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: KAMEZAWA Hiroyuki When using khugepaged with small memory cgroup, we see khugepaged causes soft lockup, or running process under memcg will hang It's because khugepaged tries to scan all pmd of a process which is under busy/small memory cgroup and tries to allocate HUGEPAGE size resource. This work is done under mmap_sem and can cause memory reclaim repeatedly. This will easily raise cpu usage of khugepaged and latecy of scanned process will goes up. Moreover, it seems succesfully working TransHuge pages may be splitted by this memory reclaim caused by khugepaged. This patch adds a hint for khugepaged whether a process is under a memory cgroup which has sufficient memory. If memcg seems busy, a process is skipped. How to test: # mount -o cgroup cgroup /cgroup/memory -o memory # mkdir /cgroup/memory/A # echo 200M (or some small) > /cgroup/memory/A/memory.limit_in_bytes # echo 0 > /cgroup/memory/A/tasks # make -j 8 kernel Signed-off-by: KAMEZAWA Hiroyuki --- include/linux/memcontrol.h | 7 +++++ mm/huge_memory.c | 10 +++++++- mm/memcontrol.c | 53 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 69 insertions(+), 1 deletion(-) Index: mmotm-0125/mm/memcontrol.c =================================================================== --- mmotm-0125.orig/mm/memcontrol.c +++ mmotm-0125/mm/memcontrol.c @@ -255,6 +255,9 @@ struct mem_cgroup { /* For oom notifier event fd */ struct list_head oom_notify; + /* For transparent hugepage daemon */ + unsigned long long recent_failcnt; + /* * Should we move charges of a task when a task is moved into this * mem_cgroup ? And what type of charges should we move ? @@ -2214,6 +2217,56 @@ void mem_cgroup_split_huge_fixup(struct tail_pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT; move_unlock_page_cgroup(head_pc, &flags); } + +bool mem_cgroup_worth_try_hugepage_scan(struct mm_struct *mm) +{ + struct mem_cgroup *mem; + bool ret = true; + u64 recent_charge_fail; + + if (mem_cgroup_disabled()) + return true; + + mem = try_get_mem_cgroup_from_mm(mm); + + if (!mem) + return true; + + if (mem_cgroup_is_root(mem)) + goto out; + + /* + * At collapsing, khugepaged charges HPAGE_SIZE. When it unmap + * used ptes, the charge will be decreased. + * + * This requirement of 'extra charge' at collapsing seems redundant + * it's safe way for now. For example, at replacing a chunk of page + * to be hugepage, khuepaged skips pte_none() entry, which is not + * which is not charged. But we should do charge under spinlocks as + * pte_lock, we need precharge. Check status before doing heavy + * jobs and give khugepaged chance to retire early. + */ + if (mem_cgroup_check_margin(mem) >= HPAGE_SIZE) + ret = false; + + /* + * This is an easy check. If someone other than khugepaged does + * hit limit, khugepaged should avoid more pressure. + */ + recent_charge_fail = res_counter_read_u64(&mem->res, RES_FAILCNT); + if (ret + && mem->recent_failcnt + && recent_charge_fail > mem->recent_failcnt) { + ret = false; + } + /* because this thread will fail charge by itself +1.*/ + if (recent_charge_fail) + mem->recent_failcnt = recent_charge_fail + 1; +out: + css_put(&mem->css); + return ret; +} + #endif /** Index: mmotm-0125/mm/huge_memory.c =================================================================== --- mmotm-0125.orig/mm/huge_memory.c +++ mmotm-0125/mm/huge_memory.c @@ -2011,8 +2011,10 @@ static unsigned int khugepaged_scan_mm_s down_read(&mm->mmap_sem); if (unlikely(khugepaged_test_exit(mm))) vma = NULL; - else + else if (mem_cgroup_worth_try_hugepage_scan(mm)) vma = find_vma(mm, khugepaged_scan.address); + else + vma = NULL; progress++; for (; vma; vma = vma->vm_next) { @@ -2024,6 +2026,12 @@ static unsigned int khugepaged_scan_mm_s break; } + if (unlikely(!mem_cgroup_worth_try_hugepage_scan(mm))) { + progress++; + vma = NULL; /* try next mm */ + break; + } + if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || (vma->vm_flags & VM_NOHUGEPAGE)) { Index: mmotm-0125/include/linux/memcontrol.h =================================================================== --- mmotm-0125.orig/include/linux/memcontrol.h +++ mmotm-0125/include/linux/memcontrol.h @@ -148,6 +148,7 @@ u64 mem_cgroup_get_limit(struct mem_cgro #ifdef CONFIG_TRANSPARENT_HUGEPAGE void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail); +bool mem_cgroup_worth_try_hugepage_scan(struct mm_struct *mm); #endif #else /* CONFIG_CGROUP_MEM_RES_CTLR */ @@ -342,6 +343,12 @@ u64 mem_cgroup_get_limit(struct mem_cgro static inline void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail) { + +} + +static inline bool mem_cgroup_worth_try_hugepage_scan(struct mm_struct *mm) +{ + return true; } #endif /* CONFIG_CGROUP_MEM_CONT */ 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 SMTP id 1852C8D0039 for ; Thu, 27 Jan 2011 22:34:34 -0500 (EST) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id D84293EE0BD for ; Fri, 28 Jan 2011 12:34:31 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id BEAB945DE59 for ; Fri, 28 Jan 2011 12:34:31 +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 A5BC045DE56 for ; Fri, 28 Jan 2011 12:34:31 +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 9839E1DB803E for ; Fri, 28 Jan 2011 12:34:31 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 543F81DB8037 for ; Fri, 28 Jan 2011 12:34:31 +0900 (JST) Date: Fri, 28 Jan 2011 12:28:32 +0900 From: KAMEZAWA Hiroyuki Subject: [BUGFIX][PATCH 4/4] memcg: fix khugepaged should skip busy memcg Message-Id: <20110128122832.34550412.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> References: <20110128122229.6a4c74a2.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "hannes@cmpxchg.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" List-ID: From: KAMEZAWA Hiroyuki When using khugepaged with small memory cgroup, we see khugepaged causes soft lockup, or running process under memcg will hang It's because khugepaged tries to scan all pmd of a process which is under busy/small memory cgroup and tries to allocate HUGEPAGE size resource. This work is done under mmap_sem and can cause memory reclaim repeatedly. This will easily raise cpu usage of khugepaged and latecy of scanned process will goes up. Moreover, it seems succesfully working TransHuge pages may be splitted by this memory reclaim caused by khugepaged. This patch adds a hint for khugepaged whether a process is under a memory cgroup which has sufficient memory. If memcg seems busy, a process is skipped. How to test: # mount -o cgroup cgroup /cgroup/memory -o memory # mkdir /cgroup/memory/A # echo 200M (or some small) > /cgroup/memory/A/memory.limit_in_bytes # echo 0 > /cgroup/memory/A/tasks # make -j 8 kernel Signed-off-by: KAMEZAWA Hiroyuki --- include/linux/memcontrol.h | 7 +++++ mm/huge_memory.c | 10 +++++++- mm/memcontrol.c | 53 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 69 insertions(+), 1 deletion(-) Index: mmotm-0125/mm/memcontrol.c =================================================================== --- mmotm-0125.orig/mm/memcontrol.c +++ mmotm-0125/mm/memcontrol.c @@ -255,6 +255,9 @@ struct mem_cgroup { /* For oom notifier event fd */ struct list_head oom_notify; + /* For transparent hugepage daemon */ + unsigned long long recent_failcnt; + /* * Should we move charges of a task when a task is moved into this * mem_cgroup ? And what type of charges should we move ? @@ -2214,6 +2217,56 @@ void mem_cgroup_split_huge_fixup(struct tail_pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT; move_unlock_page_cgroup(head_pc, &flags); } + +bool mem_cgroup_worth_try_hugepage_scan(struct mm_struct *mm) +{ + struct mem_cgroup *mem; + bool ret = true; + u64 recent_charge_fail; + + if (mem_cgroup_disabled()) + return true; + + mem = try_get_mem_cgroup_from_mm(mm); + + if (!mem) + return true; + + if (mem_cgroup_is_root(mem)) + goto out; + + /* + * At collapsing, khugepaged charges HPAGE_SIZE. When it unmap + * used ptes, the charge will be decreased. + * + * This requirement of 'extra charge' at collapsing seems redundant + * it's safe way for now. For example, at replacing a chunk of page + * to be hugepage, khuepaged skips pte_none() entry, which is not + * which is not charged. But we should do charge under spinlocks as + * pte_lock, we need precharge. Check status before doing heavy + * jobs and give khugepaged chance to retire early. + */ + if (mem_cgroup_check_margin(mem) >= HPAGE_SIZE) + ret = false; + + /* + * This is an easy check. If someone other than khugepaged does + * hit limit, khugepaged should avoid more pressure. + */ + recent_charge_fail = res_counter_read_u64(&mem->res, RES_FAILCNT); + if (ret + && mem->recent_failcnt + && recent_charge_fail > mem->recent_failcnt) { + ret = false; + } + /* because this thread will fail charge by itself +1.*/ + if (recent_charge_fail) + mem->recent_failcnt = recent_charge_fail + 1; +out: + css_put(&mem->css); + return ret; +} + #endif /** Index: mmotm-0125/mm/huge_memory.c =================================================================== --- mmotm-0125.orig/mm/huge_memory.c +++ mmotm-0125/mm/huge_memory.c @@ -2011,8 +2011,10 @@ static unsigned int khugepaged_scan_mm_s down_read(&mm->mmap_sem); if (unlikely(khugepaged_test_exit(mm))) vma = NULL; - else + else if (mem_cgroup_worth_try_hugepage_scan(mm)) vma = find_vma(mm, khugepaged_scan.address); + else + vma = NULL; progress++; for (; vma; vma = vma->vm_next) { @@ -2024,6 +2026,12 @@ static unsigned int khugepaged_scan_mm_s break; } + if (unlikely(!mem_cgroup_worth_try_hugepage_scan(mm))) { + progress++; + vma = NULL; /* try next mm */ + break; + } + if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || (vma->vm_flags & VM_NOHUGEPAGE)) { Index: mmotm-0125/include/linux/memcontrol.h =================================================================== --- mmotm-0125.orig/include/linux/memcontrol.h +++ mmotm-0125/include/linux/memcontrol.h @@ -148,6 +148,7 @@ u64 mem_cgroup_get_limit(struct mem_cgro #ifdef CONFIG_TRANSPARENT_HUGEPAGE void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail); +bool mem_cgroup_worth_try_hugepage_scan(struct mm_struct *mm); #endif #else /* CONFIG_CGROUP_MEM_RES_CTLR */ @@ -342,6 +343,12 @@ u64 mem_cgroup_get_limit(struct mem_cgro static inline void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail) { + +} + +static inline bool mem_cgroup_worth_try_hugepage_scan(struct mm_struct *mm) +{ + return true; } #endif /* CONFIG_CGROUP_MEM_CONT */ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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