From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 53D678E0001 for ; Tue, 11 Sep 2018 20:44:54 -0400 (EDT) Received: by mail-pf1-f198.google.com with SMTP id o27-v6so123953pfj.6 for ; Tue, 11 Sep 2018 17:44:54 -0700 (PDT) Received: from mga04.intel.com (mga04.intel.com. [192.55.52.120]) by mx.google.com with ESMTPS id d12-v6si21574651pla.421.2018.09.11.17.44.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Sep 2018 17:44:53 -0700 (PDT) From: Huang Ying Subject: [PATCH -V5 RESEND 11/21] swap: Add sysfs interface to configure THP swapin Date: Wed, 12 Sep 2018 08:44:04 +0800 Message-Id: <20180912004414.22583-12-ying.huang@intel.com> In-Reply-To: <20180912004414.22583-1-ying.huang@intel.com> References: <20180912004414.22583-1-ying.huang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , "Kirill A. Shutemov" , Andrea Arcangeli , Michal Hocko , Johannes Weiner , Shaohua Li , Hugh Dickins , Minchan Kim , Rik van Riel , Dave Hansen , Naoya Horiguchi , Zi Yan , Daniel Jordan Swapin a THP as a whole isn't desirable in some situations. For example, for completely random access pattern, swapin a THP in one piece will inflate the reading greatly. So a sysfs interface: /sys/kernel/mm/transparent_hugepage/swapin_enabled is added to configure it. Three options as follow are provided, - always: THP swapin will be enabled always - madvise: THP swapin will be enabled only for VMA with VM_HUGEPAGE flag set. - never: THP swapin will be disabled always The default configuration is: madvise. During page fault, if a PMD swap mapping is found and THP swapin is disabled, the huge swap cluster and the PMD swap mapping will be split and fallback to normal page swapin. Signed-off-by: "Huang, Ying" Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Michal Hocko Cc: Johannes Weiner Cc: Shaohua Li Cc: Hugh Dickins Cc: Minchan Kim Cc: Rik van Riel Cc: Dave Hansen Cc: Naoya Horiguchi Cc: Zi Yan Cc: Daniel Jordan --- Documentation/admin-guide/mm/transhuge.rst | 21 +++++++ include/linux/huge_mm.h | 31 ++++++++++ mm/huge_memory.c | 94 ++++++++++++++++++++++++------ 3 files changed, 127 insertions(+), 19 deletions(-) diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index 85e33f785fd7..23aefb17101c 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -160,6 +160,27 @@ Some userspace (such as a test program, or an optimized memory allocation cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size +Transparent hugepage may be swapout and swapin in one piece without +splitting. This will improve the utility of transparent hugepage but +may inflate the read/write too. So whether to enable swapin +transparent hugepage in one piece can be configured as follow. + + echo always >/sys/kernel/mm/transparent_hugepage/swapin_enabled + echo madvise >/sys/kernel/mm/transparent_hugepage/swapin_enabled + echo never >/sys/kernel/mm/transparent_hugepage/swapin_enabled + +always + Attempt to allocate a transparent huge page and read it from + swap space in one piece every time. + +never + Always split the swap space and PMD swap mapping and swapin + the fault normal page during swapin. + +madvise + Only swapin the transparent huge page in one piece for + MADV_HUGEPAGE madvise regions. + khugepaged will be automatically started when transparent_hugepage/enabled is set to "always" or "madvise, and it'll be automatically shutdown if it's set to "never". diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index c2b8ced6fc2b..9dedff974def 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -63,6 +63,8 @@ enum transparent_hugepage_flag { #ifdef CONFIG_DEBUG_VM TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG, #endif + TRANSPARENT_HUGEPAGE_SWAPIN_FLAG, + TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG, }; struct kobject; @@ -405,11 +407,40 @@ static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) #ifdef CONFIG_THP_SWAP extern int do_huge_pmd_swap_page(struct vm_fault *vmf, pmd_t orig_pmd); + +static inline bool transparent_hugepage_swapin_enabled( + struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_NOHUGEPAGE) + return false; + + if (is_vma_temporary_stack(vma)) + return false; + + if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) + return false; + + if (transparent_hugepage_flags & + (1 << TRANSPARENT_HUGEPAGE_SWAPIN_FLAG)) + return true; + + if (transparent_hugepage_flags & + (1 << TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG)) + return !!(vma->vm_flags & VM_HUGEPAGE); + + return false; +} #else /* CONFIG_THP_SWAP */ static inline int do_huge_pmd_swap_page(struct vm_fault *vmf, pmd_t orig_pmd) { return 0; } + +static inline bool transparent_hugepage_swapin_enabled( + struct vm_area_struct *vma) +{ + return false; +} #endif /* CONFIG_THP_SWAP */ #endif /* _LINUX_HUGE_MM_H */ diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1232ade5deca..c4a766243a8f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -57,7 +57,8 @@ unsigned long transparent_hugepage_flags __read_mostly = #endif (1<address); if (!page) { + if (!transparent_hugepage_swapin_enabled(vma)) + goto split; + page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE, vma, haddr, false); if (!page) { @@ -1660,24 +1714,8 @@ int do_huge_pmd_swap_page(struct vm_fault *vmf, pmd_t orig_pmd) * Back out if somebody else faulted in this pmd * while we released the pmd lock. */ - if (likely(pmd_same(*vmf->pmd, orig_pmd))) { - /* - * Failed to allocate huge page, split huge swap - * cluster, and fallback to swapin normal page - */ - ret = split_swap_cluster(entry, 0); - /* Somebody else swapin the swap entry, retry */ - if (ret == -EEXIST) { - ret = 0; - goto retry; - /* swapoff occurs under us */ - } else if (ret == -EINVAL) - ret = 0; - else { - count_vm_event(THP_SWPIN_FALLBACK); - goto fallback; - } - } + if (likely(pmd_same(*vmf->pmd, orig_pmd))) + goto split; delayacct_clear_flag(DELAYACCT_PF_SWAPIN); goto out; } @@ -1790,6 +1828,24 @@ int do_huge_pmd_swap_page(struct vm_fault *vmf, pmd_t orig_pmd) if (page) put_page(page); return ret; +split: + /* + * Failed to allocate huge page, split huge swap cluster, and + * fallback to swapin normal page + */ + ret = split_swap_cluster(entry, 0); + /* Somebody else swapin the swap entry, retry */ + if (ret == -EEXIST) { + ret = 0; + goto retry; + } + /* swapoff occurs under us */ + if (ret == -EINVAL) { + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + return 0; + } + count_vm_event(THP_SWPIN_FALLBACK); + goto fallback; } #endif -- 2.16.4