From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3255C4332F for ; Sun, 26 Sep 2021 20:13:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB9AA60EB6 for ; Sun, 26 Sep 2021 20:13:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230045AbhIZUPR (ORCPT ); Sun, 26 Sep 2021 16:15:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229894AbhIZUPQ (ORCPT ); Sun, 26 Sep 2021 16:15:16 -0400 Received: from mail-ed1-x532.google.com (mail-ed1-x532.google.com [IPv6:2a00:1450:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9A6DC061570; Sun, 26 Sep 2021 13:13:39 -0700 (PDT) Received: by mail-ed1-x532.google.com with SMTP id g7so664623edv.1; Sun, 26 Sep 2021 13:13:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Gx6lFxQkcmAA7UZaMrtFU5WcmTs0VRARHeMqyf6mMgw=; b=XOUsdZi6IfUisgHpPzVVzWp5nCMmSjn6dsArQ9my3vPzDWLoTpPzvtrxPnlHoBCpFK IBv86vElDr5xqJ4piN31W85NBPJLTLcgi1kxVIMAoYfeHdpDaVmFV7zUOm1pw2xGZZ0k SpuQyMfcXQpjoElHcMxSow2DEKjTzp6NoVr9TF2dbLsOnokvXkozayWbpCkq07JSZv/P XX76jsFR4zcFS0SjaGDXlx23QnsR1La6iN/bGlyYHvdod6cCLTc5RJoqZDyngmOR/T6o +xkcEbOnskxqXtn8Pal7BB6Q4Ph1yrRG3uDY3K1Bo2suXnlDgWD2KuW6VJWLZscHcdcl 2Tmg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Gx6lFxQkcmAA7UZaMrtFU5WcmTs0VRARHeMqyf6mMgw=; b=dTRy+m16THmGkdc8VpgwYGBu3CoZdQpj5ca8EiL2TozYV+uw1QAVUXKgZx2MGbur7J MRdZxjv9SZDKC3uaSqn+lxIBm/OV1Q2RK/u25x2b0riZ9snE2jo8wv4b5naUFGLVA67Y ekbqnQD4JdeJRO+QfhWBGeXD0whqOV8k6aQq4rtkorS0tdfn2HjKWrZfcVS1Y0Fz/dDJ 6MsHUu4YqCfFGfFZ0SYkfVFSUzxUzq3awuAXhOg+9KwsyHb97GKx2ZhoZj7jpZOoYkTI ssWPqgh/b0RwejuW7NSXB5qya/k6UdamtGpmAzyosVMBSnkoUmNlfoQEp+49cSeqD6pw uK0g== X-Gm-Message-State: AOAM530DgLcCxXvhDOpS4zq+B4yPKumebecwLdNWmK/8w+fKAE4wzt1F 35f/sOa2udE2FvwmND74c3tV/vAJsOd19Jom/yI= X-Google-Smtp-Source: ABdhPJz9/Pv7P2gR6ExTXpUFRabHHfvpk9V7zPQWM+yNAMmodQ395ri1yDMPSHB9Sv4PcvsD4/Dckh1MsG1PyBbVPj4= X-Received: by 2002:a50:c31c:: with SMTP id a28mr20040301edb.384.1632687218431; Sun, 26 Sep 2021 13:13:38 -0700 (PDT) MIME-Version: 1.0 References: <20210926031339.40043-1-songmuchun@bytedance.com> <20210926031339.40043-3-songmuchun@bytedance.com> In-Reply-To: <20210926031339.40043-3-songmuchun@bytedance.com> From: Barry Song <21cnbao@gmail.com> Date: Mon, 27 Sep 2021 09:13:27 +1300 Message-ID: Subject: Re: [PATCH v4 2/5] mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key To: Muchun Song Cc: Mike Kravetz , Andrew Morton , Oscar Salvador , Michal Hocko , Barry Song , David Hildenbrand , Chen Huang , "Bodeddula, Balasubramaniam" , Jonathan Corbet , Matthew Wilcox , Xiongchun duan , fam.zheng@bytedance.com, Muchun Song , Qi Zheng , linux-doc@vger.kernel.org, LKML , Linux-MM Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 26, 2021 at 4:15 PM Muchun Song wrote: > > The page_head_if_fake() is used throughout memory management and the > conditional check requires checking a global variable, although the > overhead of this check may be small, it increases when the memory > cache comes under pressure. Also, the global variable will not be > modified after system boot, so it is very appropriate to use static > key machanism. > > Signed-off-by: Muchun Song Reviewed-by: Barry Song > --- > include/linux/hugetlb.h | 6 ------ > include/linux/page-flags.h | 18 +++++++++++++++--- > mm/hugetlb_vmemmap.c | 12 ++++++------ > mm/memory_hotplug.c | 2 +- > 4 files changed, 22 insertions(+), 16 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 3cbf60464398..a90cc88195da 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -1055,12 +1055,6 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr > } > #endif /* CONFIG_HUGETLB_PAGE */ > > -#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP > -extern bool hugetlb_free_vmemmap_enabled; > -#else > -#define hugetlb_free_vmemmap_enabled false > -#endif > - > static inline spinlock_t *huge_pte_lock(struct hstate *h, > struct mm_struct *mm, pte_t *pte) > { > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index b49808e748ce..26e540fd3393 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -185,7 +185,14 @@ enum pageflags { > #ifndef __GENERATING_BOUNDS_H > > #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP > -extern bool hugetlb_free_vmemmap_enabled; > +DECLARE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, > + hugetlb_free_vmemmap_enabled_key); > + > +static __always_inline bool hugetlb_free_vmemmap_enabled(void) > +{ > + return static_branch_maybe(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, > + &hugetlb_free_vmemmap_enabled_key); > +} > > /* > * If the feature of freeing some vmemmap pages associated with each HugeTLB > @@ -205,7 +212,7 @@ extern bool hugetlb_free_vmemmap_enabled; > */ > static __always_inline const struct page *page_fixed_fake_head(const struct page *page) > { > - if (!hugetlb_free_vmemmap_enabled) > + if (!hugetlb_free_vmemmap_enabled()) > return page; > > /* > @@ -229,10 +236,15 @@ static __always_inline const struct page *page_fixed_fake_head(const struct page > return page; > } > #else > -static __always_inline const struct page *page_fixed_fake_head(const struct page *page) > +static inline const struct page *page_fixed_fake_head(const struct page *page) > { > return page; > } > + > +static inline bool hugetlb_free_vmemmap_enabled(void) > +{ > + return false; > +} > #endif > > static __always_inline int page_is_fake_head(struct page *page) > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index f4a8fca691ee..22ecb5e21686 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -188,9 +188,9 @@ > #define RESERVE_VMEMMAP_NR 1U > #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) > > -bool hugetlb_free_vmemmap_enabled __read_mostly = > - IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON); > -EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled); > +DEFINE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, > + hugetlb_free_vmemmap_enabled_key); > +EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled_key); > > static int __init early_hugetlb_free_vmemmap_param(char *buf) > { > @@ -204,9 +204,9 @@ static int __init early_hugetlb_free_vmemmap_param(char *buf) > return -EINVAL; > > if (!strcmp(buf, "on")) > - hugetlb_free_vmemmap_enabled = true; > + static_branch_enable(&hugetlb_free_vmemmap_enabled_key); > else if (!strcmp(buf, "off")) > - hugetlb_free_vmemmap_enabled = false; > + static_branch_disable(&hugetlb_free_vmemmap_enabled_key); > else > return -EINVAL; > > @@ -284,7 +284,7 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > BUILD_BUG_ON(__NR_USED_SUBPAGE >= > RESERVE_VMEMMAP_SIZE / sizeof(struct page)); > > - if (!hugetlb_free_vmemmap_enabled) > + if (!hugetlb_free_vmemmap_enabled()) > return; > > vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 4ea91c3ff768..66eaa4e2e76f 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1341,7 +1341,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size) > * populate a single PMD. > */ > return memmap_on_memory && > - !hugetlb_free_vmemmap_enabled && > + !hugetlb_free_vmemmap_enabled() && > IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && > size == memory_block_size_bytes() && > IS_ALIGNED(vmemmap_size, PMD_SIZE) && > -- > 2.11.0 > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A307CC433EF for ; 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charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B38D430000AC X-Stat-Signature: hpk3qgm5i1cmnxxcg7f7gke9eb7mozxp Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=XOUsdZi6; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf03.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.208.41 as permitted sender) smtp.mailfrom=21cnbao@gmail.com X-HE-Tag: 1632687219-45939 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Sep 26, 2021 at 4:15 PM Muchun Song wrote: > > The page_head_if_fake() is used throughout memory management and the > conditional check requires checking a global variable, although the > overhead of this check may be small, it increases when the memory > cache comes under pressure. Also, the global variable will not be > modified after system boot, so it is very appropriate to use static > key machanism. > > Signed-off-by: Muchun Song Reviewed-by: Barry Song > --- > include/linux/hugetlb.h | 6 ------ > include/linux/page-flags.h | 18 +++++++++++++++--- > mm/hugetlb_vmemmap.c | 12 ++++++------ > mm/memory_hotplug.c | 2 +- > 4 files changed, 22 insertions(+), 16 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 3cbf60464398..a90cc88195da 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -1055,12 +1055,6 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr > } > #endif /* CONFIG_HUGETLB_PAGE */ > > -#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP > -extern bool hugetlb_free_vmemmap_enabled; > -#else > -#define hugetlb_free_vmemmap_enabled false > -#endif > - > static inline spinlock_t *huge_pte_lock(struct hstate *h, > struct mm_struct *mm, pte_t *pte) > { > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index b49808e748ce..26e540fd3393 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -185,7 +185,14 @@ enum pageflags { > #ifndef __GENERATING_BOUNDS_H > > #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP > -extern bool hugetlb_free_vmemmap_enabled; > +DECLARE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, > + hugetlb_free_vmemmap_enabled_key); > + > +static __always_inline bool hugetlb_free_vmemmap_enabled(void) > +{ > + return static_branch_maybe(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, > + &hugetlb_free_vmemmap_enabled_key); > +} > > /* > * If the feature of freeing some vmemmap pages associated with each HugeTLB > @@ -205,7 +212,7 @@ extern bool hugetlb_free_vmemmap_enabled; > */ > static __always_inline const struct page *page_fixed_fake_head(const struct page *page) > { > - if (!hugetlb_free_vmemmap_enabled) > + if (!hugetlb_free_vmemmap_enabled()) > return page; > > /* > @@ -229,10 +236,15 @@ static __always_inline const struct page *page_fixed_fake_head(const struct page > return page; > } > #else > -static __always_inline const struct page *page_fixed_fake_head(const struct page *page) > +static inline const struct page *page_fixed_fake_head(const struct page *page) > { > return page; > } > + > +static inline bool hugetlb_free_vmemmap_enabled(void) > +{ > + return false; > +} > #endif > > static __always_inline int page_is_fake_head(struct page *page) > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index f4a8fca691ee..22ecb5e21686 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -188,9 +188,9 @@ > #define RESERVE_VMEMMAP_NR 1U > #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) > > -bool hugetlb_free_vmemmap_enabled __read_mostly = > - IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON); > -EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled); > +DEFINE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, > + hugetlb_free_vmemmap_enabled_key); > +EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled_key); > > static int __init early_hugetlb_free_vmemmap_param(char *buf) > { > @@ -204,9 +204,9 @@ static int __init early_hugetlb_free_vmemmap_param(char *buf) > return -EINVAL; > > if (!strcmp(buf, "on")) > - hugetlb_free_vmemmap_enabled = true; > + static_branch_enable(&hugetlb_free_vmemmap_enabled_key); > else if (!strcmp(buf, "off")) > - hugetlb_free_vmemmap_enabled = false; > + static_branch_disable(&hugetlb_free_vmemmap_enabled_key); > else > return -EINVAL; > > @@ -284,7 +284,7 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > BUILD_BUG_ON(__NR_USED_SUBPAGE >= > RESERVE_VMEMMAP_SIZE / sizeof(struct page)); > > - if (!hugetlb_free_vmemmap_enabled) > + if (!hugetlb_free_vmemmap_enabled()) > return; > > vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 4ea91c3ff768..66eaa4e2e76f 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1341,7 +1341,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size) > * populate a single PMD. > */ > return memmap_on_memory && > - !hugetlb_free_vmemmap_enabled && > + !hugetlb_free_vmemmap_enabled() && > IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && > size == memory_block_size_bytes() && > IS_ALIGNED(vmemmap_size, PMD_SIZE) && > -- > 2.11.0 >