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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BB2AC433FE for ; Wed, 22 Sep 2021 10:27:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74ACB60F44 for ; Wed, 22 Sep 2021 10:27:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234831AbhIVK2p (ORCPT ); Wed, 22 Sep 2021 06:28:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234818AbhIVK2o (ORCPT ); Wed, 22 Sep 2021 06:28:44 -0400 Received: from mail-pg1-x52d.google.com (mail-pg1-x52d.google.com [IPv6:2607:f8b0:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89AB5C061574 for ; Wed, 22 Sep 2021 03:27:14 -0700 (PDT) Received: by mail-pg1-x52d.google.com with SMTP id r2so2156338pgl.10 for ; Wed, 22 Sep 2021 03:27:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=z9Y75SXjQ4OjFnf6AL18GnX+kpqvEJUigzCibLGNWc0=; b=GoaNh0eyBtI0BAqbHw0AIPyMRmRMogyXs6ENtuhJGZRh7QLB6qZhAYmlhRt3JpTkmg w+FjzBOWFidlgTJxxCS1rlaNtWkqw9hU8SIgyItfljjyCa6vLtSpriQ/VDeRt7FHf2Ju P4yVKFidSEWAYw2n4yMjkX8Ry9IX/tvlbBZ2l+/C61KUcldmySBCsVL2S65jZFVPNOKo q5z4V9kz6d12molI4J1Q7OB3ZpjEXV0Sr1JZL5LXOVOikW/niitVMPYeW5l0l6P1KRfl zVG34ggd/XbKZoP34T11Le4LU7XbyNHtnHWUEksOrEJ996dvlTq6gFCEDK8WbtuQbh6+ qqbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=z9Y75SXjQ4OjFnf6AL18GnX+kpqvEJUigzCibLGNWc0=; b=usngAYQtUZg2YYwr+EVYvHbXk+iU9IX5zAWMDRSPBtEwAC9S10hfxnZB1walh0RAcb fNmghnJ3eut5uXD/fIT07bYX3gNIRkAgHMvmH/5PKWdXBC7qIvXz03JC4eQsjGjJtFdY N0o5TfZcWOp5wEYN7r+1jXNugTnKgu3nOroqjVeIC3q/lzzU3DLXJ7wAPE/5amhGKZcy NHrzPMBzeIjYtY8cu9XNIjklJwI+RNWvZouwqv7TsQ/7E6e7+YuUu07MfV8efNwh5nnL ltbBnMxjdJbwBv3AFgxmTrCEHMGgEdim/lYw3kaaOIY2eNtmgnqfByQlhWBuEwWcU25D ww3g== X-Gm-Message-State: AOAM5323JkCnjEiSkzGr/3Prz237U/qB2y0onYiMI2W2nngmMmU7ibVI RurjyjQHOfkVlIZLv6vKpXUxhw== X-Google-Smtp-Source: ABdhPJwj+m8/3Sco/DMCLFXrMXDs8yZjN0k1vj0JTznwjQRew1gI7Jr5pVDALF/DRfwJHuGQAjB39w== X-Received: by 2002:a63:1f24:: with SMTP id f36mr32764347pgf.6.1632306434072; Wed, 22 Sep 2021 03:27:14 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id s89sm1821929pjj.43.2021.09.22.03.27.08 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Sep 2021 03:27:13 -0700 (PDT) From: Muchun Song To: mike.kravetz@oracle.com, akpm@linux-foundation.org, osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com, david@redhat.com, chenhuang5@huawei.com, bodeddub@amazon.com, corbet@lwn.net, willy@infradead.org, 21cnbao@gmail.com Cc: duanxiongchun@bytedance.com, fam.zheng@bytedance.com, smuchun@gmail.com, zhengqi.arch@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song Subject: [PATCH v3 2/4] mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key Date: Wed, 22 Sep 2021 18:24:09 +0800 Message-Id: <20210922102411.34494-3-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210922102411.34494-1-songmuchun@bytedance.com> References: <20210922102411.34494-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org 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 --- include/linux/hugetlb.h | 10 ++++++++-- include/linux/page-flags.h | 6 ++++-- mm/hugetlb_vmemmap.c | 12 ++++++------ mm/memory_hotplug.c | 2 +- 4 files changed, 19 insertions(+), 11 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 1faebe1cd0ed..4cc647a5dbf8 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1066,9 +1066,15 @@ 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; +static inline bool hugetlb_free_vmemmap_enabled(void) +{ + return static_key_enabled(&hugetlb_free_vmemmap_enabled_key); +} #else -#define hugetlb_free_vmemmap_enabled false +static inline bool hugetlb_free_vmemmap_enabled(void) +{ + return false; +} #endif static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index b47a7f51d2c3..54e119e44496 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -185,7 +185,8 @@ 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); /* * If the feature of freeing some vmemmap pages associated with each HugeTLB @@ -205,7 +206,8 @@ 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 (!static_branch_maybe(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, + &hugetlb_free_vmemmap_enabled_key)) return page; /* * Only addresses aligned with PAGE_SIZE of struct page may be fake head diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 527bcaa44a48..47517e878ed5 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 0488eed3327c..89c1fde02162 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