From patchwork Sun Jan 17 15:10:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12025509 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=unavailable 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 55EAFC433E0 for ; Sun, 17 Jan 2021 15:17:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2337D22460 for ; Sun, 17 Jan 2021 15:17:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729652AbhAQPRR (ORCPT ); Sun, 17 Jan 2021 10:17:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729631AbhAQPRA (ORCPT ); Sun, 17 Jan 2021 10:17:00 -0500 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25AE0C061786 for ; Sun, 17 Jan 2021 07:16:20 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id b8so7242947plx.0 for ; Sun, 17 Jan 2021 07:16:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Hon7HPngFu4HxwS2zmocIDkYMNnjiKlEfAxske+w4FE=; b=o9w3kmdeB44NHPerSaJK3r4nOoxS+ilbYyOlCgiDtSEBLu1iCybMnEh6N0HB01ouGy ujK2jPwc+Bu5nlXkTUwdM/9MVD76B4p1sh37oDxRIG6JNF3F8jUnxIBe5/yM930czL2R 6EQihcgC5IdA69gVJdaPHhNIXRxM2wG2t3m12fuqheISvcFpxG4rrmjdHo0y7q9+9+Or 1XPm1uRdWMz6Tdple82oGQK2bYLDVnatibZtQx+djfiYOjhYURytEzion44njw7Js95e Z6CIvMNiJosKbmBjc6VlH1DIwFfYvApHQvsw2dtboWlcN9VoiPm6gleV0SIqRKFCpgQd zDfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Hon7HPngFu4HxwS2zmocIDkYMNnjiKlEfAxske+w4FE=; b=mjtZVGMVz8qz0dpLxa3YrCNV9DDMj7WUrn+//QD5eU+GIXWMIeK3N7KdoeqJYpiC6L FmMRNYIALdEhbWpylcXvJmSrhHdrxUsu9p5VPtV297oavc65A8mEzKm8tZ6ysGJnoUQI ie5aWUNSGFYckNrbbdEI44kGSxSiJfuxiI1G2XUEJrqucuk8wXSoK5Ovg2jvYPj6OSJ7 1KUjZG/w3XlCKLwAWlfcf+mml39DTcyRpLPfjeL9+pV02DSPNCKxa7rASxEMoJhUy91m hxM0VlhRqtUnRn5VzVO56yMHspkB5CwkSftYl6cwaWqsFhgD7W6MzFtdQ2HeCfG9PvDV 8K8g== X-Gm-Message-State: AOAM530dMh9w91veGW0TqM287hbdmefdfrHOpN6TroxgMuJd5HzcTcpW x78GID6X4VC/mh6vsBfIiBNOaA== X-Google-Smtp-Source: ABdhPJyMujlTajhbDBzy36AvKbjYP8NL6BMKYb+gJOmBwUZHEJq3x9AY9vNFVVF5MFrYR3Imq/emHg== X-Received: by 2002:a17:90a:c82:: with SMTP id v2mr21354379pja.171.1610896579767; Sun, 17 Jan 2021 07:16:19 -0800 (PST) Received: from localhost.bytedance.net ([139.177.225.247]) by smtp.gmail.com with ESMTPSA id i22sm9247915pjv.35.2021.01.17.07.15.58 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 17 Jan 2021 07:16:19 -0800 (PST) From: Muchun Song To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com, david@redhat.com, naoya.horiguchi@nec.com Cc: duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Muchun Song Subject: [PATCH v13 12/12] mm: hugetlb: optimize the code with the help of the compiler Date: Sun, 17 Jan 2021 23:10:53 +0800 Message-Id: <20210117151053.24600-13-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210117151053.24600-1-songmuchun@bytedance.com> References: <20210117151053.24600-1-songmuchun@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org We cannot optimize if a "struct page" crosses page boundaries. If it is true, we can optimize the code with the help of a compiler. When free_vmemmap_pages_per_hpage() returns zero, most functions are optimized by the compiler. Signed-off-by: Muchun Song --- include/linux/hugetlb.h | 3 ++- mm/hugetlb_vmemmap.c | 7 +++++++ mm/hugetlb_vmemmap.h | 5 +++-- 3 files changed, 12 insertions(+), 3 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 05fd2db09b78..b685bc4d79d5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -792,7 +792,8 @@ extern bool hugetlb_free_vmemmap_enabled; static inline bool is_hugetlb_free_vmemmap_enabled(void) { - return hugetlb_free_vmemmap_enabled; + return hugetlb_free_vmemmap_enabled && + is_power_of_2(sizeof(struct page)); } #else static inline bool is_hugetlb_free_vmemmap_enabled(void) diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 6b8f7bb2273e..5ea12c7507a6 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -250,6 +250,13 @@ void __init hugetlb_vmemmap_init(struct hstate *h) BUILD_BUG_ON(NR_USED_SUBPAGE >= RESERVE_VMEMMAP_SIZE / sizeof(struct page)); + /* + * The compiler can help us to optimize this function to null + * when the size of the struct page is not power of 2. + */ + if (!is_power_of_2(sizeof(struct page))) + return; + if (!hugetlb_free_vmemmap_enabled) return; diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index 8fd9ae113dbd..e8de41295d4d 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -17,11 +17,12 @@ void hugetlb_vmemmap_init(struct hstate *h); /* * How many vmemmap pages associated with a HugeTLB page that can be freed - * to the buddy allocator. + * to the buddy allocator. The checking of the is_power_of_2() aims to let + * the compiler help us optimize the code as much as possible. */ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { - return h->nr_free_vmemmap_pages; + return is_power_of_2(sizeof(struct page)) ? h->nr_free_vmemmap_pages : 0; } #else static inline void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)