From patchwork Thu Dec 17 12:13:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 11979713 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=-16.7 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,URIBL_BLOCKED,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 778E0C2BB40 for ; Thu, 17 Dec 2020 12:18:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A30A238EF for ; Thu, 17 Dec 2020 12:18:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728582AbgLQMS1 (ORCPT ); Thu, 17 Dec 2020 07:18:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728573AbgLQMS0 (ORCPT ); Thu, 17 Dec 2020 07:18:26 -0500 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6592C0617A7 for ; Thu, 17 Dec 2020 04:17:45 -0800 (PST) Received: by mail-pf1-x432.google.com with SMTP id q22so18904964pfk.12 for ; Thu, 17 Dec 2020 04:17:45 -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=zLKc/ylYHo2GjStF5CCHYeuxj4GTbCnD5ZdkK0cu8t0=; b=tU0IqBKmVMhKyj8NikbXTGBgiH4IX66VEr+KuEmc56agJmFGIoS8nRvEgWiFkEl+e9 YBV1WexgvQzmd4fe5vXEwSmCKv9BTBhzFhOvrjzuTGPMvlJyChkbB3dyCUR6Hvw04dI2 P8su279ZRwIpSIDybEf+3GhBGemvcfwgfcpArJHAKGhSV6rPG/VCddE2bOsbDS1f5hXq wJjLzhqMWpecu2tjJsgWxMwaxRVxMm422EcTHtDm+TWtmB5viZkTY1Mbup0C8/8oefLl 3cGBiBBMjF1MLZI0m6WkVkkiemo/iv1tBvaBleCfjBxXNTRasnRiRjumo7mVdMrMp9vQ vOfg== 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=zLKc/ylYHo2GjStF5CCHYeuxj4GTbCnD5ZdkK0cu8t0=; b=tJfVKdchNeXBcG7vnAl1K5jTT45UgiLK92tXibtANyjsOaMJxlmFF5xez7H2694mHs Zj6m5KBFXbqrrZ/0qBbIJxTBe+uWOG0FOR/byROijSvwQBz4Tp5tZJ78kHOQGnWEiGyn UFvpoUbiycvtRxb2WCGg7/x427EpRnoQi/cGqtL76zSiFqv7mmuuuJNIJyL1yEDGlUwf a8jA2UxHr9NIuFw17sywOeQoowXjIf9LwPhAaqlHIhZGfv17C1GGA33wG50P5+1bOTEY UElIqPKr0wph/ELKiETG0bRntFaU5Kg6PKN2ydX6CupHTUouqzxonSlBqkdq/+ya8syF cSrg== X-Gm-Message-State: AOAM533a4UDH+VfCcnmNz7oGRG9gbxqzegOrlJ+mH5cycFNYb+FOlzeP umxCMK5Rp3vxwVNgKKkjAFar9Q== X-Google-Smtp-Source: ABdhPJwNWAF94v1/MjPZmdhFmgA8vL4MblAFVKgbyIhGzQw5FgVtgMkV10xLyk+9ehHM6GKpzQ0SgQ== X-Received: by 2002:a62:ae0c:0:b029:1a5:819d:9ac5 with SMTP id q12-20020a62ae0c0000b02901a5819d9ac5mr18177290pff.26.1608207465486; Thu, 17 Dec 2020 04:17:45 -0800 (PST) Received: from localhost.localdomain ([139.177.225.237]) by smtp.gmail.com with ESMTPSA id n15sm2775691pgl.31.2020.12.17.04.17.33 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Dec 2020 04:17:44 -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 v10 11/11] mm/hugetlb: Optimize the code with the help of the compiler Date: Thu, 17 Dec 2020 20:13:03 +0800 Message-Id: <20201217121303.13386-12-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20201217121303.13386-1-songmuchun@bytedance.com> References: <20201217121303.13386-1-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 7295f6b3d55e..adc17765e0e9 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -791,7 +791,8 @@ 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 ad123b760245..987248a004f0 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -242,6 +242,13 @@ 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)