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=-9.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 D4CD6C3A5A6 for ; Thu, 29 Aug 2019 13:51:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 73DE72189D for ; Thu, 29 Aug 2019 13:51:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="a3zJNkLb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 73DE72189D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C3DFA6B0003; Thu, 29 Aug 2019 09:51:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BC7316B0006; Thu, 29 Aug 2019 09:51:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A8E936B000C; Thu, 29 Aug 2019 09:51:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0192.hostedemail.com [216.40.44.192]) by kanga.kvack.org (Postfix) with ESMTP id 81CAE6B0003 for ; Thu, 29 Aug 2019 09:51:24 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 1BCD9181AC9B4 for ; Thu, 29 Aug 2019 13:51:24 +0000 (UTC) X-FDA: 75875602488.30.pin68_637ae0fd32f3e X-HE-Tag: pin68_637ae0fd32f3e X-Filterd-Recvd-Size: 4486 Received: from mail-pl1-f194.google.com (mail-pl1-f194.google.com [209.85.214.194]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Thu, 29 Aug 2019 13:51:23 +0000 (UTC) Received: by mail-pl1-f194.google.com with SMTP id 4so1601056pld.10 for ; Thu, 29 Aug 2019 06:51:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=fW3k8zWPWk6FVp5QrWdqwjUBdQ4RebiwFEy2lJKDFrw=; b=a3zJNkLb0Tq4GidOYWeFBl+BOSSAnzsk8SKjd1/mq6SDr0Bi28W3HnkIm7ZP9qZERZ PJDjnROIewGZ3HWRr68Q1bMrWF9HikksxywFuLri5Tt+xcCyRIdaZ8zAbPZwkEVkKEtS kWNhJojo3SH32dQLAgUzUmTnM9Eulr+lV2PhDaRxaw/cGI0UA5y9T814yEIPvANy0QQB jqM5SzZpgwH0S5XYSM8e+ZL+7ev1Ygu7DQwiVvH/1+t+mYLqBz65cXFC0mj1t/q1Zh5w sdhSGQZdbP3ua0iAYc4Tu2tbuKEbbGDceYIZrmkubnB68pTXo9ZHMIc8NJGpepjA/lmk PUtg== 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; bh=fW3k8zWPWk6FVp5QrWdqwjUBdQ4RebiwFEy2lJKDFrw=; b=POBJLDZYpa9PXf3A0cZCtaikFhoX8aqLvyixYwLPp/xz00Jq3Y1JfYJi7OSDvgurCE uaXlqJDZuIWPQ+U2MN80Y0XaSy2h3AZDWbkqGZNjHCZim4RNG+LE35dorjJEOagTrS3d pe+uDoz8wi9fHBt+Z22DujcKRFi4mNkBgspXnsVJJ8Ydi0vRQ5716DPv9Ktg+SojVmD8 cjfBmz+q5Sj4nmyABugQXrQbx2TmaAEJ2T5QVO/m3GDSJGOvHzPtXCiHmAaQOL0TlcO8 ms7sVFo8VCr6sBpdZURoL3yU993V4HqcCYtfE7K+O3A+uqR6RJNqxoC3TNaRdMJWErZw SGEQ== X-Gm-Message-State: APjAAAXY8ezbe00guzRcTXs0W3gS7yzG58Nnbmd/uZBSpyq54dh5CTSw pjoHotWAryHeQP1mA2LhBfw= X-Google-Smtp-Source: APXvYqxtmbM6WXnKoiaNk54ZgSjFsVFn9WynUjYzmF6o52O3dElyrmgEaX2U+RxbfprFvvaJ3DRfdA== X-Received: by 2002:a17:902:fe0e:: with SMTP id g14mr4519162plj.307.1567086682624; Thu, 29 Aug 2019 06:51:22 -0700 (PDT) Received: from VM_12_95_centos.localdomain ([58.87.109.34]) by smtp.googlemail.com with ESMTPSA id w6sm2950630pgg.2.2019.08.29.06.51.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Aug 2019 06:51:21 -0700 (PDT) From: Zhigang Lu To: luzhigang001@gmail.com, mike.kravetz@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Zhigang Lu Subject: [PATCH v2] mm/hugetlb: avoid looping to the same hugepage if !pages and !vmas Date: Thu, 29 Aug 2019 21:50:57 +0800 Message-Id: <1567086657-22528-1-git-send-email-totty.lu@gmail.com> X-Mailer: git-send-email 1.8.3.1 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: From: Zhigang Lu When mmapping an existing hugetlbfs file with MAP_POPULATE, we find it is very time consuming. For example, mmapping a 128GB file takes about 50 milliseconds. Sampling with perfevent shows it spends 99% time in the same_page loop in follow_hugetlb_page(). samples: 205 of event 'cycles', Event count (approx.): 136686374 - 99.04% test_mmap_huget [kernel.kallsyms] [k] follow_hugetlb_page follow_hugetlb_page __get_user_pages __mlock_vma_pages_range __mm_populate vm_mmap_pgoff sys_mmap_pgoff sys_mmap system_call_fastpath __mmap64 follow_hugetlb_page() is called with pages=NULL and vmas=NULL, so for each hugepage, we run into the same_page loop for pages_per_huge_page() times, but doing nothing. With this change, it takes less then 1 millisecond to mmap a 128GB file in hugetlbfs. Signed-off-by: Zhigang Lu Reviewed-by: Haozhong Zhang Reviewed-by: Zongming Zhang Acked-by: Matthew Wilcox --- mm/hugetlb.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6d7296d..2df941a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4391,6 +4391,17 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, break; } } + + if (!pages && !vmas && !pfn_offset && + (vaddr + huge_page_size(h) < vma->vm_end) && + (remainder >= pages_per_huge_page(h))) { + vaddr += huge_page_size(h); + remainder -= pages_per_huge_page(h); + i += pages_per_huge_page(h); + spin_unlock(ptl); + continue; + } + same_page: if (pages) { pages[i] = mem_map_offset(page, pfn_offset); -- 1.8.3.1