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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no 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 F0AC7C432C0 for ; Sun, 1 Dec 2019 01:51:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A7BA52073C for ; Sun, 1 Dec 2019 01:51:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bKRZdq74" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7BA52073C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 510306B029C; Sat, 30 Nov 2019 20:51:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4C1406B029E; Sat, 30 Nov 2019 20:51:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 387786B029F; Sat, 30 Nov 2019 20:51:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0057.hostedemail.com [216.40.44.57]) by kanga.kvack.org (Postfix) with ESMTP id 216066B029C for ; Sat, 30 Nov 2019 20:51:02 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id C9D7A2C8A for ; Sun, 1 Dec 2019 01:51:01 +0000 (UTC) X-FDA: 76214894322.20.songs61_8f276f79b230 X-HE-Tag: songs61_8f276f79b230 X-Filterd-Recvd-Size: 4331 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Sun, 1 Dec 2019 01:51:01 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 632C6206F0; Sun, 1 Dec 2019 01:51:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575165060; bh=JPgyu+DkpPaPHfSVib9rQetv+Rugns2LUUxAYmLW97Y=; h=Date:From:To:Subject:From; b=bKRZdq74uuaAzF1ihQhx4TQimw7wcqJZT32lcFZTQofyNICAWFPcDsWkIntBE97jU 8OTfSkmiGCxCp9M7zkptZ17BMlQBcgp/ZX3LYL+Xp6VzikwOdtl2ng4DFpieN10Qg3 eNm56TV2ZgbhAePaG/zILclDoXe6MOWMwoFHhXps= Date: Sat, 30 Nov 2019 17:50:59 -0800 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, cai@lca.pw, jglisse@redhat.com, khlebnikov@yandex-team.ru, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, richardw.yang@linux.intel.com, riel@surriel.com, shakeelb@google.com, torvalds@linux-foundation.org Subject: [patch 035/158] mm/rmap.c: reuse mergeable anon_vma as parent when fork Message-ID: <20191201015059.JAkRF-SAj%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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: =46rom: Wei Yang Subject: mm/rmap.c: reuse mergeable anon_vma as parent when fork In __anon_vma_prepare(), we will try to find anon_vma if it is possible to reuse it. While on fork, the logic is different. Since commit 5beb49305251 ("mm: change anon_vma linking to fix multi-process server scalability issue"), function anon_vma_clone() tries to allocate new anon_vma for child process. But the logic here will allocate a new anon_vma for each vma, even in parent this vma is mergeable and share the same anon_vma with its sibling. This may do better for scalability issue, while it is not necessary to do so especially after interval tree is used. Commit 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy") tries to reuse some anon_vma by counting child anon_vma and attached vmas. While for those mergeable anon_vmas, we can just reuse it and not necessary to go through the logic. After this change, kernel build test reduces 20% anon_vma allocation. Do the same kernel build test, it shows run time in sys reduced 11.6%. Origin: real 2m50.467s user 17m52.002s sys 1m51.953s real 2m48.662s user 17m55.464s sys 1m50.553s real 2m51.143s user 17m59.687s sys 1m53.600s Patched: real 2m39.933s user 17m1.835s sys 1m38.802s real 2m39.321s user 17m1.634s sys 1m39.206s real 2m39.575s user 17m1.420s sys 1m38.845s Link: http://lkml.kernel.org/r/20191011072256.16275-2-richardw.yang@linux.i= ntel.com Signed-off-by: Wei Yang Acked-by: Konstantin Khlebnikov Cc: Kirill A. Shutemov Cc: "J=C3=A9r=C3=B4me Glisse" Cc: Mike Kravetz Cc: Rik van Riel Cc: Qian Cai Cc: Shakeel Butt Signed-off-by: Andrew Morton --- mm/rmap.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/mm/rmap.c~mm-rmapc-reuse-mergeable-anon_vma-as-parent-when-fork +++ a/mm/rmap.c @@ -269,6 +269,19 @@ int anon_vma_clone(struct vm_area_struct { struct anon_vma_chain *avc, *pavc; struct anon_vma *root =3D NULL; + struct vm_area_struct *prev =3D dst->vm_prev, *pprev =3D src->vm_prev; + + /* + * If parent share anon_vma with its vm_prev, keep this sharing in in + * child. + * + * 1. Parent has vm_prev, which implies we have vm_prev. + * 2. Parent and its vm_prev have the same anon_vma. + */ + if (!dst->anon_vma && src->anon_vma && + pprev && pprev->anon_vma =3D=3D src->anon_vma) + dst->anon_vma =3D prev->anon_vma; + =20 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { struct anon_vma *anon_vma; _