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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 34107C433ED for ; Mon, 19 Apr 2021 09:15:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BBBD46113C for ; Mon, 19 Apr 2021 09:15:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBBD46113C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4D6656B0036; Mon, 19 Apr 2021 05:15:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4862A6B006E; Mon, 19 Apr 2021 05:15:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B1AE6B0070; Mon, 19 Apr 2021 05:15:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0170.hostedemail.com [216.40.44.170]) by kanga.kvack.org (Postfix) with ESMTP id 1007A6B0036 for ; Mon, 19 Apr 2021 05:15:10 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id B416B181AEF32 for ; Mon, 19 Apr 2021 09:15:09 +0000 (UTC) X-FDA: 78048557538.27.6555E86 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf09.hostedemail.com (Postfix) with ESMTP id E82506000113 for ; Mon, 19 Apr 2021 09:15:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618823708; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JJHH0NX3OsQ2e3bz8MbvbRBxnLsHKmu/POOlzwxl9eU=; b=QX2G3CzJ/NKD5UOg85qHAZTkn4RiYHvYTExtbc+L2jA7dhUw0gVsiT0k5iKqRzYhEVDons pF1+55fvvZBvw9Gn3JVIcieUx0XziS9/K+8s9SJ1s9J0VSkh8kwTvP28dW+dEFJcvlIqU0 KMPI/jgfhyYGNVdLCq+Z1xq5xuU5A5w= Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-240-mwqyge9FNjyEl4-7dk93YA-1; Mon, 19 Apr 2021 05:15:06 -0400 X-MC-Unique: mwqyge9FNjyEl4-7dk93YA-1 Received: by mail-ej1-f69.google.com with SMTP id d11-20020a170906370bb029037c87968c04so3416854ejc.17 for ; Mon, 19 Apr 2021 02:15:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:organization:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=JJHH0NX3OsQ2e3bz8MbvbRBxnLsHKmu/POOlzwxl9eU=; b=ADOPUatpzA3dYntulzEn7Raigev2jR6DSjNu44ihn0AQkDzVrBPp/nljh4Gq03Jtbp nlx9Jrgaa1tIKBM4iH/haF0/sSJ0uG6NkqgCNLDD1dMs96qQzLxLmlGYC56YEoT8+jqu TDyEvwaueUMC9k1bjU0jwlMVUexd6BxxYSmh8qvS4Bx7upllhT+eismkmmYMSQGOU7Rv qDLBL6Gwj5ixBdahtNx79h49Ua5cUmkpjQfyONjAFOXzeJ5zPGADHOXmHhdwFTETr6SQ xWFCFHOBWhDqCBm2HWX+IjyRACjUfgUi4q8NkVsd8VUtLmCOeXwyJ+fp2Xd++f8USHrp FFOQ== X-Gm-Message-State: AOAM532BxDgZjchHLVolvCszr0GcmZPnK33JE6jX4mePGY9eqd/snEJU t6Mp3LABn+gQ1cNXAecYp0G24aiGqC5h4WVCnkPvCjJjta9Z0iSuxL0M3INoGBXrpKAxm98IGKn ZLcaUqcGeyqE= X-Received: by 2002:a05:6402:42d1:: with SMTP id i17mr23711291edc.131.1618823705529; Mon, 19 Apr 2021 02:15:05 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxYzYlDX/eTm99p4Oo7Oz5LAmRLoDDSSTEdvjwkyJC6GdKrJUD2OsxJ6l4DnJdCX72CgXH3hg== X-Received: by 2002:a05:6402:42d1:: with SMTP id i17mr23711232edc.131.1618823705193; Mon, 19 Apr 2021 02:15:05 -0700 (PDT) Received: from [192.168.3.132] (p5b0c69b8.dip0.t-ipconnect.de. [91.12.105.184]) by smtp.gmail.com with ESMTPSA id y16sm12144407edc.62.2021.04.19.02.15.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Apr 2021 02:15:04 -0700 (PDT) To: Mike Rapoport , Andrew Morton Cc: Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Matthew Garrett , Mark Rutland , Michal Hocko , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , "Rafael J. Wysocki" , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , Yury Norov , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, kernel test robot References: <20210419084218.7466-1-rppt@kernel.org> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] secretmem: optimize page_is_secretmem() Message-ID: <3b30ac54-8a92-5f54-28f0-f110a40700c7@redhat.com> Date: Mon, 19 Apr 2021 11:15:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210419084218.7466-1-rppt@kernel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Stat-Signature: qcxehejartr4yndk5n7g74wqo9obxkma X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E82506000113 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=170.10.133.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618823704-740645 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: On 19.04.21 10:42, Mike Rapoport wrote: > From: Mike Rapoport >=20 > Kernel test robot reported -4.2% regression of will-it-scale.per_thread= _ops > due to commit "mm: introduce memfd_secret system call to create "secret= " > memory areas". >=20 > The perf profile of the test indicated that the regression is caused by > page_is_secretmem() called from gup_pte_range() (inlined by gup_pgd_ran= ge): >=20 > 27.76 +2.5 30.23 perf-profile.children.cycles-pp.gup_pgd_rang= e > 0.00 +3.2 3.19 =C2=B1 2% perf-profile.children.cycles-pp.page_ma= pping > 0.00 +3.7 3.66 =C2=B1 2% perf-profile.children.cycles-pp.page_is= _secretmem >=20 > Further analysis showed that the slow down happens because neither > page_is_secretmem() nor page_mapping() are not inline and moreover, > multiple page flags checks in page_mapping() involve calling > compound_head() several times for the same page. >=20 > Make page_is_secretmem() inline and replace page_mapping() with page fl= ag > checks that do not imply page-to-head conversion. >=20 > Reported-by: kernel test robot > Signed-off-by: Mike Rapoport > --- >=20 > @Andrew, > The patch is vs v5.12-rc7-mmots-2021-04-15-16-28, I'd appreciate if it = would > be added as a fixup to the memfd_secret series. >=20 > include/linux/secretmem.h | 26 +++++++++++++++++++++++++- > mm/secretmem.c | 12 +----------- > 2 files changed, 26 insertions(+), 12 deletions(-) >=20 > diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h > index 907a6734059c..b842b38cbeb1 100644 > --- a/include/linux/secretmem.h > +++ b/include/linux/secretmem.h > @@ -4,8 +4,32 @@ > =20 > #ifdef CONFIG_SECRETMEM > =20 > +extern const struct address_space_operations secretmem_aops; > + > +static inline bool page_is_secretmem(struct page *page) > +{ > + struct address_space *mapping; > + > + /* > + * Using page_mapping() is quite slow because of the actual call > + * instruction and repeated compound_head(page) inside the > + * page_mapping() function. > + * We know that secretmem pages are not compound and LRU so we can > + * save a couple of cycles here. > + */ > + if (PageCompound(page) || !PageLRU(page)) > + return false; I'd assume secretmem pages are rare in basically every setup out there.=20 So maybe throwing in a couple of likely()/unlikely() might make sense. > + > + mapping =3D (struct address_space *) > + ((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS); > + Not sure if open-coding page_mapping is really a good idea here -- or=20 even necessary after the fast path above is in place. Anyhow, just my 2=20 cents. The idea of the patch makes sense to me. --=20 Thanks, David / dhildenb