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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 A9CC2C10F27 for ; Mon, 9 Mar 2020 15:59:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EB1D21D7E for ; Mon, 9 Mar 2020 15:59:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727071AbgCIP7v (ORCPT ); Mon, 9 Mar 2020 11:59:51 -0400 Received: from foss.arm.com ([217.140.110.172]:53974 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726488AbgCIP7v (ORCPT ); Mon, 9 Mar 2020 11:59:51 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4142930E; Mon, 9 Mar 2020 08:59:50 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.71]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B3D203F534; Mon, 9 Mar 2020 08:59:47 -0700 (PDT) Date: Mon, 9 Mar 2020 15:59:45 +0000 From: Catalin Marinas To: Arnd Bergmann Cc: Nishanth Menon , Santosh Shilimkar , Tero Kristo , Linux ARM , Michal Hocko , Rik van Riel , Santosh Shilimkar , Dave Chinner , Russell King - ARM Linux admin , Linux Kernel Mailing List , Linux-MM , Yafang Shao , Al Viro , Johannes Weiner , linux-fsdevel , kernel-team@fb.com, Kishon Vijay Abraham I , Linus Torvalds , Andrew Morton , Roman Gushchin Subject: Re: [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU Message-ID: <20200309155945.GA4124965@arrakis.emea.arm.com> References: <20200211164701.4ac88d9222e23d1e8cc57c51@linux-foundation.org> <20200212085004.GL25745@shell.armlinux.org.uk> <671b05bc-7237-7422-3ece-f1a4a3652c92@oracle.com> <7c4c1459-60d5-24c8-6eb9-da299ead99ea@oracle.com> <20200306203439.peytghdqragjfhdx@kahuna> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 08, 2020 at 11:58:52AM +0100, Arnd Bergmann wrote: > - revisit CONFIG_VMSPLIT_4G_4G for arm32 (and maybe mips32) > to see if it can be done, and what the overhead is. This is probably > more work than the others combined, but also the most promising > as it allows the most user address space and physical ram to be used. A rough outline of such support (and likely to miss some corner cases): 1. Kernel runs with its own ASID and non-global page tables. 2. Trampoline code on exception entry/exit to handle the TTBR0 switching between user and kernel. 3. uaccess routines need to be reworked to pin the user pages in memory (get_user_pages()) and access them via the kernel address space. Point 3 is probably the ugliest and it would introduce a noticeable slowdown in certain syscalls. -- Catalin 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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 29C0CC10F27 for ; Mon, 9 Mar 2020 16:00:10 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EE357208C3 for ; Mon, 9 Mar 2020 16:00:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lebAH2+z" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE357208C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=T8glSjEFjOQUYpaElmpNQC7+ZSbxolyauJbV/3J+HKo=; b=lebAH2+z3Fnsnc +JsSaRg52zpf70LEwSQL3wX4/rOuhtH0/I1jY3mXpXaMlKP4UYm2kR4rRxy04U1M0/X7FkGIuw7EN +6CipyBg7zjW/64ASG+YyBfTFvyoqvuIauQsPYQKf0OkSpel5dHJykEVdrc1ka8jYq0ilFWseLZKu eOQVvVkHFvoVPY29fSZLK5ht9Tuz9E7uWwiF20NW5j4b7BUUdUl8UR48ESTznihnTwVf0FIu54cSs QAlJTstFO/0DeCW8ItDFlxDHjxn3RHh+1QsliGK91fXDhrlZWc0c7OO/Jqi5bGu40KJa3yd0GKMM/ 156tJpY1ry8SEoMB5Kvg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBKp7-0001e0-2k; Mon, 09 Mar 2020 16:00:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBKp0-00011L-En for linux-arm-kernel@lists.infradead.org; Mon, 09 Mar 2020 16:00:04 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4142930E; Mon, 9 Mar 2020 08:59:50 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.71]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B3D203F534; Mon, 9 Mar 2020 08:59:47 -0700 (PDT) Date: Mon, 9 Mar 2020 15:59:45 +0000 From: Catalin Marinas To: Arnd Bergmann Subject: Re: [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU Message-ID: <20200309155945.GA4124965@arrakis.emea.arm.com> References: <20200211164701.4ac88d9222e23d1e8cc57c51@linux-foundation.org> <20200212085004.GL25745@shell.armlinux.org.uk> <671b05bc-7237-7422-3ece-f1a4a3652c92@oracle.com> <7c4c1459-60d5-24c8-6eb9-da299ead99ea@oracle.com> <20200306203439.peytghdqragjfhdx@kahuna> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200309_090002_573129_AD9579B6 X-CRM114-Status: GOOD ( 11.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nishanth Menon , Michal Hocko , Johannes Weiner , Rik van Riel , Roman Gushchin , Santosh Shilimkar , Dave Chinner , Russell King - ARM Linux admin , Linux Kernel Mailing List , Tero Kristo , Linux-MM , Yafang Shao , Al Viro , Santosh Shilimkar , linux-fsdevel , kernel-team@fb.com, Kishon Vijay Abraham I , Linus Torvalds , Andrew Morton , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Mar 08, 2020 at 11:58:52AM +0100, Arnd Bergmann wrote: > - revisit CONFIG_VMSPLIT_4G_4G for arm32 (and maybe mips32) > to see if it can be done, and what the overhead is. This is probably > more work than the others combined, but also the most promising > as it allows the most user address space and physical ram to be used. A rough outline of such support (and likely to miss some corner cases): 1. Kernel runs with its own ASID and non-global page tables. 2. Trampoline code on exception entry/exit to handle the TTBR0 switching between user and kernel. 3. uaccess routines need to be reworked to pin the user pages in memory (get_user_pages()) and access them via the kernel address space. Point 3 is probably the ugliest and it would introduce a noticeable slowdown in certain syscalls. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel