From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 27 Jul 2015 09:31:39 +0200 (CEST) Received: from mail-wi0-f177.google.com ([209.85.212.177]:36472 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27009718AbbG0HbhsxVfo (ORCPT ); Mon, 27 Jul 2015 09:31:37 +0200 Received: by wicgb10 with SMTP id gb10so98920910wic.1 for ; Mon, 27 Jul 2015 00:31:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; bh=/ZVLsJd+e24bYYmDWQ0jv+LUP6pSo6DVfhU0bIJDDyc=; b=YJsYjmUiLALMRx0lipGkUuQhP8G3uzIEDbfHMAGikPnlpEAUFSRZ0ukWaeQugXgZ5F hRubDX4qtLQV+t7sETt0Th7T3wex48v0wi1P3QcM/AHcRaI7aR6LFjNMRHc1eObAPc9l ewiumOrebrvMzrTS5hQOmgkVgY33lf0ojZlc5UfxUKSYdsuyeH4M7jEJtwvADMqk3ET3 PP6BdIfRYQYLCch3fjSadsN4kqyrfsIGxAsCTm8WrEMFh/l7rAn6Dln6TTtY4ckE6lAy dRD6s5pV8s2kJ/1GwV+jzlrg+AjFLunfJjMTJOfhhzLEQ0RqFa4pje0w69tqMncRbooS fBYA== X-Gm-Message-State: ALoCoQlQPcu2iojgk0n4q3JzGKVjKEwF4zQu72bM1ZT0DMI5iX935xoIVHKsQ4Ljptt85afALENJ X-Received: by 10.194.192.166 with SMTP id hh6mr49829401wjc.127.1437982292579; Mon, 27 Jul 2015 00:31:32 -0700 (PDT) Received: from node.shutemov.name (dsl-espbrasgw1-54f9d4-72.dhcp.inet.fi. [84.249.212.72]) by smtp.gmail.com with ESMTPSA id df1sm12042371wib.12.2015.07.27.00.31.30 (version=TLSv1.2 cipher=AES128-GCM-SHA256 bits=128/128); Mon, 27 Jul 2015 00:31:31 -0700 (PDT) Received: by node.shutemov.name (Postfix, from userid 1000) id C236564FA637; Mon, 27 Jul 2015 10:31:29 +0300 (EEST) Date: Mon, 27 Jul 2015 10:31:29 +0300 From: "Kirill A. Shutemov" To: Eric B Munson Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Paul Gortmaker , Chris Metcalf , Guenter Roeck , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org Subject: Re: [PATCH V5 5/7] mm: mmap: Add mmap flag to request VM_LOCKONFAULT Message-ID: <20150727073129.GE11657@node.dhcp.inet.fi> References: <1437773325-8623-1-git-send-email-emunson@akamai.com> <1437773325-8623-6-git-send-email-emunson@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437773325-8623-6-git-send-email-emunson@akamai.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 48426 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: kirill@shutemov.name Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Fri, Jul 24, 2015 at 05:28:43PM -0400, Eric B Munson wrote: > The cost of faulting in all memory to be locked can be very high when > working with large mappings. If only portions of the mapping will be > used this can incur a high penalty for locking. > > Now that we have the new VMA flag for the locked but not present state, > expose it as an mmap option like MAP_LOCKED -> VM_LOCKED. As I mentioned before, I don't think this interface is justified. MAP_LOCKED has known issues[1]. The MAP_LOCKED problem is not necessary affects MAP_LOCKONFAULT, but still. Let's not add new interface unless it's demonstrably useful. [1] http://lkml.kernel.org/g/20150114095019.GC4706@dhcp22.suse.cz -- Kirill A. Shutemov