Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759531AbaGCSOS (ORCPT ); Thu, 3 Jul 2014 14:14:18 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:40545 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199AbaGCSOQ (ORCPT ); Thu, 3 Jul 2014 14:14:16 -0400 Message-ID: <53B59CB5.9060004@linux.vnet.ibm.com> Date: Thu, 03 Jul 2014 23:41:01 +0530 From: Raghavendra K T Organization: IBM User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Linus Torvalds CC: Andrew Morton , Fengguang Wu , David Cohen , Al Viro , Damien Ramonda , Jan Kara , David Rientjes , Nishanth Aravamudan , linux-mm , Linux Kernel Mailing List Subject: Re: [PATCH] mm readahead: Fix sys_readahead breakage by reverting 2MB limit (bug 79111) References: <1404392547-11648-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14070318-8878-0000-0000-00000D5180F2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/03/2014 09:11 PM, Linus Torvalds wrote: > On Thu, Jul 3, 2014 at 6:02 AM, Raghavendra K T > wrote: >> >> However it broke sys_readahead semantics: 'readahead() blocks until the specified >> data has been read' > > What? Where did you find that insane sentence? And where did you find > an application that depends on that totally insane semantics that sure > as hell was never intentional. > > If this comes from some man-page, Yes it is. then the man-page is just full of > sh*t, and is being crazy. The whole and *only* point of readahead() is > that it does *not* block, and you can do it across multiple files. Entirely agree. Infact I also had the strong opinion that we should rather change man page instead of making Linux performing badly by doing large unnecessary readahead when there is no actual read, and performance numbers have proved that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/