From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f176.google.com (mail-pd0-f176.google.com [209.85.192.176]) by kanga.kvack.org (Postfix) with ESMTP id 531D16B0037 for ; Wed, 4 Dec 2013 03:40:31 -0500 (EST) Received: by mail-pd0-f176.google.com with SMTP id w10so21897623pde.35 for ; Wed, 04 Dec 2013 00:40:31 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id eb3si2124564pbc.206.2013.12.04.00.40.29 for ; Wed, 04 Dec 2013 00:40:30 -0800 (PST) Date: Wed, 4 Dec 2013 00:41:25 -0800 From: Andrew Morton Subject: Re: [PATCH RFC] mm readahead: Fix the readahead fail in case of empty numa node Message-Id: <20131204004125.a06f7dfc.akpm@linux-foundation.org> In-Reply-To: <529EE811.5050306@linux.vnet.ibm.com> References: <1386066977-17368-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20131203143841.11b71e387dc1db3a8ab0974c@linux-foundation.org> <529EE811.5050306@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Raghavendra K T Cc: Fengguang Wu , David Cohen , Al Viro , Damien Ramonda , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, 04 Dec 2013 14:00:09 +0530 Raghavendra K T wrote: > > I don't recall the rationale for the current code and of course we > > didn't document it. It might be in the changelogs somewhere - could > > you please do the git digging and see if you can find out? > > Unfaortunately, from my search, I saw that the code belonged to pre git > time, so could not get much information on that. Here: https://lkml.org/lkml/2004/8/20/242 It seems it was done as a rather thoughtless performance optimisation. I'd say it's time to reimplement max_sane_readahead() from scratch. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org