From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f208.google.com (mail-pd0-f208.google.com [209.85.192.208]) by kanga.kvack.org (Postfix) with ESMTP id 05CF46B0031 for ; Thu, 5 Dec 2013 10:16:15 -0500 (EST) Received: by mail-pd0-f208.google.com with SMTP id r10so248391pdi.3 for ; Thu, 05 Dec 2013 07:16:15 -0800 (PST) Received: from e28smtp09.in.ibm.com (e28smtp09.in.ibm.com. [122.248.162.9]) by mx.google.com with ESMTPS id sb9si378578igb.6.2013.12.04.01.00.23 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 04 Dec 2013 01:00:24 -0800 (PST) Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 4 Dec 2013 14:30:11 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 767E0E0053 for ; Wed, 4 Dec 2013 14:32:22 +0530 (IST) Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id rB4905qH53215272 for ; Wed, 4 Dec 2013 14:30:05 +0530 Received: from d28av03.in.ibm.com (localhost [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id rB4909j7010568 for ; Wed, 4 Dec 2013 14:30:09 +0530 Message-ID: <529EF0FB.2050808@linux.vnet.ibm.com> Date: Wed, 04 Dec 2013 14:38:11 +0530 From: Raghavendra K T MIME-Version: 1.0 Subject: Re: [PATCH RFC] mm readahead: Fix the readahead fail in case of empty numa node References: <1386066977-17368-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20131203143841.11b71e387dc1db3a8ab0974c@linux-foundation.org> <529EE811.5050306@linux.vnet.ibm.com> <20131204004125.a06f7dfc.akpm@linux-foundation.org> In-Reply-To: <20131204004125.a06f7dfc.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Fengguang Wu , David Cohen , Al Viro , Damien Ramonda , linux-mm@kvack.org, linux-kernel@vger.kernel.org On 12/04/2013 02:11 PM, Andrew Morton wrote: > On Wed, 04 Dec 2013 14:00:09 +0530 Raghavendra K T wrote: > >> 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. > Ok. Thanks for the link. I think after that, Here it was changed to pernode: https://lkml.org/lkml/2004/8/21/9 to avoid iteration all over. do you think above patch (+comments) with some sanitized nr (thus avoiding iteration over nodes in remote numa readahead case) does look better? or should we iterate all memory. -- 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