From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx110.postini.com [74.125.245.110]) by kanga.kvack.org (Postfix) with SMTP id 76B646B006C for ; Fri, 28 Sep 2012 07:56:29 -0400 (EDT) Date: Fri, 28 Sep 2012 19:56:23 +0800 From: Fengguang Wu Subject: Re: Re: [PATCH 2/5] mm/readahead: Change the condition for SetPageReadahead Message-ID: <20120928115623.GB1525@localhost> References: <82b88a97e1b86b718fe8e4616820d224f6abbc52.1348309711.git.rprabhu@wnohang.net> <20120922124920.GB17562@localhost> <20120926012900.GA36532@Archie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120926012900.GA36532@Archie> Sender: owner-linux-mm@kvack.org List-ID: To: Raghavendra D Prabhu Cc: linux-mm@kvack.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org On Wed, Sep 26, 2012 at 06:59:00AM +0530, Raghavendra D Prabhu wrote: > Hi, > > > * On Sat, Sep 22, 2012 at 08:49:20PM +0800, Fengguang Wu wrote: > >On Sat, Sep 22, 2012 at 04:03:11PM +0530, raghu.prabhu13@gmail.com wrote: > >>From: Raghavendra D Prabhu > >> > >>If page lookup from radix_tree_lookup is successful and its index page_idx == > >>nr_to_read - lookahead_size, then SetPageReadahead never gets called, so this > >>fixes that. > > > >NAK. Sorry. It's actually an intentional behavior, so that for the > >common cases of many cached files that are accessed frequently, no > >PG_readahead will be set at all to pointlessly trap into the readahead > >routines once and again. > > ACK, thanks for explaining that. However, regarding this, I would > like to know if the implications of the patch > 51daa88ebd8e0d437289f589af29d4b39379ea76 will still apply if > PG_readahead is not set. Would you elaborate the implication and the possible problematic case? Thanks, Fengguang -- 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