From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx160.postini.com [74.125.245.160]) by kanga.kvack.org (Postfix) with SMTP id 71A506B002B for ; Tue, 16 Oct 2012 23:13:25 -0400 (EDT) Date: Wed, 17 Oct 2012 11:13:16 +0800 From: Fengguang Wu Subject: Re: Re: [PATCH 4/5] Move the check for ra_pages after VM_SequentialReadHint() Message-ID: <20121017031316.GE13769@localhost> References: <20120922124250.GB15962@localhost> <20121016181521.GD2826@Archie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121016181521.GD2826@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 Tue, Oct 16, 2012 at 11:45:21PM +0530, Raghavendra D Prabhu wrote: > Hi, > > > * On Sat, Sep 22, 2012 at 08:42:50PM +0800, Fengguang Wu wrote: > >it.rprabhu@wnohang.net> > >User-Agent: Mutt/1.5.21 (2010-09-15) > >X-Date: Sat Sep 22 18:12:50 IST 2012 > > > >On Sat, Sep 22, 2012 at 04:03:13PM +0530, raghu.prabhu13@gmail.com wrote: > >>From: Raghavendra D Prabhu > >> > >>page_cache_sync_readahead checks for ra->ra_pages again, so moving the check > >>after VM_SequentialReadHint. > > > >Well it depends on what case you are optimizing for. I suspect there > >are much more tmpfs users than VM_SequentialReadHint users. So this > >change is actually not desirable wrt the more widely used cases. > > shm/tmpfs doesn't use this function for fault. They have shmem_fault > for that. So, that shouldn't matter here. Agree? That's true for the regular tmpfs and it still calls filemap_fault() in the !CONFIG_SHMEM case and squashfs/cramfs etc. They together should still overweight the VM_SequentialReadHint users? 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