From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e36.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id l2FNFngV012977 for ; Thu, 15 Mar 2007 19:15:49 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l2FNFnp0062772 for ; Thu, 15 Mar 2007 17:15:49 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l2FNFmWY031936 for ; Thu, 15 Mar 2007 17:15:48 -0600 Subject: Re: [PATCH] mm/filemap.c: unconditionally call mark_page_accessed From: Dave Kleikamp In-Reply-To: <20070315225928.GF6687@v2.random> References: <20070312143900.GB6016@wotan.suse.de> <20070312151355.GB23532@duck.suse.cz> <20070312173500.GF23532@duck.suse.cz> <20070313185554.GA5105@duck.suse.cz> <45F96CCB.4000709@redhat.com> <20070315162944.GI8321@wotan.suse.de> <20070315225928.GF6687@v2.random> Content-Type: text/plain Date: Thu, 15 Mar 2007 18:15:45 -0500 Message-Id: <1174000545.14380.22.camel@kleikamp.austin.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Hugh Dickins , Nick Piggin , Chuck Ebbert , Ashif Harji , Miquel van Smoorenburg , linux-mm@kvack.org, Jan Kara , linux-kernel@vger.kernel.org, akpm@linux-foundation.org List-ID: On Thu, 2007-03-15 at 23:59 +0100, Andrea Arcangeli wrote: > On Thu, Mar 15, 2007 at 05:44:01PM +0000, Hugh Dickins wrote: > > who removed the !offset condition, he should be consulted on its > > reintroduction. > > the !offset check looks a pretty broken heuristic indeed, it would > break random I/O. I wouldn't call it broken. At worst, I'd say it's imperfect. But that's the nature of a heuristic. It most likely works in a huge majority of cases. > The real fix is to add a ra.prev_offset along with > ra.prev_page, and if who implements it wants to be stylish he can as > well use a ra.last_contiguous_read structure that has a page and > offset fields (and then of course remove ra.prev_page). I suggested something along these lines, but I wonder if it's overkill. The !offset check is simple and appears to be a decent improvement over the current code. -- David Kleikamp IBM Linux Technology Center -- 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