From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 25 Apr 2007 08:56:12 -0700 (PDT) From: Christoph Lameter Subject: Re: [RFC 10/16] Variable Order Page Cache: Readahead fixups In-Reply-To: <20070425113613.GF19942@skynet.ie> Message-ID: References: <20070423064845.5458.2190.sendpatchset@schroedinger.engr.sgi.com> <20070423064937.5458.59638.sendpatchset@schroedinger.engr.sgi.com> <20070425113613.GF19942@skynet.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: linux-mm@kvack.org, William Lee Irwin III , Badari Pulavarty , David Chinner , Jens Axboe , Adam Litke , Dave Hansen , Avi Kivity List-ID: On Wed, 25 Apr 2007, Mel Gorman wrote: > > + /* > > + * FIXME: Note the 2M constant here that may prove to > > + * be a problem if page sizes become bigger than one megabyte. > > + */ > > + unsigned long this_chunk = page_cache_index(mapping, 2 * 1024 * 1024); > > > > Should readahead just be disabled when the compound page size is as > large or larger than what readahead normally reads? I am not sure how to solve that one yet. With the above fix we stay at the 2M sized readahead. As the compound order increases so the number of pages is reduced. We could keep the number of pages constant but then very high orders may cause a excessive use of memory for readahead. -- 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