From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [patch 8/8] Pageflags: Eliminate PG_xxx aliases Date: Fri, 7 Mar 2008 13:20:16 +1100 References: <20080305223815.574326323@sgi.com> <200803071148.09759.nickpiggin@yahoo.com.au> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200803071320.16967.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andrew Morton , ak@suse.de, Mel Gorman , apw@shadowen.org, KAMEZAWA Hiroyuki , KOSAKI Motohiro , Rik van Riel , linux-mm@kvack.org List-ID: On Friday 07 March 2008 12:38, Christoph Lameter wrote: > On Fri, 7 Mar 2008, Nick Piggin wrote: > > On Friday 07 March 2008 09:51, Christoph Lameter wrote: > > > On Thu, 6 Mar 2008, Nick Piggin wrote: > > > > > PG_mappedtodisk, /* Has blocks allocated on-disk */ > > > > > PG_reclaim, /* To be reclaimed asap */ > > > > > - /* PG_readahead is only used for file reads; PG_reclaim is only > > > > > for writes */ - PG_readahead = PG_reclaim, /* Reminder to do async > > > > > read-ahead */ PG_buddy, /* Page is free, on buddy lists */ > > > > > > > > IMO it's nice to see these alias up front. > > > > > > I could add a comment pointing to the aliases for those that are > > > aliases? > > > > Yeah that would be better than nothing. I didn't quite > > understand why you made this change in the first place > > though. > > It avoids us having to deal with aliases in the future. It doesn't. You still have to deal with them. > PG_xx at this > point is not unique which can be confusing. See the PG_reclaim in > mm/page_alloc.c. It also means PG_readahead. If I look for > handling of PG_readahead then I wont find it. You can't just pretend not to deal with aliases at that point in mm/page_alloc.c just becuase you only have one name for the bit position. You still have to know that checking for PG_reclaim in bad_page can only be done if it is *also* a bug for PG_readahead to be found set at that point too. Because it is an alias. -- 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