From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 5 Apr 2007 13:07:16 -0700 (PDT) From: Christoph Lameter Subject: Re: [RFC] Free up page->private for compound pages In-Reply-To: Message-ID: References: <20070405033648.GG11192@wotan.suse.de> <20070405035741.GH11192@wotan.suse.de> <20070405042502.GI11192@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: Nick Piggin , linux-mm@kvack.org, dgc@sgi.com List-ID: On Thu, 5 Apr 2007, Hugh Dickins wrote: > > I am not so much worried about performance but more about the availability > > of the page->private field of compound pages. > > Yes, I realise that. I meant > if (unlikely(PageCompound(page)) && PageTail(page)) > shouldn't slow down the !PageCompound fast paths more than the existing > if (unlikely(PageCompound(page))) > or the > if (unlikely(PageTail(page))) > you had. Right. > > I think we cannot overload the page flag after all because of the page > > count issue you pointed out. Guess I should be cleaning up my > > initial patch and repost it? > > I still think PageTail is not worth its own distinct page flag: Well I think we just killed 2 flags for software suspend. Did I not earn at least one by being involved in that project? ;-) > I can understand you drawing back from my page+1 suggestion, > but I don't understand why you're so reluctant to say > if (unlikely(PageCompound(page)) && PageTail(page)) Thats fine with me. Ahh.. This would solve the alias issue.... (Lights going on). Okay we can overload after all. Need to add some comments though. -- 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