From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752207Ab3BOWed (ORCPT ); Fri, 15 Feb 2013 17:34:33 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:49167 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751828Ab3BOWeb (ORCPT ); Fri, 15 Feb 2013 17:34:31 -0500 Date: Fri, 15 Feb 2013 14:34:30 -0800 From: Andrew Morton To: Johannes Weiner Cc: Rusty Russell , LKML , Nick Piggin , Stewart Smith , linux-mm@kvack.org, linux-arch@vger.kernel.org Subject: Re: [patch 1/2] mm: fincore() Message-Id: <20130215143430.958b78ab.akpm@linux-foundation.org> In-Reply-To: <20130215222803.GA23930@cmpxchg.org> References: <87a9rbh7b4.fsf@rustcorp.com.au> <20130211162701.GB13218@cmpxchg.org> <20130211141239.f4decf03.akpm@linux-foundation.org> <20130215063450.GA24047@cmpxchg.org> <20130215131451.138e83ce.akpm@linux-foundation.org> <20130215222803.GA23930@cmpxchg.org> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 15 Feb 2013 17:28:03 -0500 Johannes Weiner wrote: > > Yes, and there will be immediate calmour to add more goodies to the > > other seven bits. PageDirty, referenced state, etc. We should think > > about this now, at the design stage rather than grafting things on > > later. > > I'm interested in your "etc.". PG_error, PG_active, PG_writeback, > page huge? Gawd knows. How many crazy people are there out there? If we adopt my use-runlength-encoding suggestion then things get easier. We add an extra arg to the syscall which selects which particular per-page boolean we're looking for and can gather up to 4 billion different PageFoo()s.