From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f179.google.com (mail-we0-f179.google.com [74.125.82.179]) by kanga.kvack.org (Postfix) with ESMTP id C48016B0031 for ; Tue, 8 Apr 2014 14:51:57 -0400 (EDT) Received: by mail-we0-f179.google.com with SMTP id x48so1431596wes.10 for ; Tue, 08 Apr 2014 11:51:54 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id v8si3989764eew.157.2014.04.08.11.51.53 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 08 Apr 2014 11:51:53 -0700 (PDT) Date: Tue, 8 Apr 2014 19:51:46 +0100 From: Mel Gorman Subject: Re: [RFC PATCH 0/5] Use an alternative to _PAGE_PROTNONE for _PAGE_NUMA v2 Message-ID: <20140408185146.GP7292@suse.de> References: <1396962570-18762-1-git-send-email-mgorman@suse.de> <53440A5D.6050301@zytor.com> <20140408164652.GL7292@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: "H. Peter Anvin" , Linux-X86 , Cyrill Gorcunov , Ingo Molnar , Steven Noonan , Rik van Riel , David Vrabel , Andrew Morton , Peter Zijlstra , Andrea Arcangeli , Dave Hansen , Srikar Dronamraju , Linux-MM , LKML On Tue, Apr 08, 2014 at 10:01:39AM -0700, Linus Torvalds wrote: > On Tue, Apr 8, 2014 at 9:46 AM, Mel Gorman wrote: > > > > If you are ok with leaving _PAGE_NUMA as _PAGE_PROTNONE > > NO I AM NOT! > > Dammit, this feature is f*cking brain-damaged. > > My complaint has been (and continues to be): > > - either it is 100% the same as PROTNONE, in which case thjat > _PAGE_NUMA bit had better go away, and you just use the protnone > helpers! > In which case we'd still use VMAs to distinguish between PROTNONE faults and NUMA hinting faults. We may still need some special casing. It's plan b but not my preferred solution at this time. > - if it's not the same as PROTNONE, then it damn well needs a different bit. > With this series applied _PAGE_NUMA != _PAGE_PROTNONE. > You can't have it both ways. You guys tried. The Xen case shows that > trying to distinguish the two DOES NOT WORK. But even apart from the > Xen case, it was just a confusing hell. > Which is why I responded with a series that used a different bit instead of more discussions that would reach the same conclusion. > Like Yoda said: "Either they are the same or they are not. There is no 'try'". > > So pick one solution. Don't try to pick the mixed-up half-way case > that is a disaster and makes no sense. > I picked a solution. The posted series uses a different bit. -- Mel Gorman SUSE Labs -- 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