From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Rientjes via Linuxppc-dev Subject: (unknown) Date: Wed, 3 Feb 2016 08:52:46 +1100 (AEDT) Message-ID: References: <1453889401-43496-1-git-send-email-borntraeger@de.ibm.com> <1453889401-43496-3-git-send-email-borntraeger@de.ibm.com> <56A9E3D1.3090001@de.ibm.com> Reply-To: David Rientjes Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7384601280624994056==" Return-path: In-Reply-To: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: List-Help: Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Archive: List-Post: To: Christian Borntraeger Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, davej@codemonkey.org.uk, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim , akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net List-ID: --===============7384601280624994056== Content-Type: message/rfc822 Content-Disposition: inline Return-Path: X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from mail-pf0-x236.google.com (mail-pf0-x236.google.com [IPv6:2607:f8b0:400e:c00::236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id D87CF1A0204 for ; Wed, 3 Feb 2016 08:51:39 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b=aD1uBLau; dkim-atps=neutral Received: by mail-pf0-x236.google.com with SMTP id w123so1092865pfb.0 for ; Tue, 02 Feb 2016 13:51:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version:content-type; bh=TMWMuLKyzFjVKjQSgHVUsYZgrlplQT3uS4flE+ygaPc=; b=aD1uBLauawXUiBi2he0qc8KnyGTs8u4u37Cu6F6Rl5Oq10qCWGr0kyfOJKQB1a8VAe eKOPPnwDuFe7JDN0OCz07oqQaMGR1sN6SDTBFEgUymC17vV+oMOmUdS31JJ2qMi/KNfU 4K7EmK3GwWWw91yx1QnUAPK9TcswDYuTc33Lm1ejLxvToMzi5vkUT0YqEkR/95yUNcbc DbyxDhaxB0Gtcq1LCKFhI19zzIOnfuN/vXPdvF4QvdNAJfRLNqrvcQIvEdeEbtDXv/Hz X6i2tuCQ5IJQOh2dTXwA0i82981c5wYxyRFYq1ravuxIBZB5VwHck/0BLlvNzqbJKcIR kNbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; bh=TMWMuLKyzFjVKjQSgHVUsYZgrlplQT3uS4flE+ygaPc=; b=VmI7Ms17YN631rQJ5xmb0HRl9qvk7mV8nsm9MyWKjp8lfuNmdfMcGURE0lNUMWXH8S m6p29NKZ8Bmdxw+Zplm0poU6GrrC0QHToHLxZJB5MMv5wVwMumQ4bt4BVFITLEJhGR54 yI+8t0tJHRLTW/70/X7wiwPtNgsqIm1Y45Nmj0HX9yMxc6h6ZOvkx7lcaaeUVzJc3Qw4 NGwcQgDCG7sThiSuYurTMhjPTFcCRvrLOFyGB7tOd0FuHgMNJBKAxNjHWj/8AknjEvA6 vgtxaf172PvBTuX3nmURVTV6/XptTLTbwws/g64gfuiGti8d3+9ewHUhvTaA0dCohcUE 3bVQ== X-Gm-Message-State: AG10YOQHWLxlPp5DPEiVbdnaTfG5Aa+oF126n7ucspKBGGyINH75fafLDDKT2islq/MM6ls7 X-Received: by 10.98.8.14 with SMTP id c14mr50487655pfd.42.1454449896347; Tue, 02 Feb 2016 13:51:36 -0800 (PST) Received: from [2620:0:1008:1200:845f:fa21:c55:89c2] ([2620:0:1008:1200:845f:fa21:c55:89c2]) by smtp.gmail.com with ESMTPSA id 72sm4853028pfk.28.2016.02.02.13.51.35 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 02 Feb 2016 13:51:35 -0800 (PST) Date: Tue, 2 Feb 2016 13:51:34 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Christian Borntraeger cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net, Joonsoo Kim , davej@codemonkey.org.uk Subject: Re: [PATCH v3 2/3] x86: query dynamic DEBUG_PAGEALLOC setting In-Reply-To: Message-ID: References: <1453889401-43496-1-git-send-email-borntraeger@de.ibm.com> <1453889401-43496-3-git-send-email-borntraeger@de.ibm.com> <56A9E3D1.3090001@de.ibm.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII On Thu, 28 Jan 2016, David Rientjes wrote: > On Thu, 28 Jan 2016, Christian Borntraeger wrote: > > > Indeed, I only touched the identity mapping and dump stack. > > The question is do we really want to change free_init_pages as well? > > The unmapping during runtime causes significant overhead, but the > > unmapping after init imposes almost no runtime overhead. Of course, > > things get fishy now as what is enabled and what not. > > > > Kconfig after my patch "mm/debug_pagealloc: Ask users for default setting of debug_pagealloc" > > (in mm) now states > > ----snip---- > > By default this option will have a small overhead, e.g. by not > > allowing the kernel mapping to be backed by large pages on some > > architectures. Even bigger overhead comes when the debugging is > > enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc > > command line parameter. > > ----snip---- > > > > So I am tempted to NOT change free_init_pages, but the x86 maintainers > > can certainly decide differently. Ingo, Thomas, H. Peter, please advise. > > > > I'm sorry, but I thought the discussion of the previous version of the > patchset led to deciding that all CONFIG_DEBUG_PAGEALLOC behavior would be > controlled by being enabled on the commandline and checked with > debug_pagealloc_enabled(). > > I don't think we should have a CONFIG_DEBUG_PAGEALLOC that does some stuff > and then a commandline parameter or CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT > to enable more stuff. It should either be all enabled by the commandline > (or config option) or split into a separate entity. > CONFIG_DEBUG_PAGEALLOC_LIGHT and CONFIG_DEBUG_PAGEALLOC would be fine, but > the current state is very confusing about what is being done and what > isn't. > Ping? --===============7384601280624994056== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KTGludXhwcGMt ZGV2IG1haWxpbmcgbGlzdApMaW51eHBwYy1kZXZAbGlzdHMub3psYWJzLm9yZwpodHRwczovL2xp c3RzLm96bGFicy5vcmcvbGlzdGluZm8vbGludXhwcGMtZGV2 --===============7384601280624994056==--