From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f46.google.com (mail-wm0-f46.google.com [74.125.82.46]) by kanga.kvack.org (Postfix) with ESMTP id EA8506B0005 for ; Wed, 27 Jan 2016 08:09:20 -0500 (EST) Received: by mail-wm0-f46.google.com with SMTP id l66so1736557wml.0 for ; Wed, 27 Jan 2016 05:09:20 -0800 (PST) Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com. [195.75.94.111]) by mx.google.com with ESMTPS id w77si11017477wme.5.2016.01.27.05.09.19 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 27 Jan 2016 05:09:20 -0800 (PST) Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 27 Jan 2016 13:09:19 -0000 Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 0C6D01B08067 for ; Wed, 27 Jan 2016 13:09:18 +0000 (GMT) Received: from d06av01.portsmouth.uk.ibm.com (d06av01.portsmouth.uk.ibm.com [9.149.37.212]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0RD9Arf10748214 for ; Wed, 27 Jan 2016 13:09:10 GMT Received: from d06av01.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av01.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0RD99SP014362 for ; Wed, 27 Jan 2016 06:09:09 -0700 Subject: Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting References: <1453799905-10941-1-git-send-email-borntraeger@de.ibm.com> <1453799905-10941-4-git-send-email-borntraeger@de.ibm.com> <20160126181903.GB4671@osiris> <20160127001918.GA7089@js1304-P5Q-DELUXE> <20160127005920.GB7089@js1304-P5Q-DELUXE> <56A8BB15.9070305@suse.cz> <56A8BC6D.9080101@de.ibm.com> <56A8C028.7050305@suse.cz> From: Christian Borntraeger Message-ID: <56A8C175.9030702@de.ibm.com> Date: Wed, 27 Jan 2016 14:09:09 +0100 MIME-Version: 1.0 In-Reply-To: <56A8C028.7050305@suse.cz> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka , Joonsoo Kim , David Rientjes Cc: Heiko Carstens , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org On 01/27/2016 02:03 PM, Vlastimil Babka wrote: > On 01/27/2016 01:47 PM, Christian Borntraeger wrote: >> On 01/27/2016 01:41 PM, Vlastimil Babka wrote: >>> On 01/27/2016 01:59 AM, Joonsoo Kim wrote: >>> >>> I think it might be worth also to convert debug_pagealloc_enabled() to be based >>> on static key, like I did for page_owner [1]. That should help make it possible >>> to have virtually no overhead when compiling kernel with CONFIG_DEBUG_PAGEALLOC >>> without enabling it boot-time. I assume it's one of the goals here? >> >> We could do something like that but dump_stack and setup of the initial identity >> mapping of the kernel as well as the initial page protection are not hot path >> as far as I can tell. Any other places? > > Well, mostly kernel_map_pages() which is used in page allocation hotpaths. Right. So indeed, static_key would be a good thing, but certainly an addon patch. -- 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