From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f177.google.com (mail-pf0-f177.google.com [209.85.192.177]) by kanga.kvack.org (Postfix) with ESMTP id 8F6AC6B0005 for ; Tue, 26 Jan 2016 17:51:55 -0500 (EST) Received: by mail-pf0-f177.google.com with SMTP id x125so674058pfb.0 for ; Tue, 26 Jan 2016 14:51:55 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id w70si4726407pfa.98.2016.01.26.14.51.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Jan 2016 14:51:54 -0800 (PST) Date: Tue, 26 Jan 2016 14:51:53 -0800 From: Andrew Morton Subject: Re: [RFC PATCH] mm: support CONFIG_ZONE_DEVICE + CONFIG_ZONE_DMA Message-Id: <20160126145153.44e4f38b04200209d133c0a3@linux-foundation.org> In-Reply-To: References: <20160126000639.358.89668.stgit@dwillia2-desk3.amr.corp.intel.com> <20160126141152.e1043d14502dcca17813afb3@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: Rik van Riel , linux-nvdimm , Dave Hansen , "linux-kernel@vger.kernel.org" , Christoph Hellwig , Linux MM , Ingo Molnar , Mel Gorman , "H. Peter Anvin" , Jerome Glisse , Sudip Mukherjee On Tue, 26 Jan 2016 14:33:48 -0800 Dan Williams wrote: > >> Towards this end, alias ZONE_DMA and ZONE_DEVICE to work around needing > >> to maintain a unique zone number for ZONE_DEVICE. Record the geometry > >> of ZONE_DMA at init (->init_spanned_pages) and use that information in > >> is_zone_device_page() to differentiate pages allocated via > >> devm_memremap_pages() vs true ZONE_DMA pages. Otherwise, use the > >> simpler definition of is_zone_device_page() when ZONE_DMA is turned off. > >> > >> Note that this also teaches the memory hot remove path that the zone may > >> not have sections for all pfn spans (->zone_dyn_start_pfn). > >> > >> A user visible implication of this change is potentially an unexpectedly > >> high "spanned" value in /proc/zoneinfo for the DMA zone. > > > > Well, all these icky tricks are to avoid increasing ZONES_SHIFT, yes? > > Is it possible to just use ZONES_SHIFT=3? > > Last I tried I hit this warning in mm/memory.c > > #warning Unfortunate NUMA and NUMA Balancing config, growing > page-frame for last_cpupid. Well yes, it may take a bit of work - perhaps salvaging a bit from somewhere else if poss. But that might provide a better overall solution so could you please have a think? -- 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