From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f178.google.com (mail-yk0-f178.google.com [209.85.160.178]) by kanga.kvack.org (Postfix) with ESMTP id 3FB2F6B0005 for ; Tue, 26 Jan 2016 18:11:38 -0500 (EST) Received: by mail-yk0-f178.google.com with SMTP id u68so91474021ykd.2 for ; Tue, 26 Jan 2016 15:11:38 -0800 (PST) Received: from mail-yk0-x22f.google.com (mail-yk0-x22f.google.com. [2607:f8b0:4002:c07::22f]) by mx.google.com with ESMTPS id v1si1242139ywe.138.2016.01.26.15.11.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Jan 2016 15:11:37 -0800 (PST) Received: by mail-yk0-x22f.google.com with SMTP id v14so220056885ykd.3 for ; Tue, 26 Jan 2016 15:11:37 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20160126145153.44e4f38b04200209d133c0a3@linux-foundation.org> References: <20160126000639.358.89668.stgit@dwillia2-desk3.amr.corp.intel.com> <20160126141152.e1043d14502dcca17813afb3@linux-foundation.org> <20160126145153.44e4f38b04200209d133c0a3@linux-foundation.org> Date: Tue, 26 Jan 2016 15:11:36 -0800 Message-ID: Subject: Re: [RFC PATCH] mm: support CONFIG_ZONE_DEVICE + CONFIG_ZONE_DMA From: Dan Williams Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton 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, Jan 26, 2016 at 2:51 PM, Andrew Morton wrote: > 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? > Will do, especially since other efforts are feeling the pinch on the MAX_NR_ZONES limitation. -- 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