Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757499AbcLBCiw (ORCPT ); Thu, 1 Dec 2016 21:38:52 -0500 Received: from mail-pg0-f48.google.com ([74.125.83.48]:33573 "EHLO mail-pg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756901AbcLBCiu (ORCPT ); Thu, 1 Dec 2016 21:38:50 -0500 Subject: Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support To: Xishi Qiu References: <1480637999-4320-1-git-send-email-scott.branden@broadcom.com> <5840D333.9050801@huawei.com> Cc: Arnd Bergmann , Russell King , Catalin Marinas , Will Deacon , Ard Biesheuvel , Mark Rutland , bielski@fastmail.net, BCM Kernel Feedback , Tang Chen , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Scott Branden Message-ID: <9cfa95ca-a9e9-299d-d020-7e565562dcf5@broadcom.com> Date: Thu, 1 Dec 2016 18:38:46 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <5840D333.9050801@huawei.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2755 Lines: 88 Hi Xishi, Thanks for the reply - please see comments below. On 16-12-01 05:49 PM, Xishi Qiu wrote: > On 2016/12/2 8:19, Scott Branden wrote: > >> This patchset is sent for comment to add memory hotplug support for ARM64 >> based platforms. It follows hotplug code added for other architectures >> in the linux kernel. >> >> I tried testing the memory hotplug feature following documentation from >> Documentation/memory-hotplug.txt. I don't think it is working as expected >> - see below: >> >> To add memory to the system I did the following: >> echo 0x400000000 > /sys/devices/system/memory/probe >> >> The memory is displayed as system ram: >> cat /proc/iomem: >> 74000000-77ffffff : System RAM >> 74080000-748dffff : Kernel code >> 74950000-749d2fff : Kernel data >> 400000000-43fffffff : System RAM >> >> But does not seem to be added to the kernel memory. >> /proc/meminfo did not change. >> >> What else needs to be done so the memory is added to the kernel memory >> pool for normal allocation? >> > > Hi Scott, > > Do you mean it still don't support hod-add after apply this patchset? After applying the patch it appears to partially support hot-add. Please let me know if you think it is working as expected? The memory probe functions in that the memory is registered with the system and shows up in /proc/iomem. But, the memory is not available in /proc/meminfo. Do you think something else needs to be adjusted for ARM64 to hotadd the memory I just found another clue: under /sys/devices/system/memory I only see one memory entry (before or after I try to hotadd additional memory). /sys/devices/system/memory # ls auto_online_blocks memory0 uevent block_size_bytes probe In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 28 and recompile I get the following: /sys/devices/system/memory # ls auto_online_blocks memory7 uevent block_size_bytes probe In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 27 and recompile I get the following: /sys/devices/system/memory # ls auto_online_blocks memory14 uevent block_size_bytes probe If looks to me like something is not working properly in the ARM64 implementation. I should expect to see multiple memoryX entries under /sys/devices/system/memory? > > Thanks, > Xishi Qiu > >> Scott Branden (2): >> arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE, >> MEMORY_PROBE >> arm64: defconfig: enable MEMORY_HOTPLUG config options >> >> arch/arm64/Kconfig | 10 ++++++++++ >> arch/arm64/configs/defconfig | 3 +++ >> arch/arm64/mm/init.c | 42 ++++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 55 insertions(+) >> > > >