From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755396AbcDGIrt (ORCPT ); Thu, 7 Apr 2016 04:47:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7563 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751412AbcDGIrq (ORCPT ); Thu, 7 Apr 2016 04:47:46 -0400 From: Vitaly Kuznetsov To: David Rientjes Cc: Andrew Morton , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Corbet , Dan Williams , "Kirill A. Shutemov" , Mel Gorman , David Vrabel , Igor Mammedov , Lennart Poettering Subject: Re: [PATCH 0/2] memory_hotplug: introduce config and command line options to set the default onlining policy In-Reply-To: (David Rientjes's message of "Wed, 6 Apr 2016 15:13:27 -0700 (PDT)") References: <1459950312-25504-1-git-send-email-vkuznets@redhat.com> <20160406115334.82af80e922f8b3eec6336a8b@linux-foundation.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) Date: Thu, 07 Apr 2016 10:47:41 +0200 Message-ID: <87y48phkk2.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Rientjes writes: > On Wed, 6 Apr 2016, Andrew Morton wrote: > >> > This patchset continues the work I started with: >> > >> > commit 31bc3858ea3ebcc3157b3f5f0e624c5962f5a7a6 >> > Author: Vitaly Kuznetsov >> > Date: Tue Mar 15 14:56:48 2016 -0700 >> > >> > memory-hotplug: add automatic onlining policy for the newly added memory >> > >> > Initially I was going to stop there and bring the policy setting logic to >> > userspace. I met two issues on this way: >> > >> > 1) It is possible to have memory hotplugged at boot (e.g. with QEMU). These >> > blocks stay offlined if we turn the onlining policy on by userspace. >> > >> > 2) My attempt to bring this policy setting to systemd failed, systemd >> > maintainers suggest to change the default in kernel or ... to use tmpfiles.d >> > to alter the policy (which looks like a hack to me): >> > https://github.com/systemd/systemd/pull/2938 >> >> That discussion really didn't come to a conclusion and I don't >> understand why you consider Lennert's "recommended way" to be a hack? >> >> > Here I suggest to add a config option to set the default value for the policy >> > and a kernel command line parameter to make the override. >> >> But the patchset looks pretty reasonable regardless of the above. >> > > I don't understand why initscripts simply cannot crawl sysfs memory blocks > and online them for the same behavior. Yes, they can. With this patchset I don't bring any new features, it's rather a convenience so linux distros can make memory hotplug work 'out of the box' without such distro-specific initscripts. Memory hotplug is a standard feature of all major virt technologies so I think it's pretty reasonable to have an option to make it work 'by default' available. -- Vitaly