From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E540CC433FF for ; Thu, 1 Aug 2019 06:13:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3AC9206A3 for ; Thu, 1 Aug 2019 06:13:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564640029; bh=Jj9wJvJ89lJJZmTX8SZoqNsBI9iuT/BCiqI4U8oMFWk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=RBoOuAFjYUxRyNsw9pHE1feKMqy9ahRFJy/PnyTmLbHo1JQG334N96V/jTd3hZj+P PB+w72xjwP/R43Z82NkW+4QPgGlMk5jZqMztuQEmi307E0/8TxnOMvqIdsCdNqJ8in y+wu1lTdIDEZi0lrUXtHrrJSbNPR+x56rTqIfb4g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729675AbfHAGNs (ORCPT ); Thu, 1 Aug 2019 02:13:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:38558 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726783AbfHAGNs (ORCPT ); Thu, 1 Aug 2019 02:13:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C65CCACEF; Thu, 1 Aug 2019 06:13:46 +0000 (UTC) Date: Thu, 1 Aug 2019 08:13:44 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , Pavel Tatashin , Dan Williams , Oscar Salvador Subject: Re: [PATCH v1] drivers/base/memory.c: Don't store end_section_nr in memory blocks Message-ID: <20190801061344.GA11627@dhcp22.suse.cz> References: <20190731122213.13392-1-david@redhat.com> <20190731124356.GL9330@dhcp22.suse.cz> <20190731132534.GQ9330@dhcp22.suse.cz> <58bd9479-051b-a13b-b6d0-c93aac2ed1b3@redhat.com> <20190731141411.GU9330@dhcp22.suse.cz> <20190731143714.GX9330@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 31-07-19 16:43:58, David Hildenbrand wrote: > On 31.07.19 16:37, Michal Hocko wrote: > > On Wed 31-07-19 16:21:46, David Hildenbrand wrote: > > [...] > >>> Thinking about it some more, I believe that we can reasonably provide > >>> both APIs controlable by a command line parameter for backwards > >>> compatibility. It is the hotplug code to control sysfs APIs. E.g. > >>> create one sysfs entry per add_memory_resource for the new semantic. > >> > >> Yeah, but the real question is: who needs it. I can only think about > >> some DIMM scenarios (some, not all). I would be interested in more use > >> cases. Of course, to provide and maintain two APIs we need a good reason. > > > > Well, my 3TB machine that has 7 movable nodes could really go with less > > than > > $ find /sys/devices/system/memory -name "memory*" | wc -l > > 1729> > > The question is if it would be sufficient to increase the memory block > size even further for these kinds of systems (e.g., via a boot parameter > - I think we have that on uv systems) instead of having blocks of > different sizes. Say, 128GB blocks because you're not going to hotplug > 128MB DIMMs into such a system - at least that's my guess ;) The system has [ 0.000000] ACPI: SRAT: Node 1 PXM 1 [mem 0x10000000000-0x17fffffffff] [ 0.000000] ACPI: SRAT: Node 2 PXM 2 [mem 0x80000000000-0x87fffffffff] [ 0.000000] ACPI: SRAT: Node 3 PXM 3 [mem 0x90000000000-0x97fffffffff] [ 0.000000] ACPI: SRAT: Node 4 PXM 4 [mem 0x100000000000-0x107fffffffff] [ 0.000000] ACPI: SRAT: Node 5 PXM 5 [mem 0x110000000000-0x117fffffffff] [ 0.000000] ACPI: SRAT: Node 6 PXM 6 [mem 0x180000000000-0x183fffffffff] [ 0.000000] ACPI: SRAT: Node 7 PXM 7 [mem 0x190000000000-0x191fffffffff] hotplugable memory. I would love to have those 7 memory blocks to work with. Any smaller grained split is just not helping as the platform will not be able to hotremove it anyway. -- Michal Hocko SUSE Labs