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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 C95CAC433E0 for ; Tue, 12 Jan 2021 13:32:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7472320771 for ; Tue, 12 Jan 2021 13:32:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730082AbhALNcB (ORCPT ); Tue, 12 Jan 2021 08:32:01 -0500 Received: from mx2.suse.de ([195.135.220.15]:60566 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730028AbhALNb6 (ORCPT ); Tue, 12 Jan 2021 08:31:58 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 727A7ACB0; Tue, 12 Jan 2021 13:31:16 +0000 (UTC) Date: Tue, 12 Jan 2021 14:31:14 +0100 From: Oscar Salvador To: David Hildenbrand Cc: akpm@linux-foundation.org, mhocko@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, vbabka@suse.cz, pasha.tatashin@soleen.com Subject: Re: [PATCH 4/5] powerpc/memhotplug: Enable MHP_MEMMAP_ON_MEMORY when supported Message-ID: <20210112133108.GA15667@linux> References: <20201217130758.11565-1-osalvador@suse.de> <20201217130758.11565-5-osalvador@suse.de> 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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 11, 2021 at 05:55:37PM +0100, David Hildenbrand wrote: > On 17.12.20 14:07, Oscar Salvador wrote: > With 16MB LMBs it's quite wasteful - you won't even have a huge page > fitting the the remaining part. > > I do wonder if we want this on powerpc only with a bigger LMB/memory > block size (e.g., 256 MB, which is AFAIK the maximum usually found). Yeah, powerpc is trickier than the others. It is more difficult to take advante of this in this platfowm as depending on the page's size, a larger memory are might have been mapped before, and so, further hot-add operations will be a noop wrt. populating sections, until the range to be added falls in non-mapped area. Nevertheless, I will make this wired to larger memory blocks as you said. -- Oscar Salvador SUSE L3