From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753080AbeBVJPv (ORCPT ); Thu, 22 Feb 2018 04:15:51 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54446 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752892AbeBVJPu (ORCPT ); Thu, 22 Feb 2018 04:15:50 -0500 Date: Thu, 22 Feb 2018 17:15:46 +0800 From: Baoquan He To: linux-kernel@vger.kernel.org, dave.hansen@intel.com Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, mhocko@suse.com, tglx@linutronix.de Subject: Re: [PATCH v2 0/3] mm/sparse: Optimize memmap allocation during sparse_init() Message-ID: <20180222091546.GA693@localhost.localdomain> References: <20180222091130.32165-1-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180222091130.32165-1-bhe@redhat.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/22/18 at 05:11pm, Baoquan He wrote: > This is v2 post. V1 can be found here: > https://www.spinics.net/lists/linux-mm/msg144486.html > > In sparse_init(), two temporary pointer arrays, usemap_map and map_map > are allocated with the size of NR_MEM_SECTIONS. They are used to store > each memory section's usemap and mem map if marked as present. In > 5-level paging mode, this will cost 512M memory though they will be > released at the end of sparse_init(). System with few memory, like > kdump kernel which usually only has about 256M, will fail to boot > because of allocation failure if CONFIG_X86_5LEVEL=y. > > In this patchset, optimize the memmap allocation code to only use > usemap_map and map_map with the size of nr_present_sections. This > makes kdump kernel boot up with normal crashkernel='' setting when > CONFIG_X86_5LEVEL=y. Sorry, forgot adding the change log. v1-v2: Split out the nr_present_sections adding as a single patch for easier reviewing. Rewrite patch log according to Dave's suggestion. Fix code bug in patch 0002 reported by test robot. > > Baoquan He (3): > mm/sparse: Add a static variable nr_present_sections > mm/sparsemem: Defer the ms->section_mem_map clearing > mm/sparse: Optimize memmap allocation during sparse_init() > > mm/sparse-vmemmap.c | 9 +++++---- > mm/sparse.c | 54 +++++++++++++++++++++++++++++++++++------------------ > 2 files changed, 41 insertions(+), 22 deletions(-) > > -- > 2.13.6 >