From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id EC6C06B0003 for ; Thu, 7 Jun 2018 18:17:19 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id y8-v6so5109747pfl.17 for ; Thu, 07 Jun 2018 15:17:19 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id 33-v6si53943069plo.505.2018.06.07.15.17.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Jun 2018 15:17:18 -0700 (PDT) Date: Thu, 7 Jun 2018 15:17:17 -0700 From: Andrew Morton Subject: Re: [PATCH v4 0/4] mm/sparse: Optimize memmap allocation during sparse_init() Message-Id: <20180607151717.618eea26c03c124c79ad50d0@linux-foundation.org> In-Reply-To: <20180521101555.25610-1-bhe@redhat.com> References: <20180521101555.25610-1-bhe@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Baoquan He Cc: linux-kernel@vger.kernel.org, dave.hansen@intel.com, pagupta@redhat.com, linux-mm@kvack.org, kirill.shutemov@linux.intel.com On Mon, 21 May 2018 18:15:51 +0800 Baoquan He wrote: > This is v4 post. V3 can be found here: > https://lkml.org/lkml/2018/2/27/928 > > 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. We're still a bit short on review input for this series. Hi, Dave!