From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 9A3B16B0003 for ; Fri, 6 Apr 2018 07:06:43 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id e185so711601wmg.5 for ; Fri, 06 Apr 2018 04:06:43 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id c4sor4997636edk.28.2018.04.06.04.06.42 for (Google Transport Security); Fri, 06 Apr 2018 04:06:42 -0700 (PDT) Date: Fri, 6 Apr 2018 14:05:57 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH v3 0/4] mm/sparse: Optimize memmap allocation during sparse_init() Message-ID: <20180406110557.xg2edtjgzmsdksry@node.shutemov.name> References: <20180228032657.32385-1-bhe@redhat.com> <20180405150842.350e4febc06a813138f00416@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180405150842.350e4febc06a813138f00416@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , dave.hansen@intel.com Cc: Baoquan He , linux-kernel@vger.kernel.org, pagupta@redhat.com, linux-mm@kvack.org, kirill.shutemov@linux.intel.com On Thu, Apr 05, 2018 at 03:08:42PM -0700, Andrew Morton wrote: > On Wed, 28 Feb 2018 11:26:53 +0800 Baoquan He wrote: > > > This is v3 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. > > This patchset could do with some more review, please? I don't really understand sparsemem good enough to comment on the patchset. Dave, could you review this? -- Kirill A. Shutemov