From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 0615E6B02AF for ; Mon, 2 Jul 2018 22:00:58 -0400 (EDT) Received: by mail-pl0-f69.google.com with SMTP id ba8-v6so300124plb.4 for ; Mon, 02 Jul 2018 19:00:57 -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 z9-v6sor4960105pfh.136.2018.07.02.19.00.56 for (Google Transport Security); Mon, 02 Jul 2018 19:00:56 -0700 (PDT) Subject: Re: [PATCH v9 0/6] optimize memblock_next_valid_pfn and early_pfn_valid on arm and arm64 References: <1530239363-2356-1-git-send-email-hejianet@gmail.com> <20180702114037.GJ19043@dhcp22.suse.cz> From: Jia He Message-ID: <1466b490-76f8-86a4-f39a-3bef3bb0501f@gmail.com> Date: Tue, 3 Jul 2018 10:00:34 +0800 MIME-Version: 1.0 In-Reply-To: <20180702114037.GJ19043@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Russell King , Andrew Morton , Catalin Marinas , Mel Gorman , Will Deacon , Mark Rutland , "H. Peter Anvin" , Pavel Tatashin , Daniel Jordan , AKASHI Takahiro , Gioh Kim , Steven Sistare , Daniel Vacek , Eugeniu Rosca , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, James Morse , Ard Biesheuvel , Steve Capper , Thomas Gleixner , Ingo Molnar , Greg Kroah-Hartman , Kate Stewart , Philippe Ombredanne , Johannes Weiner , Kemi Wang , Petr Tesarik , YASUAKI ISHIMATSU , Andrey Ryabinin , Nikolay Borisov , richard.weiyang@gmail.com Hi Michal Thanks for the comments On 7/2/2018 7:40 PM, Michal Hocko Wrote: > On Fri 29-06-18 10:29:17, Jia He wrote: >> Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns >> where possible") tried to optimize the loop in memmap_init_zone(). But >> there is still some room for improvement. > > It would be great to shortly describe those optimization from high level > POV. Ok > >> >> Patch 1 introduce new config to make codes more generic >> Patch 2 remain the memblock_next_valid_pfn on arm and arm64 >> Patch 3 optimizes the memblock_next_valid_pfn() >> Patch 4~6 optimizes the early_pfn_valid() >> >> As for the performance improvement, after this set, I can see the time >> overhead of memmap_init() is reduced from 27956us to 13537us in my >> armv8a server(QDF2400 with 96G memory, pagesize 64k). > > So this is 13ms saving when booting 96G machine. Is this really worth > the additional code? Are there any other benefits? hmm.. Currently my answer is no. But I believe it can shorten the boot time when the memory is larger than n TBs. -- Cheers, Jia > [...] >> arch/arm/Kconfig | 4 +++ >> arch/arm/mm/init.c | 1 + >> arch/arm64/Kconfig | 4 +++ >> arch/arm64/mm/init.c | 1 + >> include/linux/early_pfn.h | 79 +++++++++++++++++++++++++++++++++++++++++++++++ >> include/linux/memblock.h | 2 ++ >> include/linux/mmzone.h | 18 ++++++++++- >> mm/Kconfig | 3 ++ >> mm/memblock.c | 9 ++++++ >> mm/page_alloc.c | 5 ++- >> 10 files changed, 124 insertions(+), 2 deletions(-) >> create mode 100644 include/linux/early_pfn.h >