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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 4B8BFC433F5 for ; Wed, 5 Sep 2018 21:58:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D30D2073D for ; Wed, 5 Sep 2018 21:58:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0D30D2073D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727947AbeIFCaG (ORCPT ); Wed, 5 Sep 2018 22:30:06 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59808 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727572AbeIFCaG (ORCPT ); Wed, 5 Sep 2018 22:30:06 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 6D1AA10AF; Wed, 5 Sep 2018 21:57:56 +0000 (UTC) Date: Wed, 5 Sep 2018 14:57:55 -0700 From: Andrew Morton To: Jia He Cc: Russell King , Catalin Marinas , Will Deacon , Mark Rutland , Ard Biesheuvel , Michal Hocko , Wei Yang , Kees Cook , Laura Abbott , Vladimir Murzin , Philip Derrin , AKASHI Takahiro , James Morse , Steve Capper , Gioh Kim , Vlastimil Babka , Mel Gorman , Johannes Weiner , Kemi Wang , Petr Tesarik , YASUAKI ISHIMATSU , Andrey Ryabinin , Nikolay Borisov , Daniel Jordan , Daniel Vacek , Eugeniu Rosca , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jia He Subject: Re: [PATCH v11 0/3] remain and optimize memblock_next_valid_pfn on arm and arm64 Message-Id: <20180905145755.cc89819d446f311e4b8e8f95@linux-foundation.org> In-Reply-To: <1534907237-2982-1-git-send-email-jia.he@hxt-semitech.com> References: <1534907237-2982-1-git-send-email-jia.he@hxt-semitech.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Aug 2018 11:07:14 +0800 Jia He wrote: > Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns > where possible") optimized the loop in memmap_init_zone(). But it causes > possible panic bug. So Daniel Vacek reverted it later. > > But as suggested by Daniel Vacek, it is fine to using memblock to skip > gaps and finding next valid frame with CONFIG_HAVE_ARCH_PFN_VALID. > > More from what Daniel said: > "On arm and arm64, memblock is used by default. But generic version of > pfn_valid() is based on mem sections and memblock_next_valid_pfn() does > not always return the next valid one but skips more resulting in some > valid frames to be skipped (as if they were invalid). And that's why > kernel was eventually crashing on some !arm machines." > > About the performance consideration: > As said by James in b92df1de5, > "I have tested this patch on a virtual model of a Samurai CPU with a > sparse memory map. The kernel boot time drops from 109 to 62 seconds." > Thus it would be better if we remain memblock_next_valid_pfn on arm/arm64. > > Besides we can remain memblock_next_valid_pfn, there is still some room > for 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). I believe arm server will benefit more if memory is > larger than TBs Thanks. I switched to v11. It would be nice to see some confirmation from ARM people please? From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org (Andrew Morton) Date: Wed, 5 Sep 2018 14:57:55 -0700 Subject: [PATCH v11 0/3] remain and optimize memblock_next_valid_pfn on arm and arm64 In-Reply-To: <1534907237-2982-1-git-send-email-jia.he@hxt-semitech.com> References: <1534907237-2982-1-git-send-email-jia.he@hxt-semitech.com> Message-ID: <20180905145755.cc89819d446f311e4b8e8f95@linux-foundation.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 22 Aug 2018 11:07:14 +0800 Jia He wrote: > Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns > where possible") optimized the loop in memmap_init_zone(). But it causes > possible panic bug. So Daniel Vacek reverted it later. > > But as suggested by Daniel Vacek, it is fine to using memblock to skip > gaps and finding next valid frame with CONFIG_HAVE_ARCH_PFN_VALID. > > More from what Daniel said: > "On arm and arm64, memblock is used by default. But generic version of > pfn_valid() is based on mem sections and memblock_next_valid_pfn() does > not always return the next valid one but skips more resulting in some > valid frames to be skipped (as if they were invalid). And that's why > kernel was eventually crashing on some !arm machines." > > About the performance consideration: > As said by James in b92df1de5, > "I have tested this patch on a virtual model of a Samurai CPU with a > sparse memory map. The kernel boot time drops from 109 to 62 seconds." > Thus it would be better if we remain memblock_next_valid_pfn on arm/arm64. > > Besides we can remain memblock_next_valid_pfn, there is still some room > for 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). I believe arm server will benefit more if memory is > larger than TBs Thanks. I switched to v11. It would be nice to see some confirmation from ARM people please?