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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEDC4C43217 for ; Wed, 2 Nov 2022 09:20:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229964AbiKBJU6 (ORCPT ); Wed, 2 Nov 2022 05:20:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231463AbiKBJUi (ORCPT ); Wed, 2 Nov 2022 05:20:38 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BEE3225; Wed, 2 Nov 2022 02:18:28 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4N2LnT481WzpW9X; Wed, 2 Nov 2022 17:14:53 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 2 Nov 2022 17:18:26 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 2 Nov 2022 17:18:25 +0800 Subject: Re: [PATCH v7 00/11] kallsyms: Optimizes the performance of lookup symbols From: "Leizhen (ThunderTown)" To: Luis Chamberlain CC: Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , , , Masahiro Yamada , Alexei Starovoitov , Jiri Olsa , Kees Cook , Andrew Morton , , Steven Rostedt , "Ingo Molnar" References: <20221017064950.2038-1-thunder.leizhen@huawei.com> <77f1c8f0-5e67-0e57-9285-15ba613044fb@huawei.com> <4f06547b-456f-e1ec-c535-16577f502ff1@huawei.com> <712fae84-aadc-7d29-f311-a3352bab6346@huawei.com> Message-ID: Date: Wed, 2 Nov 2022 17:18:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/10/31 23:04, Leizhen (ThunderTown) wrote: > Now, we need to make a decision. Choose one of the two: > 1. Continue with my current approach. Improve the average performance of > kallsyms_lookup_name() by 20 to 30 times. The memory overhead is increased by: > arm64 (defconfig): > 73.5KiB and 4.0% if CONFIG_KALLSYMS_ALL=y. > 19.8KiB and 2.8% if CONFIG_KALLSYMS_ALL=n. > x86 (defconfig): > 49.0KiB and 3.0% if CONFIG_KALLSYMS_ALL=y. > 16.8KiB and 2.3% if CONFIG_KALLSYMS_ALL=n. > 2. Sort names, binary search (The static function causes duplicate names. Additional work is required） > 2^18=262144, only up to 18 symbol expansions and comparisons are required. > The performance is definitely excellent, although I haven't tested it yet. > The memory overhead is increased by: 6 * kallsyms_num_syms > arm64 (defconfig): > 1MiB if CONFIG_KALLSYMS_ALL=y. > 362KiB if CONFIG_KALLSYMS_ALL=n. > x86 (defconfig): > 770KiB if CONFIG_KALLSYMS_ALL=y. > 356KiB if CONFIG_KALLSYMS_ALL=n. Hi, Luis: I've implemented v8 based on method 2(Sort names, binary search). The memory overhead is increased by: 3 * kallsyms_num_syms. kallsyms_offsets_of_names[] is not added in v8 because it does not help much in performance improvement, so save (3 * kallsyms_num_syms) bytes. For details about the performance data, please see the commit message. -- Regards, Zhen Lei