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 DB513C6FA82 for ; Fri, 9 Sep 2022 01:17:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229796AbiIIBRr (ORCPT ); Thu, 8 Sep 2022 21:17:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229610AbiIIBRp (ORCPT ); Thu, 8 Sep 2022 21:17:45 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F17E1098EF; Thu, 8 Sep 2022 18:17:44 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MNyfb0P30zZcl8; Fri, 9 Sep 2022 09:13:11 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 9 Sep 2022 09:17:41 +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 15.1.2375.24; Fri, 9 Sep 2022 09:17:40 +0800 Subject: Re: [PATCH 0/7] kallsyms: Optimizes the performance of lookup symbols To: Luis Chamberlain CC: Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , , , Masahiro Yamada , Alexei Starovoitov , Jiri Olsa , Kees Cook , Andrew Morton , References: <20220908130936.674-1-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <0e662541-baf8-1074-06bd-1398bdf7c2a7@huawei.com> Date: Fri, 9 Sep 2022 09:17:28 +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: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) 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 2022/9/9 8:07, Luis Chamberlain wrote: > On Thu, Sep 08, 2022 at 09:09:29PM +0800, Zhen Lei wrote: >> Currently, to search for a symbol, we need to expand the symbols in >> 'kallsyms_names' one by one, and then use the expanded string for >> comparison. This is very slow. >> >> In fact, we can first compress the name being looked up and then use >> it for comparison when traversing 'kallsyms_names'. >> >> This patch series optimizes the performance of function kallsyms_lookup_name(), >> and function klp_find_object_symbol() in the livepatch module. Based on the >> test results, the performance overhead is reduced to 5%. That is, the >> performance of these functions is improved by 20 times. >> >> To avoid increasing the kernel size in non-debug mode, the optimization is only >> for the case CONFIG_KALLSYMS_ALL=y. > > WIthout having time yet to reveiw the implementation details, it would > seem this is an area we may want to test for future improvements easily, > so a selftest better yet a kunit test may be nice for this. Can you > write one so we can easily gather a simple metric for "how long does > this take"? Good advice. I'll write it today. > > Luis > . > -- Regards, Zhen Lei