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 3FF86C54EBC for ; Tue, 10 Jan 2023 12:23:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238455AbjAJMXV (ORCPT ); Tue, 10 Jan 2023 07:23:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235172AbjAJMWz (ORCPT ); Tue, 10 Jan 2023 07:22:55 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90C475F49; Tue, 10 Jan 2023 04:20:20 -0800 (PST) Received: from dggpemm500006.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Nrqc40JrVzJrHc; Tue, 10 Jan 2023 20:19:00 +0800 (CST) 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 15.1.2375.34; Tue, 10 Jan 2023 20:20:16 +0800 Subject: Re: [PATCH v2] kallsyms: Fix sleeping function called from invalid context when CONFIG_KALLSYMS_SELFTEST=y To: Petr Mladek , Luis Chamberlain CC: , , Anders Roxell References: <20221228014511.328-1-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <5fdf54c7-7b21-66ca-944e-aa8dde4e3427@huawei.com> Date: Tue, 10 Jan 2023 20:20:16 +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: dggems703-chm.china.huawei.com (10.3.19.180) 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 2023/1/10 17:57, Petr Mladek wrote: > On Mon 2023-01-09 16:12:53, Luis Chamberlain wrote: >> On Mon, Jan 09, 2023 at 02:40:27PM +0100, Petr Mladek wrote: >>> Why are try hardly comparable? >>> >>> 1. The speed depends on the number of loaded modules >>> and number of symbols. It highly depends on the configuration >>> that was used to build the kernel. >>> >>> 2. The test runs only once. As a result it is hard to judge >>> how big is the noise. >>> >>> 3. The noise might depend on the size and state of CPU caches. >>> >>> >>> I personally vote for removing this selftest! >> >> Even so, just as with testing a filesystem with different types of >> configurations, at least testing a few configs helps and it's what >> we do. Then, if anyone ever wanted to try to increase performance >> on symbol lookup today they have no easy way to measure things. How >> would they go about comparing things performance without this selftest? > > How many people cares about kallsyms performance, please? > Is it worth spending time one implementing and maintaining such a > selftest? > > Yes, Zhen wanted to make it faster. But how likely will anyone else > try to make it even better? Do we need to spend time on this > in the meantime? > > >> This selftests helps generically with that *and* helps peg on to it any sanity >> checks you may wish to add to those APIs which we just don't want to do >> upstream. > >>>From my POV, it would be much more important to check if the API > works as expected. I mean that it gives the right results. > > I am not sure that performance is that important to spend more time > on this one. > > Also I am not sure if selftests are the right location for performance > tests. My understanding is that it is a framework for functional > testing. It is showing if the tests passed or not. But performance > tests do not give "pass or not" results. I think both of you have a point. In the absence of a better way to improve it, perhaps deleting the performance test is the best option now. OK, I'll do this first. > > Best Regards, > Petr > . > -- Regards, Zhen Lei