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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 09278C433DB for ; Wed, 24 Feb 2021 18:53:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8C1A64F0B for ; Wed, 24 Feb 2021 18:53:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232392AbhBXSxR (ORCPT ); Wed, 24 Feb 2021 13:53:17 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:58082 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235536AbhBXSve (ORCPT ); Wed, 24 Feb 2021 13:51:34 -0500 Received: from in01.mta.xmission.com ([166.70.13.51]) by out03.mta.xmission.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1lEzF9-00BE5k-Cx; Wed, 24 Feb 2021 11:50:39 -0700 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=fess.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1lEzF8-0003fV-Ej; Wed, 24 Feb 2021 11:50:39 -0700 From: ebiederm@xmission.com (Eric W. Biederman) To: Alexey Gladkov Cc: kernel test robot , 0day robot , LKML , lkp@lists.01.org, ying.huang@intel.com, feng.tang@intel.com, zhengjun.xing@intel.com, io-uring@vger.kernel.org, Kernel Hardening , Linux Containers , linux-mm@kvack.org, Andrew Morton , Christian Brauner , Jann Horn , Jens Axboe , Kees Cook , Linus Torvalds , Oleg Nesterov References: <20210224051845.GB6114@xsang-OptiPlex-9020> <20210224183828.j6uut6sholeo2fzh@example.org> Date: Wed, 24 Feb 2021 12:50:21 -0600 In-Reply-To: <20210224183828.j6uut6sholeo2fzh@example.org> (Alexey Gladkov's message of "Wed, 24 Feb 2021 19:38:28 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1lEzF8-0003fV-Ej;;;mid=;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19uDlW3DrHDIu/oovVJEMOIV0VkW2WC9Yw= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: d28296d248: stress-ng.sigsegv.ops_per_sec -82.7% regression X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Alexey Gladkov writes: > On Wed, Feb 24, 2021 at 10:54:17AM -0600, Eric W. Biederman wrote: >> kernel test robot writes: >> >> > Greeting, >> > >> > FYI, we noticed a -82.7% regression of stress-ng.sigsegv.ops_per_sec due to commit: >> > >> > >> > commit: d28296d2484fa11e94dff65e93eb25802a443d47 ("[PATCH v7 5/7] Reimplement RLIMIT_SIGPENDING on top of ucounts") >> > url: https://github.com/0day-ci/linux/commits/Alexey-Gladkov/Count-rlimits-in-each-user-namespace/20210222-175836 >> > base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next >> > >> > in testcase: stress-ng >> > on test machine: 48 threads Intel(R) Xeon(R) CPU E5-2697 v2 @ 2.70GHz with 112G memory >> > with following parameters: >> > >> > nr_threads: 100% >> > disk: 1HDD >> > testtime: 60s >> > class: interrupt >> > test: sigsegv >> > cpufreq_governor: performance >> > ucode: 0x42e >> > >> > >> > In addition to that, the commit also has significant impact on the >> > following tests: >> >> Thank you. Now we have a sense of where we need to test the performance >> of these changes carefully. > > One of the reasons for this is that I rolled back the patch that changed > the ucounts.count type to atomic_t. Now get_ucounts() is forced to use a > spin_lock to increase the reference count. Which given the hickups with getting a working version seems justified. Now we can add incremental patches on top to improve the performance. Eric