From patchwork Wed Nov 30 18:19:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 27951 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:f944:0:0:0:0:0 with SMTP id q4csp1081237wrr; Wed, 30 Nov 2022 10:22:37 -0800 (PST) X-Google-Smtp-Source: AA0mqf6iDGUra+aHSq/Ny9uOMS3NaBcLXow49c4YJK6bMj7dvjKUFde/3LyAIlCNmHJoN+2X74bx X-Received: by 2002:a17:906:d1c7:b0:7ad:fd3e:7762 with SMTP id bs7-20020a170906d1c700b007adfd3e7762mr38562264ejb.717.1669832557501; Wed, 30 Nov 2022 10:22:37 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1669832557; cv=none; d=google.com; s=arc-20160816; b=WyrrDpym2ggkE/R1cHxDlUUDVWVnsjlJlku/WYoVbjoBL4jVBO1Dn8Akd1JFvjemoW baIU74rBH6YmLsNz3fm188TycWVPAks8K0J4hDP5eVWZA1KjAgcHoBBbFkSXBjtkH6xa 2SZf5XiqDmvqbRodJF7Wz/imGEV3YTjBgF0fHCGMz5j2QTbpQVKBMBoJyDDfn6u5RNYa oNtYRHrzgu4GTq3ds5JTTPR4BvFUPy2eATseiiFI2qot8zUJir6r8dEufvyguXeHCBqN M/f0FTBcWcfqi0D90pXjsEwnzovULDHoZPzZMVK4U5bWVo7mxTdj+qkz1FQVHc8qsyWv ThIA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=CrCE6/+jo/dOOiWNIqaDjwl0gkmLXWk/HSiYsdMiEmM=; b=j1zDHTBG7NKYC9XYb52qD4//XIl7m2LmDbbJ5bIVwjOGFE5nsMhVTtywd0lyKSnMBv zeCMiXmMkN1e41giJ9agxCniY/j/x1O8JmEGPuyWhCwK1EwfIbYQwGNRhNyYGcfctx8E SdLjggOUKrrjFydgpT5ANVQSWxjYi4trvprvIXVJZaPLMLalDqT0SUFBXbhAHivTROWj IphPwp/Cw4cZoNynq7IASAFAgbVnF7gNJiPcDIfeBp6ZsdvY+Mdu15dyXVZicDlGUkp/ hnGXaf9bO3jjxHRNrK8249df3g71QUL1p1mzrvT2n/zkuNyz88zKiMzZJgDB11jpV14P ohxw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=r3K9eMn3; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id ho38-20020a1709070ea600b007bf9de4fe91si2210426ejc.53.2022.11.30.10.22.11; Wed, 30 Nov 2022 10:22:37 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=r3K9eMn3; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230356AbiK3SVP (ORCPT + 99 others); Wed, 30 Nov 2022 13:21:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230288AbiK3SUt (ORCPT ); Wed, 30 Nov 2022 13:20:49 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36CBD1B1D2; Wed, 30 Nov 2022 10:19:23 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C448961B7C; Wed, 30 Nov 2022 18:19:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2DB0BC433B5; Wed, 30 Nov 2022 18:19:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669832362; bh=GqkWc/aqvUjp4eNRfDmezwu0hcf18oKW1m9OVrE63ec=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r3K9eMn3+BfW9qWvFSRyI9shOV4eHkdZD76u+7WzqrQBiOGLbHN0HCfjxJWd4R1RV ij2uIluG0XL/XVC95yexetf1y8mhtdrYvW1JQrFX0Uc+PKq1jGXCknM9CoQ50bKqdK q2PNR/ksD3N2NzWZbdt0xSiOgqekKtl+ATsqfoP08APGSuUBheLeLZt3KDozGJOdqF oWUKpS8nrlzngv4UX0tJoYeDT0emRidPWy/ecExywtXtMnnmZQARZZ4oaF+ORvThdM oscUKipdfHl5dwC/wvHpVzwakJvHdhpOixzA3K07Tkp3rIDEINkSnY3DenkY4+eHK9 vsDkCR6JEGW/g== From: Daniel Bristot de Oliveira To: Daniel Bristot de Oliveira , Steven Rostedt Cc: Masami Hiramatsu , Jonathan Corbet , Juri Lelli , Clark Williams , Bagas Sanjaya , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 2/3] tracing/osnoise: Add preempt and/or irq disabled options Date: Wed, 30 Nov 2022 19:19:10 +0100 Message-Id: X-Mailer: git-send-email 2.32.0 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1750946343378682964?= X-GMAIL-MSGID: =?utf-8?q?1750946343378682964?= The osnoise workload runs with preemption and IRQs enabled in such a way as to allow all sorts of noise to disturb osnoise's execution. hwlat tracer has a similar workload but works with irq disabled, allowing only NMIs and the hardware to generate noise. While thinking about adding an options file to hwlat tracer to allow the system to panic, and other features I was thinking to add, like having a tracepoint at each noise detection, it came to my mind that is easier to make osnoise and also do hardware latency detection than making hwlat "feature compatible" with osnoise. Other points are: - osnoise already has an independent cpu file. - osnoise has a more intuitive interface, e.g., runtime/period vs. window/width (and people often need help remembering what it is). - osnoise: tracepoints - osnoise stop options - osnoise options file itself Moreover, the user-space side (in rtla) is simplified by reusing the existing osnoise code. Finally, people have been asking me about using osnoise for hw latency detection, and I have to explain that it was sufficient but not necessary. These options make it sufficient and necessary. Adding a Suggested-by Clark, as he often asked me about this possibility. Cc: Suggested-by: Clark Williams Cc: Daniel Bristot de Oliveira Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Jonathan Corbet Signed-off-by: Daniel Bristot de Oliveira --- kernel/trace/trace_osnoise.c | 48 ++++++++++++++++++++++++++++++++---- 1 file changed, 43 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 801eba0b5cf8..0ec8bb54180f 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -55,10 +55,17 @@ enum osnoise_options_index { OSN_DEFAULTS = 0, OSN_WORKLOAD, OSN_PANIC_ON_STOP, + OSN_PREEMPT_DISABLE, + OSN_IRQ_DISABLE, OSN_MAX }; -static const char * const osnoise_options_str[OSN_MAX] = { "DEFAULTS", "OSNOISE_WORKLOAD", "PANIC_ON_STOP" }; +static const char * const osnoise_options_str[OSN_MAX] = { + "DEFAULTS", + "OSNOISE_WORKLOAD", + "PANIC_ON_STOP", + "OSNOISE_PREEMPT_DISABLE", + "OSNOISE_IRQ_DISABLE" }; #define OSN_DEFAULT_OPTIONS 0x2 unsigned long osnoise_options = OSN_DEFAULT_OPTIONS; @@ -1308,6 +1315,7 @@ static void notify_new_max_latency(u64 latency) */ static int run_osnoise(void) { + bool irq_disable = test_bit(OSN_IRQ_DISABLE, &osnoise_options); struct osnoise_variables *osn_var = this_cpu_osn_var(); u64 start, sample, last_sample; u64 last_int_count, int_count; @@ -1315,11 +1323,18 @@ static int run_osnoise(void) s64 total, last_total = 0; struct osnoise_sample s; unsigned int threshold; + bool preempt_disable; u64 runtime, stop_in; u64 sum_noise = 0; int hw_count = 0; int ret = -1; + /* + * Disabling preemption is only required if IRQs are enabled, + * and the options is set on. + */ + preempt_disable = !irq_disable && test_bit(OSN_PREEMPT_DISABLE, &osnoise_options); + /* * Considers the current thread as the workload. */ @@ -1335,6 +1350,15 @@ static int run_osnoise(void) */ threshold = tracing_thresh ? : 5000; + /* + * Apply PREEMPT and IRQ disabled options. + */ + if (irq_disable) + local_irq_disable(); + + if (preempt_disable) + preempt_disable(); + /* * Make sure NMIs see sampling first */ @@ -1422,16 +1446,21 @@ static int run_osnoise(void) * cond_resched() */ if (IS_ENABLED(CONFIG_PREEMPT_RCU)) { - local_irq_disable(); + if (!irq_disable) + local_irq_disable(); + rcu_momentary_dyntick_idle(); - local_irq_enable(); + + if (!irq_disable) + local_irq_enable(); } /* * For the non-preemptive kernel config: let threads runs, if - * they so wish. + * they so wish, unless set not do to so. */ - cond_resched(); + if (!irq_disable && !preempt_disable) + cond_resched(); last_sample = sample; last_int_count = int_count; @@ -1450,6 +1479,15 @@ static int run_osnoise(void) */ barrier(); + /* + * Return to the preemptive state. + */ + if (preempt_disable) + preempt_enable(); + + if (irq_disable) + local_irq_enable(); + /* * Save noise info. */