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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 37D08ECDFAA for ; Thu, 12 Jul 2018 21:22:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D611021486 for ; Thu, 12 Jul 2018 21:22:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D611021486 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732991AbeGLVd7 (ORCPT ); Thu, 12 Jul 2018 17:33:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:37250 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732383AbeGLVd7 (ORCPT ); Thu, 12 Jul 2018 17:33:59 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0A060213A2; Thu, 12 Jul 2018 21:22:33 +0000 (UTC) Date: Thu, 12 Jul 2018 17:22:32 -0400 From: Steven Rostedt To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Andy Shevchenko , Boqun Feng , Byungchul Park , Erick Reyes , Ingo Molnar , Julia Cartwright , linux-kselftest@vger.kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , Paul McKenney , Peter Zijlstra , Shuah Khan , Thomas Glexiner , Todd Kjos , Tom Zanussi Subject: Re: [PATCH 1/2] lib: Add module for testing preemptoff/irqsoff latency tracers Message-ID: <20180712172232.00e4c01e@gandalf.local.home> In-Reply-To: <20180711063540.91101-2-joel@joelfernandes.org> References: <20180711063540.91101-1-joel@joelfernandes.org> <20180711063540.91101-2-joel@joelfernandes.org> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Jul 2018 23:35:39 -0700 Joel Fernandes wrote: > > Co-developed-by: Erick Reyes A co-developer needs to add their signed off by. To specify that Erick is a co-author, you could do: [ Erick is a co-developer of this commit ] Signed-off-by: Add Erick's SOB here. > Cc: Andy Shevchenko > Reviewed-by: Andy Shevchenko > Signed-off-by: Joel Fernandes (Google) > --- > kernel/trace/Kconfig | 15 ++++++ > kernel/trace/Makefile | 1 + > kernel/trace/preemptirq_delay_test.c | 72 ++++++++++++++++++++++++++++ > 3 files changed, 88 insertions(+) > create mode 100644 kernel/trace/preemptirq_delay_test.c > > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index 8d51351e3149..eb5ab6b511e2 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -699,6 +699,21 @@ config RING_BUFFER_STARTUP_TEST > > If unsure, say N > > +config PREEMPTIRQ_DELAY_TEST > + tristate "Preempt / IRQ disable delay thread to test latency tracers" > + depends on m > + help > + Select this option to build a test module that can help test latency > + tracers by executing a preempt or irq disable section with a user > + configurable delay. The module busy waits for the duration of the > + critical section. > + > + For example, the following invocation forces a one-time irq-disabled > + critical section for 500us: > + modprobe preemptirq_delay_test test_mode=irq delay=500000 > + > + If unsure, say N > + > config TRACE_EVAL_MAP_FILE > bool "Show eval mappings for trace events" > depends on TRACING > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile > index 84a0cb222f20..677540bb1b62 100644 > --- a/kernel/trace/Makefile > +++ b/kernel/trace/Makefile > @@ -36,6 +36,7 @@ obj-$(CONFIG_TRACING_MAP) += tracing_map.o > obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o > obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o > obj-$(CONFIG_PREEMPTIRQ_TRACEPOINTS) += trace_preemptirq.o > +obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o > obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o > obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o > obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o > diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c > new file mode 100644 > index 000000000000..c97a026c0720 > --- /dev/null > +++ b/kernel/trace/preemptirq_delay_test.c > @@ -0,0 +1,72 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Preempt / IRQ disable delay thread to test latency tracers > + * > + * Copyright (C) 2018 Joel Fernandes (Google) > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +static ulong delay = 100; > +static char test_mode[10] = "irq"; > + > +module_param_named(delay, delay, ulong, S_IRUGO); > +module_param_string(test_mode, test_mode, 10, S_IRUGO); > +MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)"); > +MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)"); > + > +static void busy_wait(ulong time) > +{ > + ktime_t start, end; > + start = ktime_get(); > + do { > + end = ktime_get(); > + if (kthread_should_stop()) > + break; > + } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000)); > +} > + > +int preemptirq_delay_run(void *data) > +{ > + unsigned long flags; > + > + if (!strcmp(test_mode, "irq")) { > + local_irq_save(flags); > + busy_wait(delay); > + local_irq_restore(flags); > + } else if (!strcmp(test_mode, "preempt")) { > + preempt_disable(); > + busy_wait(delay); > + preempt_enable(); > + } > + > + return 0; > +} > + > +static int __init preemptirq_delay_init(void) > +{ > + char task_name[50]; > + struct task_struct *test_task; > + > + snprintf(task_name, sizeof(task_name), "%s_test", test_mode); > + > + test_task = kthread_run(preemptirq_delay_run, NULL, task_name); > + return PTR_ERR_OR_ZERO(test_task); > +} > + > +static void __exit preemptirq_delay_exit(void) > +{ > + return; > +} > + > +module_init(preemptirq_delay_init) > +module_exit(preemptirq_delay_exit) > +MODULE_LICENSE("GPL v2");