On Tue, 10 Jul 2018 23:35:39 -0700
Joel Fernandes <j...@joelfernandes.org> wrote:
>
> Co-developed-by: Erick Reyes <erickre...@google.com>
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 <andriy.shevche...@linux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
> Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org>
> ---
> 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) <j...@joelfernandes.org>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/kthread.h>
> +#include <linux/ktime.h>
> +#include <linux/module.h>
> +#include <linux/printk.h>
> +#include <linux/string.h>
> +
> +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");
