#!/usr/bin/env python3# SPDX-License-Identifier: GPL-2.0-only## Copyright (C) 2024 Red Hat, Inc. Daniel Bristot de Oliveira <bristot@kernel.org>## This is a sample code about how to use timerlat's timer by any workload# so rtla can measure and provide auto-analysis for the overall latency (IOW# the response time) for a task.## Before running it, you need to dispatch timerlat with -U option in a terminal.# Then # run this script pinned to a CPU on another terminal. For example:## timerlat_load.py 1 -p 95## The "Timerlat IRQ" is the IRQ latency, The thread latency is the latency# for the python process to get the CPU. The Ret from user Timer Latency is# the overall latency. In other words, it is the response time for that# activation.## This is just an example, the load is reading 20MB of data from /dev/full# It is in python because it is easy to read :-) import argparseimport sysimport os parser = argparse.ArgumentParser(description='user-space timerlat thread in Python')parser.add_argument("cpu", help='CPU to run timerlat thread')parser.add_argument("-p", "--prio", help='FIFO priority') args = parser.parse_args() try:    affinity_mask = { int(args.cpu) }except:    print("Invalid cpu: " + args.cpu)    exit(1) try:    os.sched_setaffinity(0, affinity_mask);except:    print("Error setting affinity")    exit(1) if (args.prio):    try:        param = os.sched_param(int(args.prio))        os.sched_setscheduler(0, os.SCHED_FIFO, param)    except:        print("Error setting priority")        exit(1) try:    timerlat_path = "/sys/kernel/tracing/osnoise/per_cpu/cpu" + args.cpu + "/timerlat_fd"    timerlat_fd = open(timerlat_path, 'r')except:    print("Error opening timerlat fd, did you run timerlat -U?")    exit(1) try:    data_fd = open("/dev/full", 'r');except:    print("Error opening data fd") while True:    try:        timerlat_fd.read(1)        data_fd.read(20*1024*1024)    except:        print("Leaving")        break timerlat_fd.close()data_fd.close()