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