Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-25 20:32:22 +00:00
Code Issues Packages Projects Releases Wiki Activity

tools/rtla: Add -U/--user-load option to timerlat

Browse Source 
The timerlat tracer provides an interface for any application to wait
for the timerlat's periodic wakeup. Currently, rtla timerlat uses it
to dispatch its user-space workload (-u option).

But as the tracer interface is generic, rtla timerlat can also be used
to monitor any workload that uses it. For example, a user might
place their own workload to wait on the tracer interface, and
monitor the results with rtla timerlat.

Add the -U option to rtla timerlat top and hist. With this option, rtla
timerlat will not dispatch its workload but only setting up the
system, waiting for a user to dispatch its workload.

The sample code in this patch is an example of python application
that loops in the timerlat tracer fd.

To use it, dispatch:

 # rtla timerlat -U

In a terminal, then run the python program on another terminal,
specifying the CPU to run it. For example, setting on CPU 1:

 #./timerlat_load.py 1

Then rtla timerlat will start printing the statistics of the
./timerlat_load.py app.

An interesting point is that the "Ret user Timer Latency" value
is the overall response time of the load. The sample load does
a memory copy to exemplify that.

The stop tracing options on rtla timerlat works in this setup
as well, including auto analysis.

Link: https://lkml.kernel.org/r/36e6bcf18fe15c7601048fd4c65aeb193c502cc8.1707229706.git.bristot@kernel.org

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
This commit is contained in:
Daniel Bristot de Oliveira 2024-02-06 15:32:06 +01:00
parent 012e4e77df
commit a23c05fd76
4 changed files with 101 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/tools/rtla/common_timerlat_options.rst
View File

@ -33,3 +33,9 @@
to wait on the timerlat_fd. Once the workload is awakes, it goes to sleep again
adding so the measurement for the kernel-to-user and user-to-kernel to the tracer
output.
**-U**, **--user-load**
Set timerlat to run without workload, waiting for the user to dispatch a per-cpu
task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd.
See linux/tools/rtla/sample/timerlat_load.py for an example of user-load code.

74
tools/tracing/rtla/sample/timerlat_load.py Normal file
View File

@ -0,0 +1,74 @@
#!/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 argparse
import sys
import 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()

16
tools/tracing/rtla/src/timerlat_hist.c
View File

@ -39,6 +39,7 @@ struct timerlat_hist_params {
int hk_cpus;
int no_aa;
int dump_tasks;
int user_workload;
int user_hist;
cpu_set_t hk_cpu_set;
struct sched_attr sched_param;
@ -534,6 +535,7 @@ static void timerlat_hist_usage(char *usage)
" d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period",
" in nanoseconds",
" -u/--user-threads: use rtla user-space threads instead of in-kernel timerlat threads",
" -U/--user-load: enable timerlat for user-defined user-space workload",
NULL,
};
@ -595,6 +597,7 @@ static struct timerlat_hist_params
{"thread", required_argument, 0, 'T'},
{"trace", optional_argument, 0, 't'},
{"user-threads", no_argument, 0, 'u'},
{"user-load", no_argument, 0, 'U'},
{"event", required_argument, 0, 'e'},
{"no-irq", no_argument, 0, '0'},
{"no-thread", no_argument, 0, '1'},
@ -613,7 +616,7 @@ static struct timerlat_hist_params
/* getopt_long stores the option index here. */
int option_index = 0;
c = getopt_long(argc, argv, "a:c:C::b:d:e:E:DhH:i:np:P:s:t::T:u0123456:7:8:9\1",
c = getopt_long(argc, argv, "a:c:C::b:d:e:E:DhH:i:np:P:s:t::T:uU0123456:7:8:9\1",
long_options, &option_index);
/* detect the end of the options. */
@ -724,6 +727,9 @@ static struct timerlat_hist_params
params->trace_output = "timerlat_trace.txt";
break;
case 'u':
params->user_workload = 1;
/* fallback: -u implies in -U */
case 'U':
params->user_hist = 1;
break;
case '0': /* no irq */
@ -985,7 +991,7 @@ int timerlat_hist_main(int argc, char *argv[])
}
}
if (params->cgroup && !params->user_hist) {
if (params->cgroup && !params->user_workload) {
retval = set_comm_cgroup("timerlat/", params->cgroup_name);
if (!retval) {
err_msg("Failed to move threads to cgroup\n");
@ -1049,7 +1055,7 @@ int timerlat_hist_main(int argc, char *argv[])
tool->start_time = time(NULL);
timerlat_hist_set_signals(params);
if (params->user_hist) {
if (params->user_workload) {
/* rtla asked to stop */
params_u.should_run = 1;
/* all threads left */
@ -1086,14 +1092,14 @@ int timerlat_hist_main(int argc, char *argv[])
break;
/* is there still any user-threads ? */
if (params->user_hist) {
if (params->user_workload) {
if (params_u.stopped_running) {
debug_msg("timerlat user-space threads stopped!\n");
break;
}
}
}
if (params->user_hist && !params_u.stopped_running) {
if (params->user_workload && !params_u.stopped_running) {
params_u.should_run = 0;
sleep(1);
}

14
tools/tracing/rtla/src/timerlat_top.c
View File

@ -43,6 +43,7 @@ struct timerlat_top_params {
int cgroup;
int hk_cpus;
int user_top;
int user_workload;
cpu_set_t hk_cpu_set;
struct sched_attr sched_param;
struct trace_events *events;
@ -364,6 +365,7 @@ static void timerlat_top_usage(char *usage)
" d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period",
" in nanoseconds",
" -u/--user-threads: use rtla user-space threads instead of in-kernel timerlat threads",
" -U/--user-load: enable timerlat for user-defined user-space workload",
NULL,
};
@ -423,6 +425,7 @@ static struct timerlat_top_params
{"thread", required_argument, 0, 'T'},
{"trace", optional_argument, 0, 't'},
{"user-threads", no_argument, 0, 'u'},
{"user-load", no_argument, 0, 'U'},
{"trigger", required_argument, 0, '0'},
{"filter", required_argument, 0, '1'},
{"dma-latency", required_argument, 0, '2'},
@ -435,7 +438,7 @@ static struct timerlat_top_params
/* getopt_long stores the option index here. */
int option_index = 0;
c = getopt_long(argc, argv, "a:c:C::d:De:hH:i:np:P:qs:t::T:u0:1:2:345:",
c = getopt_long(argc, argv, "a:c:C::d:De:hH:i:np:P:qs:t::T:uU0:1:2:345:",
long_options, &option_index);
/* detect the end of the options. */
@ -552,6 +555,9 @@ static struct timerlat_top_params
break;
case 'u':
params->user_workload = true;
/* fallback: -u implies -U */
case 'U':
params->user_top = true;
break;
case '0': /* trigger */
@ -869,7 +875,7 @@ int timerlat_top_main(int argc, char *argv[])
top->start_time = time(NULL);
timerlat_top_set_signals(params);
if (params->user_top) {
if (params->user_workload) {
/* rtla asked to stop */
params_u.should_run = 1;
/* all threads left */
@ -912,7 +918,7 @@ int timerlat_top_main(int argc, char *argv[])
break;
/* is there still any user-threads ? */
if (params->user_top) {
if (params->user_workload) {
if (params_u.stopped_running) {
debug_msg("timerlat user space threads stopped!\n");
break;
@ -920,7 +926,7 @@ int timerlat_top_main(int argc, char *argv[])
}
}
if (params->user_top && !params_u.stopped_running) {
if (params->user_workload && !params_u.stopped_running) {
params_u.should_run = 0;
sleep(1);
}