[for-next][PATCH 09/11] rtla/timerlat_top: Add timerlat user-space support

Steven Rostedt
2023-06-13T22:09:09Z

Add the support for running timerlat threads in user-space. In this
mode, enabled with -u/--user-threads, timerlat dispatches user-space
processes that will loop in the timerlat_fd, measuring the overhead
for going to user-space and then returning to the kernel - in addition
to the existing measurements.

Here is one example of the tool's output with -u enabled:

$ sudo timerlat top -u -d 600 -q
Timer Latency
0 00:10:01 | IRQ Timer Latency (us) | Thread Timer Latency (us) | Ret user Timer Latency (us)
CPU COUNT | cur min avg max | cur min avg max | cur min avg max
0 #600001 | 0 0 0 3 | 2 1 2 9 | 3 2 3 15
1 #600001 | 0 0 0 2 | 2 1 2 13 | 2 2 3 18
2 #600001 | 0 0 0 10 | 2 1 2 16 | 3 2 3 20
3 #600001 | 0 0 0 7 | 2 1 2 10 | 3 2 3 11
4 #600000 | 0 0 0 16 | 2 1 2 41 | 3 2 3 58
5 #600000 | 0 0 0 3 | 2 1 2 10 | 3 2 3 13
6 #600000 | 0 0 0 5 | 2 1 2 7 | 3 2 3 10
7 #600000 | 0 0 0 1 | 2 1 2 7 | 3 2 3 10

The tuning setup like -p or -C work for the user-space threads as well.

Link: https://lkml.kernel.org/r/758ad2292a0a1d884138d08219e1a0f572d257a2.1686066600.git.bristot@kernel.org

Cc: William White <chwhite@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
tools/tracing/rtla/src/osnoise.c | 65 ++++++++
tools/tracing/rtla/src/osnoise.h | 5 +
tools/tracing/rtla/src/timerlat_top.c | 108 ++++++++++++-
tools/tracing/rtla/src/timerlat_u.c | 224 ++++++++++++++++++++++++++
tools/tracing/rtla/src/timerlat_u.h | 18 +++
tools/tracing/rtla/src/utils.c | 58 +++++++
tools/tracing/rtla/src/utils.h | 2 +
7 files changed, 474 insertions(+), 6 deletions(-)
create mode 100644 tools/tracing/rtla/src/timerlat_u.c
create mode 100644 tools/tracing/rtla/src/timerlat_u.h

diff --git a/tools/tracing/rtla/src/osnoise.c b/tools/tracing/rtla/src/osnoise.c
index 3ca7a3853943..245e9344932b 100644
--- a/tools/tracing/rtla/src/osnoise.c
+++ b/tools/tracing/rtla/src/osnoise.c
@@ -841,6 +841,67 @@ static void osnoise_put_irq_disable(struct osnoise_context *context)
context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
}

+static int osnoise_get_workload(struct osnoise_context *context)
+{
+ if (context->opt_workload != OSNOISE_OPTION_INIT_VAL)
+ return context->opt_workload;
+
+ if (context->orig_opt_workload != OSNOISE_OPTION_INIT_VAL)
+ return context->orig_opt_workload;
+
+ context->orig_opt_workload = osnoise_options_get_option("OSNOISE_WORKLOAD");
+
+ return context->orig_opt_workload;
+}
+
+int osnoise_set_workload(struct osnoise_context *context, bool onoff)
+{
+ int opt_workload = osnoise_get_workload(context);
+ int retval;
+
+ if (opt_workload == OSNOISE_OPTION_INIT_VAL)
+ return -1;
+
+ if (opt_workload == onoff)
+ return 0;
+
+ retval = osnoise_options_set_option("OSNOISE_WORKLOAD", onoff);
+ if (retval < 0)
+ return -1;
+
+ context->opt_workload = onoff;
+
+ return 0;
+}
+
+static void osnoise_restore_workload(struct osnoise_context *context)
+{
+ int retval;
+
+ if (context->orig_opt_workload == OSNOISE_OPTION_INIT_VAL)
+ return;
+
+ if (context->orig_opt_workload == context->opt_workload)
+ goto out_done;
+
+ retval = osnoise_options_set_option("OSNOISE_WORKLOAD", context->orig_opt_workload);
+ if (retval < 0)
+ err_msg("Could not restore original OSNOISE_WORKLOAD option\n");
+
+out_done:
+ context->orig_opt_workload = OSNOISE_OPTION_INIT_VAL;
+}
+
+static void osnoise_put_workload(struct osnoise_context *context)
+{
+ osnoise_restore_workload(context);
+
+ if (context->orig_opt_workload == OSNOISE_OPTION_INIT_VAL)
+ return;
+
+ context->orig_opt_workload = OSNOISE_OPTION_INIT_VAL;
+}
+
/*
* enable_osnoise - enable osnoise tracer in the trace_instance
*/
@@ -908,6 +969,9 @@ struct osnoise_context *osnoise_context_alloc(void)
context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
context->opt_irq_disable = OSNOISE_OPTION_INIT_VAL;

+ context->orig_opt_workload = OSNOISE_OPTION_INIT_VAL;
+ context->opt_workload = OSNOISE_OPTION_INIT_VAL;
+
osnoise_get_context(context);

return context;
@@ -935,6 +999,7 @@ void osnoise_put_context(struct osnoise_context *context)
osnoise_put_print_stack(context);
osnoise_put_tracing_thresh(context);
osnoise_put_irq_disable(context);
+ osnoise_put_workload(context);

free(context);
}
diff --git a/tools/tracing/rtla/src/osnoise.h b/tools/tracing/rtla/src/osnoise.h
index 4dcf22ccd704..555f4f4903cc 100644
--- a/tools/tracing/rtla/src/osnoise.h
+++ b/tools/tracing/rtla/src/osnoise.h
@@ -42,6 +42,10 @@ struct osnoise_context {
/* -1 as init value because 0 is off */
int orig_opt_irq_disable;
int opt_irq_disable;
+
+ /* -1 as init value because 0 is off */
+ int orig_opt_workload;
+ int opt_workload;
};

/*
@@ -84,6 +88,7 @@ int osnoise_set_print_stack(struct osnoise_context *context,
long long print_stack);

int osnoise_set_irq_disable(struct osnoise_context *context, bool onoff);
+int osnoise_set_workload(struct osnoise_context *context, bool onoff);

/*
* osnoise_tool - osnoise based tool definition.
diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index 02cff4948981..1640f121baca 100644
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -13,11 +13,13 @@
#include <time.h>
#include <errno.h>
#include <sched.h>
+#include <pthread.h>

#include "utils.h"
#include "osnoise.h"
#include "timerlat.h"
#include "timerlat_aa.h"
+#include "timerlat_u.h"

struct timerlat_top_params {
char *cpus;
@@ -40,6 +42,7 @@ struct timerlat_top_params {
int dump_tasks;
int cgroup;
int hk_cpus;
+ int user_top;
cpu_set_t hk_cpu_set;
struct sched_attr sched_param;
struct trace_events *events;
@@ -48,6 +51,7 @@ struct timerlat_top_params {
struct timerlat_top_cpu {
int irq_count;
int thread_count;
+ int user_count;

unsigned long long cur_irq;
unsigned long long min_irq;
@@ -58,6 +62,11 @@ struct timerlat_top_cpu {
unsigned long long min_thread;
unsigned long long sum_thread;
unsigned long long max_thread;
+
+ unsigned long long cur_user;
+ unsigned long long min_user;
+ unsigned long long sum_user;
+ unsigned long long max_user;
};

struct timerlat_top_data {
@@ -98,6 +107,7 @@ static struct timerlat_top_data *timerlat_alloc_top(int nr_cpus)
for (cpu = 0; cpu < nr_cpus; cpu++) {
data->cpu_data[cpu].min_irq = ~0;
data->cpu_data[cpu].min_thread = ~0;
+ data->cpu_data[cpu].min_user = ~0;
}

return data;
@@ -124,12 +134,18 @@ timerlat_top_update(struct osnoise_tool *tool, int cpu,
update_min(&cpu_data->min_irq, &latency);
update_sum(&cpu_data->sum_irq, &latency);
update_max(&cpu_data->max_irq, &latency);
- } else {
+ } else if (thread == 1) {
cpu_data->thread_count++;
cpu_data->cur_thread = latency;
update_min(&cpu_data->min_thread, &latency);
update_sum(&cpu_data->sum_thread, &latency);
update_max(&cpu_data->max_thread, &latency);
+ } else {
+ cpu_data->user_count++;
+ cpu_data->cur_user = latency;
+ update_min(&cpu_data->min_user, &latency);
+ update_sum(&cpu_data->sum_user, &latency);
+ update_max(&cpu_data->max_user, &latency);
}
}

@@ -172,15 +188,25 @@ static void timerlat_top_header(struct osnoise_tool *top)

trace_seq_printf(s, "\033[2;37;40m");
trace_seq_printf(s, " Timer Latency ");
+ if (params->user_top)
+ trace_seq_printf(s, " ");
trace_seq_printf(s, "\033[0;0;0m");
trace_seq_printf(s, "\n");

- trace_seq_printf(s, "%-6s | IRQ Timer Latency (%s) | Thread Timer Latency (%s)\n", duration,
+ trace_seq_printf(s, "%-6s | IRQ Timer Latency (%s) | Thread Timer Latency (%s)", duration,
params->output_divisor == 1 ? "ns" : "us",
params->output_divisor == 1 ? "ns" : "us");

+ if (params->user_top) {
+ trace_seq_printf(s, " | Ret user Timer Latency (%s)",
+ params->output_divisor == 1 ? "ns" : "us");
+ }
+
+ trace_seq_printf(s, "\n");
trace_seq_printf(s, "\033[2;30;47m");
trace_seq_printf(s, "CPU COUNT | cur min avg max | cur min avg max");
+ if (params->user_top)
+ trace_seq_printf(s, " | cur min avg max");
trace_seq_printf(s, "\033[0;0;0m");
trace_seq_printf(s, "\n");
}
@@ -233,7 +259,27 @@ static void timerlat_top_print(struct osnoise_tool *top, int cpu)
trace_seq_printf(s, "%9llu ", cpu_data->min_thread / divisor);
trace_seq_printf(s, "%9llu ",
(cpu_data->sum_thread / cpu_data->thread_count) / divisor);
- trace_seq_printf(s, "%9llu\n", cpu_data->max_thread / divisor);
+ trace_seq_printf(s, "%9llu", cpu_data->max_thread / divisor);
+ }
+
+ if (!params->user_top) {
+ trace_seq_printf(s, "\n");
+ return;
+ }
+
+ trace_seq_printf(s, " |");
+
+ if (!cpu_data->user_count) {
+ trace_seq_printf(s, " - ");
+ trace_seq_printf(s, " - ");
+ trace_seq_printf(s, " - ");
+ trace_seq_printf(s, " -\n");
+ } else {
+ trace_seq_printf(s, "%9llu ", cpu_data->cur_user / divisor);
+ trace_seq_printf(s, "%9llu ", cpu_data->min_user / divisor);
+ trace_seq_printf(s, "%9llu ",
+ (cpu_data->sum_user / cpu_data->user_count) / divisor);
+ trace_seq_printf(s, "%9llu\n", cpu_data->max_user / divisor);
}
}

@@ -288,7 +334,7 @@ static void timerlat_top_usage(char *usage)
"",
" usage: rtla timerlat [top] [-h] [-q] [-a us] [-d s] [-D] [-n] [-p us] [-i us] [-T us] [-s us] \\",
" [[-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] [-H cpu-list]\\",
- " [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]]",
+ " [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]] [-u]",
"",
" -h/--help: print this menu",
" -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
@@ -317,6 +363,7 @@ static void timerlat_top_usage(char *usage)
" f:prio - use SCHED_FIFO with prio",
" 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",
NULL,
};

@@ -371,6 +418,7 @@ static struct timerlat_top_params
{"stack", required_argument, 0, 's'},
{"thread", required_argument, 0, 'T'},
{"trace", optional_argument, 0, 't'},
+ {"user-threads", no_argument, 0, 'u'},
{"trigger", required_argument, 0, '0'},
{"filter", required_argument, 0, '1'},
{"dma-latency", required_argument, 0, '2'},
@@ -383,7 +431,7 @@ 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:0:1:2:345:",
+ c = getopt_long(argc, argv, "a:c:C::d:De:hH:i:np:P:qs:t::T:u0:1:2:345:",
long_options, &option_index);

/* detect the end of the options. */
@@ -498,6 +546,9 @@ static struct timerlat_top_params
else
params->trace_output = "timerlat_trace.txt";

+ break;
+ case 'u':
+ params->user_top = true;
break;
case '0': /* trigger */
if (params->events) {
@@ -563,6 +614,7 @@ static int
timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *params)
{
int retval;
+ int i;

if (!params->sleep_time)
params->sleep_time = 1;
@@ -573,6 +625,9 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
err_msg("Failed to apply CPUs config\n");
goto out_err;
}
+ } else {
+ for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++)
+ CPU_SET(i, &params->monitored_cpus);
}

if (params->stop_us) {
@@ -627,6 +682,14 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
auto_house_keeping(&params->monitored_cpus);
}

+ if (params->user_top) {
+ retval = osnoise_set_workload(top->context, 0);
+ if (retval) {
+ err_msg("Failed to set OSNOISE_WORKLOAD option\n");
+ goto out_err;
+ }
+ }
+
return 0;

out_err:
@@ -687,10 +750,12 @@ int timerlat_top_main(int argc, char *argv[])
{
struct timerlat_top_params *params;
struct osnoise_tool *record = NULL;
+ struct timerlat_u_params params_u;
struct osnoise_tool *top = NULL;
struct osnoise_tool *aa = NULL;
struct trace_instance *trace;
int dma_latency_fd = -1;
+ pthread_t timerlat_u;
int return_value = 1;
char *max_lat;
int retval;
@@ -727,7 +792,7 @@ int timerlat_top_main(int argc, char *argv[])
}
}

- if (params->cgroup) {
+ if (params->cgroup && !params->user_top) {
retval = set_comm_cgroup("timerlat/", params->cgroup_name);
if (!retval) {
err_msg("Failed to move threads to cgroup\n");
@@ -800,6 +865,25 @@ int timerlat_top_main(int argc, char *argv[])
top->start_time = time(NULL);
timerlat_top_set_signals(params);

+ if (params->user_top) {
+ /* rtla asked to stop */
+ params_u.should_run = 1;
+ /* all threads left */
+ params_u.stopped_running = 0;
+
+ params_u.set = &params->monitored_cpus;
+ if (params->set_sched)
+ params_u.sched_param = &params->sched_param;
+ else
+ params_u.sched_param = NULL;
+
+ params_u.cgroup_name = params->cgroup_name;
+
+ retval = pthread_create(&timerlat_u, NULL, timerlat_u_dispatcher, &params_u);
+ if (retval)
+ err_msg("Error creating timerlat user-space threads\n");
+ }
+
while (!stop_tracing) {
sleep(params->sleep_time);

@@ -823,6 +907,18 @@ int timerlat_top_main(int argc, char *argv[])
if (trace_is_off(&top->trace, &record->trace))
break;

+ /* is there still any user-threads ? */
+ if (params->user_top) {
+ if (params_u.stopped_running) {
+ debug_msg("timerlat user space threads stopped!\n");
+ break;
+ }
+ }
+ }
+
+ if (params->user_top && !params_u.stopped_running) {
+ params_u.should_run = 0;
+ sleep(1);
}

timerlat_print_stats(params, top);
diff --git a/tools/tracing/rtla/src/timerlat_u.c b/tools/tracing/rtla/src/timerlat_u.c
new file mode 100644
index 000000000000..05e310696dd5
--- /dev/null
+++ b/tools/tracing/rtla/src/timerlat_u.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
+ */
+
+#define _GNU_SOURCE
+#include <sched.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <tracefs.h>
+#include <pthread.h>
+#include <sys/wait.h>
+#include <sys/prctl.h>
+
+#include "utils.h"
+#include "timerlat_u.h"
+
+/*
+ * This is the user-space main for the tool timerlatu/ threads.
+ *
+ * It is as simple as this:
+ * - set affinity
+ * - set priority
+ * - open tracer fd
+ * - spin
+ * - close
+ */
+static int timerlat_u_main(int cpu, struct timerlat_u_params *params)
+{
+ struct sched_param sp = { .sched_priority = 95 };
+ char buffer[1024];
+ int timerlat_fd;
+ cpu_set_t set;
+ int retval;
+
+ /*
+ * This all is only setting up the tool.
+ */
+ CPU_ZERO(&set);
+ CPU_SET(cpu, &set);
+
+ retval = sched_setaffinity(gettid(), sizeof(set), &set);
+ if (retval == -1) {
+ err_msg("Error setting user thread affinity\n");
+ exit(1);
+ }
+
+ if (!params->sched_param) {
+ retval = sched_setscheduler(0, SCHED_FIFO, &sp);
+ if (retval < 0) {
+ err_msg("Error setting timerlat u default priority: %s\n", strerror(errno));
+ exit(1);
+ }
+ } else {
+ retval = __set_sched_attr(getpid(), params->sched_param);
+ if (retval) {
+ /* __set_sched_attr prints an error message, so */
+ exit(0);
+ }
+ }
+
+ if (params->cgroup_name) {
+ retval = set_pid_cgroup(gettid(), params->cgroup_name);
+ if (!retval) {
+ err_msg("Error setting timerlat u cgroup pid\n");
+ pthread_exit(&retval);
+ }
+ }
+
+ /*
+ * This is the tool's loop. If you want to use as base for your own tool...
+ * go ahead.
+ */
+ snprintf(buffer, sizeof(buffer), "osnoise/per_cpu/cpu%d/timerlat_fd", cpu);
+
+ timerlat_fd = tracefs_instance_file_open(NULL, buffer, O_RDONLY);
+ if (timerlat_fd < 0) {
+ err_msg("Error opening %s:%s\n", buffer, strerror(errno));
+ exit(1);
+ }
+
+ debug_msg("User-space timerlat pid %d on cpu %d\n", gettid(), cpu);
+
+ /* add should continue with a signal handler */
+ while (true) {
+ retval = read(timerlat_fd, buffer, 1024);
+ if (retval < 0)
+ break;
+ }
+
+ close(timerlat_fd);
+
+ debug_msg("Leaving timerlat pid %d on cpu %d\n", gettid(), cpu);
+ exit(0);
+}
+
+/*
+ * timerlat_u_send_kill - send a kill signal for all processes
+ *
+ * Return the number of processes that received the kill.
+ */
+static int timerlat_u_send_kill(pid_t *procs, int nr_cpus)
+{
+ int killed = 0;
+ int i, retval;
+
+ for (i = 0; i < nr_cpus; i++) {
+ if (!procs[i])
+ continue;
+ retval = kill(procs[i], SIGKILL);
+ if (!retval)
+ killed++;
+ else
+ err_msg("Error killing child process %d\n", procs[i]);
+ }
+
+ return killed;
+}
+
+/**
+ * timerlat_u_dispatcher - dispatch one timerlatu/ process per monitored CPU
+ *
+ * This is a thread main that will fork one new process for each monitored
+ * CPU. It will wait for:
+ *
+ * - rtla to tell to kill the child processes
+ * - some child process to die, and the cleanup all the processes
+ *
+ * whichever comes first.
+ *
+ */
+void *timerlat_u_dispatcher(void *data)
+{
+ int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+ struct timerlat_u_params *params = data;
+ char proc_name[128];
+ int procs_count = 0;
+ int retval = 1;
+ pid_t *procs;
+ int wstatus;
+ pid_t pid;
+ int i;
+
+ debug_msg("Dispatching timerlat u procs\n");
+
+ procs = calloc(nr_cpus, sizeof(pid_t));
+ if (!procs)
+ pthread_exit(&retval);
+
+ for (i = 0; i < nr_cpus; i++) {
+ if (params->set && !CPU_ISSET(i, params->set))
+ continue;
+
+ pid = fork();
+
+ /* child */
+ if (!pid) {
+
+ /*
+ * rename the process
+ */
+ snprintf(proc_name, sizeof(proc_name), "timerlatu/%d", i);
+ pthread_setname_np(pthread_self(), proc_name);
+ prctl(PR_SET_NAME, (unsigned long)proc_name, 0, 0, 0);
+
+ timerlat_u_main(i, params);
+ /* timerlat_u_main should exit()! Anyways... */
+ pthread_exit(&retval);
+ }
+
+ /* parent */
+ if (pid == -1) {
+ timerlat_u_send_kill(procs, nr_cpus);
+ debug_msg("Failed to create child processes");
+ pthread_exit(&retval);
+ }
+
+ procs_count++;
+ procs[i] = pid;
+ }
+
+ while (params->should_run) {
+ /* check if processes died */
+ pid = waitpid(-1, &wstatus, WNOHANG);
+ if (pid != 0) {
+ for (i = 0; i < nr_cpus; i++) {
+ if (procs[i] == pid) {
+ procs[i] = 0;
+ procs_count--;
+ }
+ }
+ break;
+ }
+
+ sleep(1);
+ }
+
+ timerlat_u_send_kill(procs, nr_cpus);
+
+ while (procs_count) {
+ pid = waitpid(-1, &wstatus, 0);
+ if (pid == -1) {
+ err_msg("Failed to monitor child processes");
+ pthread_exit(&retval);
+ }
+ for (i = 0; i < nr_cpus; i++) {
+ if (procs[i] == pid) {
+ procs[i] = 0;
+ procs_count--;
+ }
+ }
+ }
+
+ params->stopped_running = 1;
+
+ free(procs);
+ retval = 0;
+ pthread_exit(&retval);
+
+}
diff --git a/tools/tracing/rtla/src/timerlat_u.h b/tools/tracing/rtla/src/timerlat_u.h
new file mode 100644
index 000000000000..661511908957
--- /dev/null
+++ b/tools/tracing/rtla/src/timerlat_u.h
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
+ */
+
+struct timerlat_u_params {
+ /* timerlat -> timerlat_u: user-space threads can keep running */
+ int should_run;
+ /* timerlat_u -> timerlat: all timerlat_u threads left, no reason to continue */
+ int stopped_running;
+
+ /* threads config */
+ cpu_set_t *set;
+ char *cgroup_name;
+ struct sched_attr *sched_param;
+};
+
+void *timerlat_u_dispatcher(void *data);
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 3e25f0277fb9..623a38908ed5 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -626,6 +626,64 @@ static int get_self_cgroup(char *self_cg, int sizeof_self_cg)
return 1;
}

+/*
+ * set_comm_cgroup - Set cgroup to pid_t pid
+ *
+ * If cgroup argument is not NULL, the threads will move to the given cgroup.
+ * Otherwise, the cgroup of the calling, i.e., rtla, thread will be used.
+ *
+ * Supports cgroup v2.
+ *
+ * Returns 1 on success, 0 otherwise.
+ */
+int set_pid_cgroup(pid_t pid, const char *cgroup)
+{
+ char cgroup_path[MAX_PATH - strlen("/cgroup.procs")];
+ char cgroup_procs[MAX_PATH];
+ char pid_str[24];
+ int retval;
+ int cg_fd;
+
+ retval = find_mount("cgroup2", cgroup_path, sizeof(cgroup_path));
+ if (!retval) {
+ err_msg("Did not find cgroupv2 mount point\n");
+ return 0;
+ }
+
+ if (!cgroup) {
+ retval = get_self_cgroup(&cgroup_path[strlen(cgroup_path)],
+ sizeof(cgroup_path) - strlen(cgroup_path));
+ if (!retval) {
+ err_msg("Did not find self cgroup\n");
+ return 0;
+ }
+ } else {
+ snprintf(&cgroup_path[strlen(cgroup_path)],
+ sizeof(cgroup_path) - strlen(cgroup_path), "%s/", cgroup);
+ }
+
+ snprintf(cgroup_procs, MAX_PATH, "%s/cgroup.procs", cgroup_path);
+
+ debug_msg("Using cgroup path at: %s\n", cgroup_procs);
+
+ cg_fd = open(cgroup_procs, O_RDWR);
+ if (cg_fd < 0)
+ return 0;
+
+ snprintf(pid_str, sizeof(pid_str), "%d\n", pid);
+
+ retval = write(cg_fd, pid_str, strlen(pid_str));
+ if (retval < 0)
+ err_msg("Error setting cgroup attributes for pid:%s - %s\n",
+ pid_str, strerror(errno));
+ else
+ debug_msg("Set cgroup attributes for pid:%s\n", pid_str);
+
+ close(cg_fd);
+
+ return (retval >= 0);
+}
+
/**
* set_comm_cgroup - Set cgroup to threads starting with char *comm_prefix
*
diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
index dec59163cfbc..04ed1e650495 100644
--- a/tools/tracing/rtla/src/utils.h
+++ b/tools/tracing/rtla/src/utils.h
@@ -57,8 +57,10 @@ struct sched_attr {

int parse_prio(char *arg, struct sched_attr *sched_param);
int parse_cpu_set(char *cpu_list, cpu_set_t *set);
+int __set_sched_attr(int pid, struct sched_attr *attr);
int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr);
int set_comm_cgroup(const char *comm_prefix, const char *cgroup);
+int set_pid_cgroup(pid_t pid, const char *cgroup);
int set_cpu_dma_latency(int32_t latency);
int auto_house_keeping(cpu_set_t *monitored_cpus);

--
2.39.2