[PATCH V2 1/9] rtla: Add -C cgroup support

From: Daniel Bristot de Oliveira
Date: Tue May 23 2023 - 13:45:00 EST

The -C option sets a cgroup to the tracer's threads. If the -C option is
passed without arguments, the tracer's thread will inherit rtla's
cgroup. Otherwise, the threads will be placed on the cgroup passed
to the option.

Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
Documentation/tools/rtla/common_options.rst | 4 +
tools/tracing/rtla/src/osnoise_hist.c | 26 ++-
tools/tracing/rtla/src/osnoise_top.c | 26 ++-
tools/tracing/rtla/src/timerlat_hist.c | 27 ++-
tools/tracing/rtla/src/timerlat_top.c | 26 ++-
tools/tracing/rtla/src/utils.c | 185 ++++++++++++++++++++
tools/tracing/rtla/src/utils.h | 1 +
7 files changed, 286 insertions(+), 9 deletions(-)

diff --git a/Documentation/tools/rtla/common_options.rst b/Documentation/tools/rtla/common_options.rst
index af76df6205d4..ede07359d93c 100644
--- a/Documentation/tools/rtla/common_options.rst
+++ b/Documentation/tools/rtla/common_options.rst
@@ -42,6 +42,10 @@
- *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.

+**-C**, **--cgroup**\[*=cgroup*]
+
+ Set a *cgroup* to the tracer's threads. If the **-C** option is passed without arguments, the tracer's thread will inherit **rtla**'s *cgroup*. Otherwise, the threads will be placed on the *cgroup* passed to the option.
+
**-h**, **--help**

Print help menu.
diff --git a/tools/tracing/rtla/src/osnoise_hist.c b/tools/tracing/rtla/src/osnoise_hist.c
index 13e1233690bb..076f4c6af3dd 100644
--- a/tools/tracing/rtla/src/osnoise_hist.c
+++ b/tools/tracing/rtla/src/osnoise_hist.c
@@ -19,6 +19,7 @@ struct osnoise_hist_params {
char *cpus;
char *monitored_cpus;
char *trace_output;
+ char *cgroup_name;
unsigned long long runtime;
unsigned long long period;
long long threshold;
@@ -28,6 +29,7 @@ struct osnoise_hist_params {
int duration;
int set_sched;
int output_divisor;
+ int cgroup;
struct sched_attr sched_param;
struct trace_events *events;

@@ -433,7 +435,7 @@ static void osnoise_hist_usage(char *usage)
" usage: rtla osnoise hist [-h] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\",
" [-T us] [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
" [-c cpu-list] [-P priority] [-b N] [-E N] [--no-header] [--no-summary] [--no-index] \\",
- " [--with-zeros]",
+ " [--with-zeros] [-C[=cgroup_name]]",
"",
" -h/--help: print this menu",
" -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit",
@@ -443,6 +445,7 @@ static void osnoise_hist_usage(char *usage)
" -S/--stop-total us: stop trace if the total sample is higher than the argument in us",
" -T/--threshold us: the minimum delta to be considered a noise",
" -c/--cpus cpu-list: list of cpus to run osnoise threads",
+ " -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
" -d/--duration time[s|m|h|d]: duration of the session",
" -D/--debug: print debug info",
" -t/--trace[=file]: save the stopped trace to [file|osnoise_trace.txt]",
@@ -501,6 +504,7 @@ static struct osnoise_hist_params
{"bucket-size", required_argument, 0, 'b'},
{"entries", required_argument, 0, 'E'},
{"cpus", required_argument, 0, 'c'},
+ {"cgroup", optional_argument, 0, 'C'},
{"debug", no_argument, 0, 'D'},
{"duration", required_argument, 0, 'd'},
{"help", no_argument, 0, 'h'},
@@ -524,7 +528,7 @@ static struct osnoise_hist_params
/* getopt_long stores the option index here. */
int option_index = 0;

- c = getopt_long(argc, argv, "a:c:b:d:e:E:Dhp:P:r:s:S:t::T:01234:5:",
+ c = getopt_long(argc, argv, "a:c:C::b:d:e:E:Dhp:P:r:s:S:t::T:01234:5:",
long_options, &option_index);

/* detect the end of the options. */
@@ -554,6 +558,16 @@ static struct osnoise_hist_params
osnoise_hist_usage("\nInvalid -c cpu list\n");
params->cpus = optarg;
break;
+ case 'C':
+ params->cgroup = 1;
+ if (!optarg) {
+ /* will inherit this cgroup */
+ params->cgroup_name = NULL;
+ } else if (*optarg == '=') {
+ /* skip the = */
+ params->cgroup_name = ++optarg;
+ }
+ break;
case 'D':
config_debug = 1;
break;
@@ -816,6 +830,14 @@ int osnoise_hist_main(int argc, char *argv[])
}
}

+ if (params->cgroup) {
+ retval = set_comm_cgroup("timerlat/", params->cgroup_name);
+ if (!retval) {
+ err_msg("Failed to move threads to cgroup\n");
+ goto out_free;
+ }
+ }
+
trace_instance_start(trace);

if (params->trace_output) {
diff --git a/tools/tracing/rtla/src/osnoise_top.c b/tools/tracing/rtla/src/osnoise_top.c
index 562f2e4b18c5..139d8d392540 100644
--- a/tools/tracing/rtla/src/osnoise_top.c
+++ b/tools/tracing/rtla/src/osnoise_top.c
@@ -26,6 +26,7 @@ struct osnoise_top_params {
char *cpus;
char *monitored_cpus;
char *trace_output;
+ char *cgroup_name;
unsigned long long runtime;
unsigned long long period;
long long threshold;
@@ -35,6 +36,7 @@ struct osnoise_top_params {
int duration;
int quiet;
int set_sched;
+ int cgroup;
struct sched_attr sched_param;
struct trace_events *events;
enum osnoise_mode mode;
@@ -276,7 +278,7 @@ static void osnoise_top_usage(struct osnoise_top_params *params, char *usage)
static const char * const msg[] = {
" [-h] [-q] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\",
" [-T us] [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
- " [-c cpu-list] [-P priority]",
+ " [-c cpu-list] [-P priority] [-C[=cgroup_name]]",
"",
" -h/--help: print this menu",
" -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit",
@@ -286,6 +288,7 @@ static void osnoise_top_usage(struct osnoise_top_params *params, char *usage)
" -S/--stop-total us: stop trace if the total sample is higher than the argument in us",
" -T/--threshold us: the minimum delta to be considered a noise",
" -c/--cpus cpu-list: list of cpus to run osnoise threads",
+ " -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
" -d/--duration time[s|m|h|d]: duration of the session",
" -D/--debug: print debug info",
" -t/--trace[=file]: save the stopped trace to [file|osnoise_trace.txt]",
@@ -347,6 +350,7 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
static struct option long_options[] = {
{"auto", required_argument, 0, 'a'},
{"cpus", required_argument, 0, 'c'},
+ {"cgroup", optional_argument, 0, 'C'},
{"debug", no_argument, 0, 'D'},
{"duration", required_argument, 0, 'd'},
{"event", required_argument, 0, 'e'},
@@ -367,7 +371,7 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
/* getopt_long stores the option index here. */
int option_index = 0;

- c = getopt_long(argc, argv, "a:c:d:De:hp:P:qr:s:S:t::T:0:1:",
+ c = getopt_long(argc, argv, "a:c:C::d:De:hp:P:qr:s:S:t::T:0:1:",
long_options, &option_index);

/* Detect the end of the options. */
@@ -392,6 +396,16 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
osnoise_top_usage(params, "\nInvalid -c cpu list\n");
params->cpus = optarg;
break;
+ case 'C':
+ params->cgroup = 1;
+ if (!optarg) {
+ /* will inherit this cgroup */
+ params->cgroup_name = NULL;
+ } else if (*optarg == '=') {
+ /* skip the = */
+ params->cgroup_name = ++optarg;
+ }
+ break;
case 'D':
config_debug = 1;
break;
@@ -643,6 +657,14 @@ int osnoise_top_main(int argc, char **argv)
}
}

+ if (params->cgroup) {
+ retval = set_comm_cgroup("osnoise/", params->cgroup_name);
+ if (!retval) {
+ err_msg("Failed to move threads to cgroup\n");
+ goto out_free;
+ }
+ }
+
trace_instance_start(trace);

if (params->trace_output) {
diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index 4b48af8a8309..459c159923e8 100644
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -19,6 +19,7 @@ struct timerlat_hist_params {
char *cpus;
char *monitored_cpus;
char *trace_output;
+ char *cgroup_name;
unsigned long long runtime;
long long stop_us;
long long stop_total_us;
@@ -29,9 +30,9 @@ struct timerlat_hist_params {
int duration;
int set_sched;
int dma_latency;
+ int cgroup;
struct sched_attr sched_param;
struct trace_events *events;
-
char no_irq;
char no_thread;
char no_header;
@@ -433,7 +434,7 @@ static void timerlat_hist_usage(char *usage)
" usage: [rtla] timerlat hist [-h] [-q] [-d s] [-D] [-n] [-a us] [-p us] [-i us] [-T us] [-s us] \\",
" [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] \\",
" [-P priority] [-E N] [-b N] [--no-irq] [--no-thread] [--no-header] [--no-summary] \\",
- " [--no-index] [--with-zeros] [--dma-latency us]",
+ " [--no-index] [--with-zeros] [--dma-latency us] [-C[=cgroup_name]]",
"",
" -h/--help: print this menu",
" -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
@@ -442,6 +443,7 @@ static void timerlat_hist_usage(char *usage)
" -T/--thread us: stop trace if the thread latency is higher than the argument in us",
" -s/--stack us: save the stack trace at the IRQ if a thread latency is higher than the argument in us",
" -c/--cpus cpus: run the tracer only on the given cpus",
+ " -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
" -d/--duration time[m|h|d]: duration of the session in seconds",
" -D/--debug: print debug info",
" -t/--trace[=file]: save the stopped trace to [file|timerlat_trace.txt]",
@@ -506,6 +508,7 @@ static struct timerlat_hist_params
static struct option long_options[] = {
{"auto", required_argument, 0, 'a'},
{"cpus", required_argument, 0, 'c'},
+ {"cgroup", optional_argument, 0, 'C'},
{"bucket-size", required_argument, 0, 'b'},
{"debug", no_argument, 0, 'D'},
{"entries", required_argument, 0, 'E'},
@@ -534,7 +537,7 @@ static struct timerlat_hist_params
/* getopt_long stores the option index here. */
int option_index = 0;

- c = getopt_long(argc, argv, "a:c:b:d:e:E:Dhi:np:P:s:t::T:0123456:7:8:",
+ c = getopt_long(argc, argv, "a:c:C::b:d:e:E:Dhi:np:P:s:t::T:0123456:7:8:",
long_options, &option_index);

/* detect the end of the options. */
@@ -561,6 +564,16 @@ static struct timerlat_hist_params
timerlat_hist_usage("\nInvalid -c cpu list\n");
params->cpus = optarg;
break;
+ case 'C':
+ params->cgroup = 1;
+ if (!optarg) {
+ /* will inherit this cgroup */
+ params->cgroup_name = NULL;
+ } else if (*optarg == '=') {
+ /* skip the = */
+ params->cgroup_name = ++optarg;
+ }
+ break;
case 'b':
params->bucket_size = get_llong_from_str(optarg);
if ((params->bucket_size == 0) || (params->bucket_size >= 1000000))
@@ -840,6 +853,14 @@ int timerlat_hist_main(int argc, char *argv[])
}
}

+ if (params->cgroup) {
+ retval = set_comm_cgroup("timerlat/", params->cgroup_name);
+ if (!retval) {
+ err_msg("Failed to move threads to cgroup\n");
+ goto out_free;
+ }
+ }
+
if (params->dma_latency >= 0) {
dma_latency_fd = set_cpu_dma_latency(params->dma_latency);
if (dma_latency_fd < 0) {
diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index 92c658c64f28..a19cbc2aa1f4 100644
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -21,6 +21,7 @@ struct timerlat_top_params {
char *cpus;
char *monitored_cpus;
char *trace_output;
+ char *cgroup_name;
unsigned long long runtime;
long long stop_us;
long long stop_total_us;
@@ -35,6 +36,7 @@ struct timerlat_top_params {
int no_aa;
int aa_only;
int dump_tasks;
+ int cgroup;
struct sched_attr sched_param;
struct trace_events *events;
};
@@ -285,7 +287,7 @@ 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] \\",
- " [-P priority] [--dma-latency us] [--aa-only us]",
+ " [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]]",
"",
" -h/--help: print this menu",
" -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
@@ -295,6 +297,7 @@ static void timerlat_top_usage(char *usage)
" -T/--thread us: stop trace if the thread latency is higher than the argument in us",
" -s/--stack us: save the stack trace at the IRQ if a thread latency is higher than the argument in us",
" -c/--cpus cpus: run the tracer only on the given cpus",
+ " -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
" -d/--duration time[m|h|d]: duration of the session in seconds",
" -D/--debug: print debug info",
" --dump-tasks: prints the task running on all CPUs if stop conditions are met (depends on !--no-aa)",
@@ -352,6 +355,7 @@ static struct timerlat_top_params
static struct option long_options[] = {
{"auto", required_argument, 0, 'a'},
{"cpus", required_argument, 0, 'c'},
+ {"cgroup", optional_argument, 0, 'C'},
{"debug", no_argument, 0, 'D'},
{"duration", required_argument, 0, 'd'},
{"event", required_argument, 0, 'e'},
@@ -376,7 +380,7 @@ static struct timerlat_top_params
/* getopt_long stores the option index here. */
int option_index = 0;

- c = getopt_long(argc, argv, "a:c:d:De:hi:np:P:qs:t::T:0:1:2:345:",
+ c = getopt_long(argc, argv, "a:c:C::d:De:hi:np:P:qs:t::T:0:1:2:345:",
long_options, &option_index);

/* detect the end of the options. */
@@ -417,6 +421,16 @@ static struct timerlat_top_params
timerlat_top_usage("\nInvalid -c cpu list\n");
params->cpus = optarg;
break;
+ case 'C':
+ params->cgroup = 1;
+ if (!optarg) {
+ /* will inherit this cgroup */
+ params->cgroup_name = NULL;
+ } else if (*optarg == '=') {
+ /* skip the = */
+ params->cgroup_name = ++optarg;
+ }
+ break;
case 'D':
config_debug = 1;
break;
@@ -694,6 +708,14 @@ int timerlat_top_main(int argc, char *argv[])
}
}

+ if (params->cgroup) {
+ retval = set_comm_cgroup("timerlat/", params->cgroup_name);
+ if (!retval) {
+ err_msg("Failed to move threads to cgroup\n");
+ goto out_free;
+ }
+ }
+
if (params->dma_latency >= 0) {
dma_latency_fd = set_cpu_dma_latency(params->dma_latency);
if (dma_latency_fd < 0) {
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 663a047f794d..bcc0a9f39cfe 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -529,3 +529,188 @@ int set_cpu_dma_latency(int32_t latency)

return fd;
}
+
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+/*
+ * find_mount - find a the mount point of a given fs
+ *
+ * Returns 0 if mount is not found, otherwise return 1 and fill mp
+ * with the mount point.
+ */
+static const int find_mount(const char *fs, char *mp, int sizeof_mp)
+{
+ char mount_point[MAX_PATH];
+ char type[100];
+ int found;
+ FILE *fp;
+
+ fp = fopen("/proc/mounts", "r");
+ if (!fp)
+ return 0;
+
+ while (fscanf(fp, "%*s %" STR(MAX_PATH) "s %99s %*s %*d %*d\n", mount_point, type) == 2) {
+ if (strcmp(type, fs) == 0) {
+ found = 1;
+ break;
+ }
+ }
+ fclose(fp);
+
+ if (!found)
+ return 0;
+
+ memset(mp, 0, sizeof_mp);
+ strncpy(mp, mount_point, sizeof_mp - 1);
+
+ debug_msg("Fs %s found at %s\n", fs, mp);
+ return 1;
+}
+
+/*
+ * get_self_cgroup - get the current thread cgroup path
+ *
+ * Parse /proc/$$/cgroup file to get the thread's cgroup. As an example of line to parse:
+ *
+ * 0::/user.slice/user-0.slice/session-3.scope'\n'
+ *
+ * This function is interested in the content after the second : and before the '\n'.
+ *
+ * Returns 1 if a string was found, 0 otherwise.
+ */
+static int get_self_cgroup(char *self_cg, int sizeof_self_cg)
+{
+ char path[MAX_PATH], *start;
+ int fd, retval;
+
+ snprintf(path, MAX_PATH, "/proc/%d/cgroup", getpid());
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ return 0;
+
+ retval = read(fd, path, MAX_PATH);
+
+ close(fd);
+
+ if (retval <= 0)
+ return 0;
+
+ start = path;
+
+ start = strstr(start, ":");
+ if (!start)
+ return 0;
+
+ /* skip ":" */
+ start++;
+
+ start = strstr(start, ":");
+ if (!start)
+ return 0;
+
+ /* skip ":" */
+ start++;
+
+ if (strlen(start) >= sizeof_self_cg)
+ return 0;
+
+ snprintf(self_cg, sizeof_self_cg, "%s", start);
+
+ /* Swap '\n' with '\0' */
+ start = strstr(self_cg, "\n");
+
+ /* there must be '\n' */
+ if (!start)
+ return 0;
+
+ /* ok, it found a string after the second : and before the \n */
+ *start = '\0';
+
+ return 1;
+}
+
+/**
+ * set_comm_cgroup - Set cgroup to threads starting with char *comm_prefix
+ *
+ * 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_comm_cgroup(const char *comm_prefix, const char *cgroup)
+{
+ char cgroup_path[MAX_PATH - strlen("/cgroup.procs")];
+ char cgroup_procs[MAX_PATH];
+ struct dirent *proc_entry;
+ DIR *procfs;
+ int retval;
+ int cg_fd;
+
+ if (strlen(comm_prefix) >= MAX_PATH) {
+ err_msg("Command prefix is too long: %d < strlen(%s)\n",
+ MAX_PATH, comm_prefix);
+ return 0;
+ }
+
+ 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;
+
+ procfs = opendir("/proc");
+ if (!procfs) {
+ err_msg("Could not open procfs\n");
+ goto out_cg;
+ }
+
+ while ((proc_entry = readdir(procfs))) {
+
+ retval = procfs_is_workload_pid(comm_prefix, proc_entry);
+ if (!retval)
+ continue;
+
+ retval = write(cg_fd, proc_entry->d_name, strlen(proc_entry->d_name));
+ if (retval < 0) {
+ err_msg("Error setting cgroup attributes for pid:%s - %s\n",
+ proc_entry->d_name, strerror(errno));
+ goto out_procfs;
+ }
+
+ debug_msg("Set cgroup attributes for pid:%s\n", proc_entry->d_name);
+ }
+
+ closedir(procfs);
+ close(cg_fd);
+ return 1;
+
+out_procfs:
+ closedir(procfs);
+out_cg:
+ close(cg_fd);
+ return 0;
+}
diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
index 90e4f52a030b..42b6f099d10a 100644
--- a/tools/tracing/rtla/src/utils.h
+++ b/tools/tracing/rtla/src/utils.h
@@ -55,6 +55,7 @@ struct sched_attr {

int parse_prio(char *arg, struct sched_attr *sched_param);
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_cpu_dma_latency(int32_t latency);

#define ns_to_usf(x) (((double)x/1000))
--
2.38.1