diff options
Diffstat (limited to 'tools/tracing/rtla/src/utils.c')
| -rw-r--r-- | tools/tracing/rtla/src/utils.c | 324 |
1 files changed, 306 insertions, 18 deletions
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c index 663a047f794d..623a38908ed5 100644 --- a/tools/tracing/rtla/src/utils.c +++ b/tools/tracing/rtla/src/utils.c @@ -3,6 +3,7 @@ * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org> */ +#define _GNU_SOURCE #include <dirent.h> #include <stdarg.h> #include <stdlib.h> @@ -88,27 +89,24 @@ void get_duration(time_t start_time, char *output, int output_size) } /* - * parse_cpu_list - parse a cpu_list filling a char vector with cpus set + * parse_cpu_set - parse a cpu_list filling cpu_set_t argument * - * Receives a cpu list, like 1-3,5 (cpus 1, 2, 3, 5), and then set the char - * in the monitored_cpus. + * Receives a cpu list, like 1-3,5 (cpus 1, 2, 3, 5), and then set + * filling cpu_set_t argument. * - * XXX: convert to a bitmask. + * Returns 1 on success, 0 otherwise. */ -int parse_cpu_list(char *cpu_list, char **monitored_cpus) +int parse_cpu_set(char *cpu_list, cpu_set_t *set) { - char *mon_cpus; const char *p; int end_cpu; int nr_cpus; int cpu; int i; - nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + CPU_ZERO(set); - mon_cpus = calloc(nr_cpus, sizeof(char)); - if (!mon_cpus) - goto err; + nr_cpus = sysconf(_SC_NPROCESSORS_CONF); for (p = cpu_list; *p; ) { cpu = atoi(p); @@ -128,12 +126,12 @@ int parse_cpu_list(char *cpu_list, char **monitored_cpus) end_cpu = cpu; if (cpu == end_cpu) { - debug_msg("cpu_list: adding cpu %d\n", cpu); - mon_cpus[cpu] = 1; + debug_msg("cpu_set: adding cpu %d\n", cpu); + CPU_SET(cpu, set); } else { for (i = cpu; i <= end_cpu; i++) { - debug_msg("cpu_list: adding cpu %d\n", i); - mon_cpus[i] = 1; + debug_msg("cpu_set: adding cpu %d\n", i); + CPU_SET(i, set); } } @@ -141,12 +139,9 @@ int parse_cpu_list(char *cpu_list, char **monitored_cpus) p++; } - *monitored_cpus = mon_cpus; - return 0; - err: - debug_msg("Error parsing the cpu list %s", cpu_list); + debug_msg("Error parsing the cpu set %s\n", cpu_list); return 1; } @@ -529,3 +524,296 @@ 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 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 + * + * 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; +} + +/** + * auto_house_keeping - Automatically move rtla out of measurement threads + * + * Try to move rtla away from the tracer, if possible. + * + * Returns 1 on success, 0 otherwise. + */ +int auto_house_keeping(cpu_set_t *monitored_cpus) +{ + cpu_set_t rtla_cpus, house_keeping_cpus; + int retval; + + /* first get the CPUs in which rtla can actually run. */ + retval = sched_getaffinity(getpid(), sizeof(rtla_cpus), &rtla_cpus); + if (retval == -1) { + debug_msg("Could not get rtla affinity, rtla might run with the threads!\n"); + return 0; + } + + /* then check if the existing setup is already good. */ + CPU_AND(&house_keeping_cpus, &rtla_cpus, monitored_cpus); + if (!CPU_COUNT(&house_keeping_cpus)) { + debug_msg("rtla and the monitored CPUs do not share CPUs."); + debug_msg("Skipping auto house-keeping\n"); + return 1; + } + + /* remove the intersection */ + CPU_XOR(&house_keeping_cpus, &rtla_cpus, monitored_cpus); + + /* get only those that rtla can run */ + CPU_AND(&house_keeping_cpus, &house_keeping_cpus, &rtla_cpus); + + /* is there any cpu left? */ + if (!CPU_COUNT(&house_keeping_cpus)) { + debug_msg("Could not find any CPU for auto house-keeping\n"); + return 0; + } + + retval = sched_setaffinity(getpid(), sizeof(house_keeping_cpus), &house_keeping_cpus); + if (retval == -1) { + debug_msg("Could not set affinity for auto house-keeping\n"); + return 0; + } + + debug_msg("rtla automatically moved to an auto house-keeping cpu set\n"); + + return 1; +} |