diff options
Diffstat (limited to 'tools/tracing/rtla/src/utils.c')
| -rw-r--r-- | tools/tracing/rtla/src/utils.c | 185 |
1 files changed, 185 insertions, 0 deletions
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; +} |