cgroup.c

   1 /*
   2  * Code related to setting up a blkio cgroup
   3  */
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <mntent.h>
   7 #include <sys/stat.h>
   8 #include <sys/types.h>
   9 #include "fio.h"
  10 #include "flist.h"
  11 #include "cgroup.h"
  12 #include "smalloc.h"
  13
  14 static struct fio_mutex *lock;
  15
  16 struct cgroup_member {
  17         struct flist_head list;
  18         char *root;
  19         unsigned int cgroup_nodelete;
  20 };
  21
  22 static char *find_cgroup_mnt(struct thread_data *td)
  23 {
  24         char *mntpoint = NULL;
  25         struct mntent *mnt, dummy;
  26         char buf[256] = {0};
  27         FILE *f;
  28
  29         f = setmntent("/proc/mounts", "r");
  30         if (!f) {
  31                 td_verror(td, errno, "setmntent /proc/mounts");
  32                 return NULL;
  33         }
  34
  35         while ((mnt = getmntent_r(f, &dummy, buf, sizeof(buf))) != NULL) {
  36                 if (!strcmp(mnt->mnt_type, "cgroup") &&
  37                     strstr(mnt->mnt_opts, "blkio"))
  38                         break;
  39         }
  40
  41         if (mnt)
  42                 mntpoint = smalloc_strdup(mnt->mnt_dir);
  43         else
  44                 log_err("fio: cgroup blkio does not appear to be mounted\n");
  45
  46         endmntent(f);
  47         return mntpoint;
  48 }
  49
  50 static void add_cgroup(struct thread_data *td, const char *name,
  51                         struct flist_head *clist)
  52 {
  53         struct cgroup_member *cm;
  54
  55         cm = smalloc(sizeof(*cm));
  56         INIT_FLIST_HEAD(&cm->list);
  57         cm->root = smalloc_strdup(name);
  58         if (td->o.cgroup_nodelete)
  59                 cm->cgroup_nodelete = 1;
  60         fio_mutex_down(lock);
  61         flist_add_tail(&cm->list, clist);
  62         fio_mutex_up(lock);
  63 }
  64
  65 void cgroup_kill(struct flist_head *clist)
  66 {
  67         struct flist_head *n, *tmp;
  68         struct cgroup_member *cm;
  69
  70         fio_mutex_down(lock);
  71
  72         flist_for_each_safe(n, tmp, clist) {
  73                 cm = flist_entry(n, struct cgroup_member, list);
  74                 if (!cm->cgroup_nodelete)
  75                         rmdir(cm->root);
  76                 flist_del(&cm->list);
  77                 sfree(cm->root);
  78                 sfree(cm);
  79         }
  80
  81         fio_mutex_up(lock);
  82 }
  83
  84 static char *get_cgroup_root(struct thread_data *td, char *mnt)
  85 {
  86         char *str = malloc(64);
  87
  88         if (td->o.cgroup)
  89                 sprintf(str, "%s%s%s", mnt, FIO_OS_PATH_SEPARATOR, td->o.cgroup);
  90         else
  91                 sprintf(str, "%s%s%s", mnt, FIO_OS_PATH_SEPARATOR, td->o.name);
  92
  93         return str;
  94 }
  95
  96 static int write_int_to_file(struct thread_data *td, const char *path,
  97                              const char *filename, unsigned int val,
  98                              const char *onerr)
  99 {
 100         char tmp[256];
 101         FILE *f;
 102
 103         sprintf(tmp, "%s%s%s", path, FIO_OS_PATH_SEPARATOR, filename);
 104         f = fopen(tmp, "w");
 105         if (!f) {
 106                 td_verror(td, errno, onerr);
 107                 return 1;
 108         }
 109
 110         fprintf(f, "%u", val);
 111         fclose(f);
 112         return 0;
 113
 114 }
 115
 116 static int cgroup_write_pid(struct thread_data *td, const char *root)
 117 {
 118         unsigned int val = td->pid;
 119
 120         return write_int_to_file(td, root, "tasks", val, "cgroup write pid");
 121 }
 122
 123 /*
 124  * Move pid to root class
 125  */
 126 static int cgroup_del_pid(struct thread_data *td, char *mnt)
 127 {
 128         return cgroup_write_pid(td, mnt);
 129 }
 130
 131 int cgroup_setup(struct thread_data *td, struct flist_head *clist, char **mnt)
 132 {
 133         char *root;
 134
 135         if (!*mnt) {
 136                 *mnt = find_cgroup_mnt(td);
 137                 if (!*mnt)
 138                         return 1;
 139         }
 140
 141         /*
 142          * Create container, if it doesn't exist
 143          */
 144         root = get_cgroup_root(td, *mnt);
 145         if (mkdir(root, 0755) < 0) {
 146                 int __e = errno;
 147
 148                 if (__e != EEXIST) {
 149                         td_verror(td, __e, "cgroup mkdir");
 150                         log_err("fio: path %s\n", root);
 151                         goto err;
 152                 }
 153         } else
 154                 add_cgroup(td, root, clist);
 155
 156         if (td->o.cgroup_weight) {
 157                 if (write_int_to_file(td, root, "blkio.weight",
 158                                         td->o.cgroup_weight,
 159                                         "cgroup open weight"))
 160                         goto err;
 161         }
 162
 163         if (!cgroup_write_pid(td, root)) {
 164                 free(root);
 165                 return 0;
 166         }
 167
 168 err:
 169         free(root);
 170         return 1;
 171 }
 172
 173 void cgroup_shutdown(struct thread_data *td, char **mnt)
 174 {
 175         if (*mnt == NULL)
 176                 return;
 177         if (!td->o.cgroup_weight && !td->o.cgroup)
 178                 return;
 179
 180         cgroup_del_pid(td, *mnt);
 181 }
 182
 183 static void fio_init cgroup_init(void)
 184 {
 185         lock = fio_mutex_init(1);
 186 }
 187
 188 static void fio_exit cgroup_exit(void)
 189 {
 190         fio_mutex_remove(lock);
 191 }