Re: [libvirt] [PATCH 3/7] Make cgroups a little more efficient

* src/cgroup.c: Detect the mount location of every controller at time a virCgroupPtr is created. Detect current process' placement within group to avoid assuming it is in the root. Pass controller ID into SetValueStr/GetValueStr to enable much duplicated code to be eliminated

+/* + * Process /proc/mounts figuring out what controllers are + * mounted and where + */ +static int virCgroupDetectMounts(virCgroupPtr group) { + int i; FILE *mounts = NULL; struct mntent entry; char buf[CGROUP_MAX_VAL]; - virCgroupPtr root = NULL; - - if (VIR_ALLOC(root) != 0) - return NULL; mounts = fopen("/proc/mounts", "r"); if (mounts == NULL) { - DEBUG0("Unable to open /proc/mounts: %m"); - goto err; + VIR_ERROR0("Unable to open /proc/mounts"); + return -ENOENT; } while (getmntent_r(mounts, &entry, buf, sizeof(buf)) != NULL) { - if (STREQ(entry.mnt_type, "cgroup") && - (strstr(entry.mnt_opts, controller))) { - root->path = strdup(entry.mnt_dir); - break; - } - } - - DEBUG("Mount for %s is %s\n", controller, root->path);

+ if (STRNEQ(entry.mnt_type, "cgroup")) + continue; - if (root->path == NULL) { - DEBUG0("Did not find cgroup mount"); - goto err; + for (i = 0 ; i < VIR_CGROUP_CONTROLLER_LAST ; i++) { + const char *typestr = virCgroupControllerTypeToString(i); + int typelen = strlen(typestr); + char *tmp = entry.mnt_opts; + while (tmp) { + char *next = strchr(tmp, ','); + int len; + if (next) { + len = next-tmp; + next++; + } else { + len = strlen(tmp); + } + if (typelen == len && STREQLEN(typestr, tmp, len) && + !(group->controllers[i].mountPoint = strdup(entry.mnt_dir))) + goto no_memory; + tmp = next; + } + } } fclose(mounts); - return root; -err: - if (mounts != NULL) - fclose(mounts); - virCgroupFree(&root); + return 0; - return NULL; +no_memory: + if (mounts) + fclose(mounts); + return -ENOMEM; }

+ while (fgets(line, sizeof(line), mapping) != NULL) { + char *controllers = strchr(line, ':'); + char *path = controllers ? strchr(controllers+1, ':') : NULL; + char *nl = path ? strchr(path, '\n') : NULL; + + if (!controllers || !path) + continue;

- if (sscanf(key, "%a[^.]", &controller) != 1) - return -EINVAL;