tools/cgclassify: add support for default systemd delegation slice/scope

Enhance the cgclassify tool to support default systemd delegation
slice/scope, if set in the cgconfig.conf's systemd setting.  Parse the
configuration file and read the systemd::delegate setting, if
any, and set it as the default systemd slice/scope in
systemd_default_cgroup. Setting it appends the slice/scope
name to the constructed default cgroup mount path.

When the user passes the relative cgroup name, its appends to the
sub-tree (delegated slice/scope) by default and if the user wishes to
create a cgroup in another subtree or cgroup root hierarchy, they need
to use the absolute path. For example:

                      cgroup_root
                     /          \
                    /            \
             systemd.slice*      cgrp1
                    |
             systemd.scope
                    |
                cgrp-d1

* default system delegation slice/scope - read from cgconfig.conf
$ sudo cgclassify -g cpu:cgrp-d1 1379 (pid)

will create the cgroup under the cpu controller hirearchy
cgroup_root:systemd_default_cgroup:cgrp-d1

and for creating a cgroup cgrp1, the user can use:
$ sudo cgclassify -g cpu:/cgrp1 1379 (pid)

or use the newly introduced -b switch to ignore the systemd slice/scope:
$ sudo cgclassify -b -g cpu:cgrp1 1379 (pid)

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>

diff --git a/src/tools/cgclassify.c b/src/tools/cgclassify.c
index 147b9dbfa2338a7f8d931c26317ad6a101d93c4f..f9f8aa888a65fa7360d38ac9c00eea067ebe7f67 100644 (file)
--- a/src/tools/cgclassify.c
+++ b/src/tools/cgclassify.c
@@ -41,6 +41,9 @@ static void usage(int status, const char *program_name)
        info("  --cancel-sticky         cgred daemon change pidlist and children tasks\n");
        info("  --sticky                        cgred daemon does not change ");
        info("pidlist and children tasks\n");
+#ifdef WITH_SYSTEMD
+       info("  -b                              Ignore default systemd delegate hierarchy\n");
+#endif
 }
 
 /*
@@ -113,6 +116,7 @@ static struct option longopts[] = {
 int main(int argc, char *argv[])
 {
        struct cgroup_group_spec *cgroup_list[CG_HIER_MAX];
+       int ignore_default_systemd_delegate_slice = 0;
        int ret = 0, i, exit_code = 0;
        int cg_specified = 0;
        int flag = 0;
@@ -126,8 +130,16 @@ int main(int argc, char *argv[])
        }
 
        memset(cgroup_list, 0, sizeof(cgroup_list));
+#ifdef WITH_SYSTEMD
+       while ((c = getopt_long(argc, argv, "+g:shb", longopts, NULL)) > 0) {
+               switch (c) {
+               case 'b':
+                       ignore_default_systemd_delegate_slice = 1;
+                       break;
+#else
        while ((c = getopt_long(argc, argv, "+g:sh", longopts, NULL)) > 0) {
                switch (c) {
+#endif
                case 'h':
                        usage(0, argv[0]);
                        exit(0);
@@ -160,6 +172,10 @@ int main(int argc, char *argv[])
                return ret;
        }
 
+       /* this is false always for disable-systemd */
+       if (!ignore_default_systemd_delegate_slice)
+               cgroup_set_default_systemd_cgroup();
+
        for (i = optind; i < argc; i++) {
                pid = (pid_t) strtol(argv[i], &endptr, 10);
                if (endptr[0] != '\0') {