Merge pull request #1063 from poettering/dbus-interface-from-type

cgls/cgtop: a variety of modernizations

24 files changed, 375 insertions, 276 deletions

diff --git a/man/systemd-cgtop.xml b/man/systemd-cgtop.xml
index d4b041a1f9..e4bc22f278 100644
--- a/man/systemd-cgtop.xml
+++ b/man/systemd-cgtop.xml
@@ -1,4 +1,4 @@
-<?xml version='1.0'?> <!--*-nxml-*-->
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 
@@ -64,10 +64,10 @@
     regular intervals (by default every 1s), similar in style to
     <citerefentry project='man-pages'><refentrytitle>top</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 
-    <para>If <command>systemd-cgtop</command> is not connected to a tty, no
-    column headers are printed and the default is to only run one iteration.
-    The <varname>--iterations</varname> argument, if given, is still honored.
-    This mode is suitable for scripting.</para>
+    <para>If <command>systemd-cgtop</command> is not connected to a
+    tty, no column headers are printed and the default is to only run
+    one iteration.  The <varname>--iterations=</varname> argument, if
+    given, is honored. This mode is suitable for scripting.</para>
 
     <para>Resource usage is only accounted for control groups in the
     relevant hierarchy, i.e. CPU usage is only accounted for control
@@ -104,6 +104,7 @@
     <variablelist>
       <varlistentry>
         <term><option>-p</option></term>
+        <term><option>--order=path</option></term>
 
         <listitem><para>Order by control group
         path name.</para></listitem>
@@ -111,25 +112,28 @@
 
       <varlistentry>
         <term><option>-t</option></term>
+        <term><option>--order=tasks</option></term>
 
-        <listitem><para>Order by number of tasks in control group
-        (i.e. threads and processes).</para></listitem>
+        <listitem><para>Order by number of processes in control group.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><option>-c</option></term>
+        <term><option>--order=cpu</option></term>
 
         <listitem><para>Order by CPU load.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><option>-m</option></term>
+        <term><option>--order=memory</option></term>
 
         <listitem><para>Order by memory usage.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><option>-i</option></term>
+        <term><option>--order=io</option></term>
 
         <listitem><para>Order by disk I/O load.</para></listitem>
       </varlistentry>
@@ -140,7 +144,7 @@
 
         <listitem><para>Run in "batch" mode: do not accept input and
         run until the iteration limit set with
-        <option>--iterations</option> is exhausted or until killed.
+        <option>--iterations=</option> is exhausted or until killed.
         This mode could be useful for sending output from
         <command>systemd-cgtop</command> to other programs or to a
         file.</para></listitem>
@@ -156,6 +160,15 @@
       </varlistentry>
 
       <varlistentry>
+        <term><option>--cpu=percentage</option></term>
+        <term><option>--cpu=time</option></term>
+
+        <listitem><para>Controls whether the CPU usage is shown as
+        percentage or time. By default the CPU usage is shown as
+        percentage.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>-n</option></term>
         <term><option>--iterations=</option></term>
 
diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index 3d8d5d7568..afc6a6eb24 100644
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -37,6 +37,14 @@ usec_t now(clockid_t clock_id) {
         return timespec_load(&ts);
 }
 
+nsec_t now_nsec(clockid_t clock_id) {
+        struct timespec ts;
+
+        assert_se(clock_gettime(clock_id, &ts) == 0);
+
+        return timespec_load_nsec(&ts);
+}
+
 dual_timestamp* dual_timestamp_get(dual_timestamp *ts) {
         assert(ts);
 
@@ -130,6 +138,18 @@ usec_t timespec_load(const struct timespec *ts) {
                 (usec_t) ts->tv_nsec / NSEC_PER_USEC;
 }
 
+nsec_t timespec_load_nsec(const struct timespec *ts) {
+        assert(ts);
+
+        if (ts->tv_sec == (time_t) -1 &&
+            ts->tv_nsec == (long) -1)
+                return NSEC_INFINITY;
+
+        return
+                (nsec_t) ts->tv_sec * NSEC_PER_SEC +
+                (nsec_t) ts->tv_nsec;
+}
+
 struct timespec *timespec_store(struct timespec *ts, usec_t u)  {
         assert(ts);
 
diff --git a/src/basic/time-util.h b/src/basic/time-util.h
index 03a47f310d..de881e8fe1 100644
--- a/src/basic/time-util.h
+++ b/src/basic/time-util.h
@@ -70,6 +70,7 @@ typedef struct dual_timestamp {
 #define DUAL_TIMESTAMP_NULL ((struct dual_timestamp) { 0ULL, 0ULL })
 
 usec_t now(clockid_t clock);
+nsec_t now_nsec(clockid_t clock);
 
 dual_timestamp* dual_timestamp_get(dual_timestamp *ts);
 dual_timestamp* dual_timestamp_from_realtime(dual_timestamp *ts, usec_t u);
@@ -87,6 +88,8 @@ struct timespec *timespec_store(struct timespec *ts, usec_t u);
 usec_t timeval_load(const struct timeval *tv) _pure_;
 struct timeval *timeval_store(struct timeval *tv, usec_t u);
 
+nsec_t timespec_load_nsec(const struct timespec *ts) _pure_;
+
 char *format_timestamp(char *buf, size_t l, usec_t t);
 char *format_timestamp_utc(char *buf, size_t l, usec_t t);
 char *format_timestamp_us(char *buf, size_t l, usec_t t);
diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c
index fa530da456..8742ee757f 100644
--- a/src/basic/unit-name.c
+++ b/src/basic/unit-name.c
@@ -586,6 +586,42 @@ int unit_name_from_dbus_path(const char *path, char **name) {
         return 0;
 }
 
+const char* unit_dbus_interface_from_type(UnitType t) {
+
+        static const char *const table[_UNIT_TYPE_MAX] = {
+                [UNIT_SERVICE] = "org.freedesktop.systemd1.Service",
+                [UNIT_SOCKET] = "org.freedesktop.systemd1.Socket",
+                [UNIT_BUSNAME] = "org.freedesktop.systemd1.BusName",
+                [UNIT_TARGET] = "org.freedesktop.systemd1.Target",
+                [UNIT_SNAPSHOT] = "org.freedesktop.systemd1.Snapshot",
+                [UNIT_DEVICE] = "org.freedesktop.systemd1.Device",
+                [UNIT_MOUNT] = "org.freedesktop.systemd1.Mount",
+                [UNIT_AUTOMOUNT] = "org.freedesktop.systemd1.Automount",
+                [UNIT_SWAP] = "org.freedesktop.systemd1.Swap",
+                [UNIT_TIMER] = "org.freedesktop.systemd1.Timer",
+                [UNIT_PATH] = "org.freedesktop.systemd1.Path",
+                [UNIT_SLICE] = "org.freedesktop.systemd1.Slice",
+                [UNIT_SCOPE] = "org.freedesktop.systemd1.Scope",
+        };
+
+        if (t < 0)
+                return NULL;
+        if (t >= _UNIT_TYPE_MAX)
+                return NULL;
+
+        return table[t];
+}
+
+const char *unit_dbus_interface_from_name(const char *name) {
+        UnitType t;
+
+        t = unit_name_to_type(name);
+        if (t < 0)
+                return NULL;
+
+        return unit_dbus_interface_from_type(t);
+}
+
 static char *do_escape_mangle(const char *f, UnitNameMangle allow_globs, char *t) {
         const char *valid_chars;
 
@@ -787,7 +823,7 @@ static const char* const unit_type_table[_UNIT_TYPE_MAX] = {
         [UNIT_TIMER] = "timer",
         [UNIT_PATH] = "path",
         [UNIT_SLICE] = "slice",
-        [UNIT_SCOPE] = "scope"
+        [UNIT_SCOPE] = "scope",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(unit_type, UnitType);
diff --git a/src/basic/unit-name.h b/src/basic/unit-name.h
index b2043d0870..28b3a555f3 100644
--- a/src/basic/unit-name.h
+++ b/src/basic/unit-name.h
@@ -152,6 +152,9 @@ int unit_name_to_path(const char *name, char **ret);
 char *unit_dbus_path_from_name(const char *name);
 int unit_name_from_dbus_path(const char *path, char **name);
 
+const char* unit_dbus_interface_from_type(UnitType t);
+const char *unit_dbus_interface_from_name(const char *name);
+
 typedef enum UnitNameMangle {
         UNIT_NAME_NOGLOB,
         UNIT_NAME_GLOB,
diff --git a/src/cgls/cgls.c b/src/cgls/cgls.c
index b8d1d2ccaf..fae9398aa5 100644
--- a/src/cgls/cgls.c
+++ b/src/cgls/cgls.c
@@ -54,7 +54,7 @@ static void help(void) {
                "  -a --all            Show all groups, including empty\n"
                "  -l --full           Do not ellipsize output\n"
                "  -k                  Include kernel threads in output\n"
-               "  -M --machine        Show container\n"
+               "  -M --machine=       Show container\n"
                , program_invocation_short_name);
 }
 
@@ -123,146 +123,158 @@ static int parse_argv(int argc, char *argv[]) {
         return 1;
 }
 
-int main(int argc, char *argv[]) {
-        int r = 0, retval = EXIT_FAILURE;
-        int output_flags;
-        _cleanup_free_ char *root = NULL;
+static int get_cgroup_root(char **ret) {
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
+        _cleanup_free_ char *unit = NULL, *path = NULL;
+        const char *m;
+        int r;
+
+        if (!arg_machine) {
+                r = cg_get_root_path(ret);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to get root control group path: %m");
+
+                return 0;
+        }
+
+        m = strjoina("/run/systemd/machines/", arg_machine);
+        r = parse_env_file(m, NEWLINE, "SCOPE", &unit, NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to load machine data: %m");
+
+        path = unit_dbus_path_from_name(unit);
+        if (!path)
+                return log_oom();
+
+        r = bus_open_transport(BUS_TRANSPORT_LOCAL, NULL, false, &bus);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create bus connection: %m");
+
+        r = sd_bus_get_property_string(
+                        bus,
+                        "org.freedesktop.systemd1",
+                        path,
+                        unit_dbus_interface_from_name(unit),
+                        "ControlGroup",
+                        &error,
+                        ret);
+        if (r < 0)
+                return log_error_errno(r, "Failed to query unit control group path: %m");
+
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        int r, output_flags;
 
         log_parse_environment();
         log_open();
 
         r = parse_argv(argc, argv);
-        if (r < 0)
+        if (r <= 0)
                 goto finish;
-        else if (r == 0) {
-                retval = EXIT_SUCCESS;
-                goto finish;
-        }
 
         if (!arg_no_pager) {
                 r = pager_open(false);
-                if (r > 0) {
-                        if (arg_full == -1)
-                                arg_full = true;
-                }
+                if (r > 0 && arg_full < 0)
+                        arg_full = true;
         }
 
         output_flags =
                 arg_all * OUTPUT_SHOW_ALL |
                 (arg_full > 0) * OUTPUT_FULL_WIDTH;
 
-        r = bus_open_transport(BUS_TRANSPORT_LOCAL, NULL, false, &bus);
-        if (r < 0) {
-                log_error_errno(r, "Failed to create bus connection: %m");
-                goto finish;
-        }
-
         if (optind < argc) {
+                _cleanup_free_ char *root = NULL;
                 int i;
 
+                r = get_cgroup_root(&root);
+                if (r < 0)
+                        goto finish;
+
                 for (i = optind; i < argc; i++) {
                         int q;
 
-                        fprintf(stdout, "%s:\n", argv[i]);
-                        fflush(stdout);
-
-                        if (arg_machine)
-                                root = strjoin("machine/", arg_machine, "/", argv[i], NULL);
-                        else
-                                root = strdup(argv[i]);
-                        if (!root)
-                                return log_oom();
-
-                        q = show_cgroup_by_path(root, NULL, 0,
-                                                arg_kernel_threads, output_flags);
-                        if (q < 0)
-                                r = q;
-                }
+                        if (path_startswith(argv[i], "/sys/fs/cgroup")) {
 
-        } else {
-                _cleanup_free_ char *p;
+                                printf("Directory %s:\n", argv[i]);
+                                fflush(stdout);
 
-                p = get_current_dir_name();
-                if (!p) {
-                        log_error_errno(errno, "Cannot determine current working directory: %m");
-                        goto finish;
-                }
+                                q = show_cgroup_by_path(argv[i], NULL, 0, arg_kernel_threads, output_flags);
+                        } else {
+                                _cleanup_free_ char *c = NULL, *p = NULL, *j = NULL;
+                                const char *controller, *path;
 
-                if (path_startswith(p, "/sys/fs/cgroup") && !arg_machine) {
-                        printf("Working Directory %s:\n", p);
-                        r = show_cgroup_by_path(p, NULL, 0,
-                                                arg_kernel_threads, output_flags);
-                } else {
-                        if (arg_machine) {
-                                char *m;
-                                const char *cgroup;
-                                _cleanup_free_ char *unit = NULL;
-                                _cleanup_free_ char *path = NULL;
-                                _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-                                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
-
-                                m = strjoina("/run/systemd/machines/", arg_machine);
-                                r = parse_env_file(m, NEWLINE, "SCOPE", &unit, NULL);
+                                r = cg_split_spec(argv[i], &c, &p);
                                 if (r < 0) {
-                                        log_error_errno(r, "Failed to get machine path: %m");
+                                        log_error_errno(r, "Failed to split argument %s: %m", argv[i]);
                                         goto finish;
                                 }
 
-                                path = unit_dbus_path_from_name(unit);
-                                if (!path) {
-                                        log_oom();
-                                        goto finish;
-                                }
+                                controller = c ?: SYSTEMD_CGROUP_CONTROLLER;
+                                if (p) {
+                                        j = strjoin(root, "/", p, NULL);
+                                        if (!j) {
+                                                r = log_oom();
+                                                goto finish;
+                                        }
 
-                                r = sd_bus_get_property(
-                                                bus,
-                                                "org.freedesktop.systemd1",
-                                                path,
-                                                endswith(unit, ".scope") ? "org.freedesktop.systemd1.Scope" : "org.freedesktop.systemd1.Service",
-                                                "ControlGroup",
-                                                &error,
-                                                &reply,
-                                                "s");
+                                        path_kill_slashes(j);
+                                        path = j;
+                                } else
+                                        path = root;
 
-                                if (r < 0) {
-                                        log_error("Failed to query ControlGroup: %s", bus_error_message(&error, -r));
-                                        goto finish;
-                                }
+                                printf("Controller %s; control group %s:\n", controller, path);
+                                fflush(stdout);
 
-                                r = sd_bus_message_read(reply, "s", &cgroup);
-                                if (r < 0) {
-                                        bus_log_parse_error(r);
-                                        goto finish;
-                                }
+                                q = show_cgroup(controller, path, NULL, 0, arg_kernel_threads, output_flags);
+                        }
 
-                                root = strdup(cgroup);
-                                if (!root) {
-                                        log_oom();
-                                        goto finish;
-                                }
+                        if (q < 0)
+                                r = q;
+                }
+
+        } else {
+                bool done = false;
 
-                        } else
-                                r = cg_get_root_path(&root);
-                        if (r < 0) {
-                                log_error_errno(r, "Failed to get %s path: %m",
-                                                arg_machine ? "machine" : "root");
+                if (!arg_machine)  {
+                        _cleanup_free_ char *cwd = NULL;
+
+                        cwd = get_current_dir_name();
+                        if (!cwd) {
+                                r = log_error_errno(errno, "Cannot determine current working directory: %m");
                                 goto finish;
                         }
 
-                        r = show_cgroup(SYSTEMD_CGROUP_CONTROLLER, root, NULL, 0,
-                                        arg_kernel_threads, output_flags);
+                        if (path_startswith(cwd, "/sys/fs/cgroup")) {
+                                printf("Working directory %s:\n", cwd);
+                                fflush(stdout);
+
+                                r = show_cgroup_by_path(cwd, NULL, 0, arg_kernel_threads, output_flags);
+                                done = true;
+                        }
+                }
+
+                if (!done) {
+                        _cleanup_free_ char *root = NULL;
+
+                        r = get_cgroup_root(&root);
+                        if (r < 0)
+                                goto finish;
+
+                        printf("Control group %s:\n", root);
+                        fflush(stdout);
+
+                        r = show_cgroup(SYSTEMD_CGROUP_CONTROLLER, root, NULL, 0, arg_kernel_threads, output_flags);
                 }
         }
 
-        if (r < 0) {
-                log_error_errno(r, "Failed to list cgroup tree %s: %m", root);
-                retval = EXIT_FAILURE;
-        } else
-                retval = EXIT_SUCCESS;
+        if (r < 0)
+                log_error_errno(r, "Failed to list cgroup tree: %m");
 
 finish:
         pager_close();
 
-        return retval;
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }
diff --git a/src/cgtop/cgtop.c b/src/cgtop/cgtop.c
index f953c9e624..26b104f111 100644
--- a/src/cgtop/cgtop.c
+++ b/src/cgtop/cgtop.c
@@ -19,7 +19,6 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#define __STDC_FORMAT_MACROS
 #include <errno.h>
 #include <string.h>
 #include <stdlib.h>
@@ -48,20 +47,20 @@ typedef struct Group {
         unsigned n_tasks;
 
         unsigned cpu_iteration;
-        uint64_t cpu_usage;
-        struct timespec cpu_timestamp;
+        nsec_t cpu_usage;
+        nsec_t cpu_timestamp;
         double cpu_fraction;
 
         uint64_t memory;
 
         unsigned io_iteration;
         uint64_t io_input, io_output;
-        struct timespec io_timestamp;
+        nsec_t io_timestamp;
         uint64_t io_input_bps, io_output_bps;
 } Group;
 
 static unsigned arg_depth = 3;
-static unsigned arg_iterations = (unsigned)-1;
+static unsigned arg_iterations = (unsigned) -1;
 static bool arg_batch = false;
 static bool arg_raw = false;
 static usec_t arg_delay = 1*USEC_PER_SEC;
@@ -111,9 +110,6 @@ static const char *maybe_format_bytes(char *buf, size_t l, bool is_valid, off_t
 static int process(const char *controller, const char *path, Hashmap *a, Hashmap *b, unsigned iteration) {
         Group *g;
         int r;
-        FILE *f = NULL;
-        pid_t pid;
-        unsigned n;
 
         assert(controller);
         assert(path);
@@ -142,84 +138,81 @@ static int process(const char *controller, const char *path, Hashmap *a, Hashmap
                         r = hashmap_move_one(a, b, path);
                         if (r < 0)
                                 return r;
+
                         g->cpu_valid = g->memory_valid = g->io_valid = g->n_tasks_valid = false;
                 }
         }
 
-        /* Regardless which controller, let's find the maximum number
-         * of processes in any of it */
+        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {
+                _cleanup_fclose_ FILE *f = NULL;
+                pid_t pid;
 
-        r = cg_enumerate_processes(controller, path, &f);
-        if (r < 0)
-                return r;
+                r = cg_enumerate_processes(controller, path, &f);
+                if (r == -ENOENT)
+                        return 0;
+                if (r < 0)
+                        return r;
 
-        n = 0;
-        while (cg_read_pid(f, &pid) > 0)
-                n++;
-        fclose(f);
+                g->n_tasks = 0;
+                while (cg_read_pid(f, &pid) > 0)
+                        g->n_tasks++;
 
-        if (n > 0) {
-                if (g->n_tasks_valid)
-                        g->n_tasks = MAX(g->n_tasks, n);
-                else
-                        g->n_tasks = n;
+                if (g->n_tasks > 0)
+                        g->n_tasks_valid = true;
 
-                g->n_tasks_valid = true;
-        }
-
-        if (streq(controller, "cpuacct")) {
+        } else if (streq(controller, "cpuacct")) {
+                _cleanup_free_ char *p = NULL, *v = NULL;
                 uint64_t new_usage;
-                char *p, *v;
-                struct timespec ts;
+                nsec_t timestamp;
 
                 r = cg_get_path(controller, path, "cpuacct.usage", &p);
                 if (r < 0)
                         return r;
 
                 r = read_one_line_file(p, &v);
-                free(p);
+                if (r == -ENOENT)
+                        return 0;
                 if (r < 0)
                         return r;
 
                 r = safe_atou64(v, &new_usage);
-                free(v);
                 if (r < 0)
                         return r;
 
-                assert_se(clock_gettime(CLOCK_MONOTONIC, &ts) == 0);
+                timestamp = now_nsec(CLOCK_MONOTONIC);
 
-                if (g->cpu_iteration == iteration - 1) {
-                        uint64_t x, y;
+                if (g->cpu_iteration == iteration - 1 &&
+                    (nsec_t) new_usage > g->cpu_usage) {
 
-                        x = ((uint64_t) ts.tv_sec * 1000000000ULL + (uint64_t) ts.tv_nsec) -
-                                ((uint64_t) g->cpu_timestamp.tv_sec * 1000000000ULL + (uint64_t) g->cpu_timestamp.tv_nsec);
+                        nsec_t x, y;
 
-                        y = new_usage - g->cpu_usage;
+                        x = timestamp - g->cpu_timestamp;
+                        if (x < 1)
+                                x = 1;
 
-                        if (y > 0) {
-                                g->cpu_fraction = (double) y / (double) x;
-                                g->cpu_valid = true;
-                        }
+                        y = (nsec_t) new_usage - g->cpu_usage;
+                        g->cpu_fraction = (double) y / (double) x;
+                        g->cpu_valid = true;
                 }
 
-                g->cpu_usage = new_usage;
-                g->cpu_timestamp = ts;
+                g->cpu_usage = (nsec_t) new_usage;
+                g->cpu_timestamp = timestamp;
                 g->cpu_iteration = iteration;
 
         } else if (streq(controller, "memory")) {
-                char *p, *v;
+                _cleanup_free_ char *p = NULL, *v = NULL;
 
                 r = cg_get_path(controller, path, "memory.usage_in_bytes", &p);
                 if (r < 0)
                         return r;
 
                 r = read_one_line_file(p, &v);
-                free(p);
+                if (r == -ENOENT)
+                        return 0;
                 if (r < 0)
                         return r;
 
                 r = safe_atou64(v, &g->memory);
-                free(v);
                 if (r < 0)
                         return r;
 
@@ -227,19 +220,21 @@ static int process(const char *controller, const char *path, Hashmap *a, Hashmap
                         g->memory_valid = true;
 
         } else if (streq(controller, "blkio")) {
-                char *p;
+                _cleanup_fclose_ FILE *f = NULL;
+                _cleanup_free_ char *p = NULL;
                 uint64_t wr = 0, rd = 0;
-                struct timespec ts;
+                nsec_t timestamp;
 
                 r = cg_get_path(controller, path, "blkio.io_service_bytes", &p);
                 if (r < 0)
                         return r;
 
                 f = fopen(p, "re");
-                free(p);
-
-                if (!f)
+                if (!f) {
+                        if (errno == ENOENT)
+                                return 0;
                         return -errno;
+                }
 
                 for (;;) {
                         char line[LINE_MAX], *l;
@@ -269,20 +264,26 @@ static int process(const char *controller, const char *path, Hashmap *a, Hashmap
                         *q += k;
                 }
 
-                fclose(f);
-
-                assert_se(clock_gettime(CLOCK_MONOTONIC, &ts) == 0);
+                timestamp = now_nsec(CLOCK_MONOTONIC);
 
                 if (g->io_iteration == iteration - 1) {
                         uint64_t x, yr, yw;
 
-                        x = ((uint64_t) ts.tv_sec * 1000000000ULL + (uint64_t) ts.tv_nsec) -
-                                ((uint64_t) g->io_timestamp.tv_sec * 1000000000ULL + (uint64_t) g->io_timestamp.tv_nsec);
+                        x = (uint64_t) (timestamp - g->io_timestamp);
+                        if (x < 1)
+                                x = 1;
 
-                        yr = rd - g->io_input;
-                        yw = wr - g->io_output;
+                        if (rd > g->io_input)
+                                yr = rd - g->io_input;
+                        else
+                                yr = 0;
+
+                        if (wr > g->io_output)
+                                yw = wr - g->io_output;
+                        else
+                                yw = 0;
 
-                        if (g->io_input > 0 || g->io_output > 0) {
+                        if (yr > 0 || yw > 0) {
                                 g->io_input_bps = (yr * 1000000000ULL) / x;
                                 g->io_output_bps = (yw * 1000000000ULL) / x;
                                 g->io_valid = true;
@@ -291,7 +292,7 @@ static int process(const char *controller, const char *path, Hashmap *a, Hashmap
 
                 g->io_input = rd;
                 g->io_output = wr;
-                g->io_timestamp = ts;
+                g->io_timestamp = timestamp;
                 g->io_iteration = iteration;
         }
 
@@ -306,7 +307,7 @@ static int refresh_one(
                 unsigned iteration,
                 unsigned depth) {
 
-        DIR *d = NULL;
+        _cleanup_closedir_ DIR *d = NULL;
         int r;
 
         assert(controller);
@@ -321,41 +322,29 @@ static int refresh_one(
                 return r;
 
         r = cg_enumerate_subgroups(controller, path, &d);
-        if (r < 0) {
-                if (r == -ENOENT)
-                        return 0;
-
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
                 return r;
-        }
 
         for (;;) {
-                char *fn, *p;
+                _cleanup_free_ char *fn = NULL, *p = NULL;
 
                 r = cg_read_subgroup(d, &fn);
                 if (r <= 0)
-                        goto finish;
+                        return r;
 
                 p = strjoin(path, "/", fn, NULL);
-                free(fn);
-
-                if (!p) {
-                        r = -ENOMEM;
-                        goto finish;
-                }
+                if (!p)
+                        return -ENOMEM;
 
                 path_kill_slashes(p);
 
                 r = refresh_one(controller, p, a, b, iteration, depth + 1);
-                free(p);
-
                 if (r < 0)
-                        goto finish;
+                        return r;
         }
 
-finish:
-        if (d)
-                closedir(d);
-
         return r;
 }
 
@@ -364,35 +353,43 @@ static int refresh(Hashmap *a, Hashmap *b, unsigned iteration) {
 
         assert(a);
 
-        r = refresh_one("name=systemd", "/", a, b, iteration, 0);
+        r = refresh_one(SYSTEMD_CGROUP_CONTROLLER, "/", a, b, iteration, 0);
         if (r < 0)
-                if (r != -ENOENT)
-                    return r;
+                return r;
         r = refresh_one("cpuacct", "/", a, b, iteration, 0);
         if (r < 0)
-                if (r != -ENOENT)
-                    return r;
+                return r;
         r = refresh_one("memory", "/", a, b, iteration, 0);
         if (r < 0)
-                if (r != -ENOENT)
-                    return r;
-
+                return r;
         r = refresh_one("blkio", "/", a, b, iteration, 0);
         if (r < 0)
-                if (r != -ENOENT)
-                    return r;
+                return r;
+
         return 0;
 }
 
 static int group_compare(const void*a, const void *b) {
         const Group *x = *(Group**)a, *y = *(Group**)b;
 
-        if (path_startswith(y->path, x->path))
-                return -1;
-        if (path_startswith(x->path, y->path))
-                return 1;
+        if (arg_order != ORDER_TASKS) {
+                /* Let's make sure that the parent is always before
+                 * the child. Except when ordering by tasks, since
+                 * that is actually not accumulative for all
+                 * children. */
+
+                if (path_startswith(y->path, x->path))
+                        return -1;
+                if (path_startswith(x->path, y->path))
+                        return 1;
+        }
+
+        switch (arg_order) {
+
+        case ORDER_PATH:
+                break;
 
-        if (arg_order == ORDER_CPU) {
+        case ORDER_CPU:
                 if (arg_cpu_type == CPU_PERCENT) {
                         if (x->cpu_valid && y->cpu_valid) {
                                 if (x->cpu_fraction > y->cpu_fraction)
@@ -409,10 +406,10 @@ static int group_compare(const void*a, const void *b) {
                         else if (x->cpu_usage < y->cpu_usage)
                                 return 1;
                 }
-        }
 
-        if (arg_order == ORDER_TASKS) {
+                break;
 
+        case ORDER_TASKS:
                 if (x->n_tasks_valid && y->n_tasks_valid) {
                         if (x->n_tasks > y->n_tasks)
                                 return -1;
@@ -422,9 +419,10 @@ static int group_compare(const void*a, const void *b) {
                         return -1;
                 else if (y->n_tasks_valid)
                         return 1;
-        }
 
-        if (arg_order == ORDER_MEMORY) {
+                break;
+
+        case ORDER_MEMORY:
                 if (x->memory_valid && y->memory_valid) {
                         if (x->memory > y->memory)
                                 return -1;
@@ -434,9 +432,10 @@ static int group_compare(const void*a, const void *b) {
                         return -1;
                 else if (y->memory_valid)
                         return 1;
-        }
 
-        if (arg_order == ORDER_IO) {
+                break;
+
+        case ORDER_IO:
                 if (x->io_valid && y->io_valid) {
                         if (x->io_input_bps + x->io_output_bps > y->io_input_bps + y->io_output_bps)
                                 return -1;
@@ -448,7 +447,7 @@ static int group_compare(const void*a, const void *b) {
                         return 1;
         }
 
-        return strcmp(x->path, y->path);
+        return path_compare(x->path, y->path);
 }
 
 #define ON ANSI_HIGHLIGHT_ON
@@ -481,9 +480,10 @@ static int display(Hashmap *a) {
         for (j = 0; j < n; j++) {
                 unsigned cputlen, pathtlen;
 
-                format_timespan(buffer, sizeof(buffer), (nsec_t) (array[j]->cpu_usage / NSEC_PER_USEC), 0);
+                format_timespan(buffer, sizeof(buffer), (usec_t) (array[j]->cpu_usage / NSEC_PER_USEC), 0);
                 cputlen = strlen(buffer);
                 maxtcpu = MAX(maxtcpu, cputlen);
+
                 pathtlen = strlen(array[j]->path);
                 maxtpath = MAX(maxtpath, pathtlen);
         }
@@ -503,7 +503,7 @@ static int display(Hashmap *a) {
                         path_columns = 10;
 
                 printf("%s%-*s%s %s%7s%s %s%s%s %s%8s%s %s%8s%s %s%8s%s\n\n",
-                       arg_order == ORDER_PATH ? ON : "", path_columns, "Path",
+                       arg_order == ORDER_PATH ? ON : "", path_columns, "Control Group",
                        arg_order == ORDER_PATH ? OFF : "",
                        arg_order == ORDER_TASKS ? ON : "", "Tasks",
                        arg_order == ORDER_TASKS ? OFF : "",
@@ -519,7 +519,7 @@ static int display(Hashmap *a) {
                 path_columns = maxtpath;
 
         for (j = 0; j < n; j++) {
-                char *p;
+                _cleanup_free_ char *p = NULL;
 
                 if (on_tty() && j + 5 > rows)
                         break;
@@ -527,8 +527,7 @@ static int display(Hashmap *a) {
                 g = array[j];
 
                 p = ellipsize(g->path, path_columns, 33);
-                printf("%-*s", path_columns, p ? p : g->path);
-                free(p);
+                printf("%-*s", path_columns, p ?: g->path);
 
                 if (g->n_tasks_valid)
                         printf(" %7u", g->n_tasks);
@@ -541,7 +540,7 @@ static int display(Hashmap *a) {
                         else
                                 fputs("      -", stdout);
                 } else
-                        printf(" %*s", maxtcpu, format_timespan(buffer, sizeof(buffer), (nsec_t) (g->cpu_usage / NSEC_PER_USEC), 0));
+                        printf(" %*s", maxtcpu, format_timespan(buffer, sizeof(buffer), (usec_t) (g->cpu_usage / NSEC_PER_USEC), 0));
 
                 printf(" %8s", maybe_format_bytes(buffer, sizeof(buffer), g->memory_valid, g->memory));
                 printf(" %8s", maybe_format_bytes(buffer, sizeof(buffer), g->io_valid, g->io_input_bps));
@@ -557,14 +556,15 @@ static void help(void) {
         printf("%s [OPTIONS...]\n\n"
                "Show top control groups by their resource usage.\n\n"
                "  -h --help           Show this help\n"
-               "  --version           Print version and exit\n"
-               "  -p                  Order by path\n"
-               "  -t                  Order by number of tasks\n"
-               "  -c                  Order by CPU load\n"
-               "  -m                  Order by memory load\n"
-               "  -i                  Order by IO load\n"
+               "     --version        Show package version\n"
+               "  -p --order=path     Order by path\n"
+               "  -t --order=tasks    Order by number of tasks\n"
+               "  -c --order=cpu      Order by CPU load (default)\n"
+               "  -m --order=memory   Order by memory load\n"
+               "  -i --order=io       Order by IO load\n"
                "  -r --raw            Provide raw (not human-readable) numbers\n"
-               "     --cpu[=TYPE]     Show CPU usage as time or percentage (default)\n"
+               "     --cpu=percentage Show CPU usage as percentage (default)\n"
+               "     --cpu=time       Show CPU usage as time\n"
                "  -d --delay=DELAY    Delay between updates\n"
                "  -n --iterations=N   Run for N iterations before exiting\n"
                "  -b --batch          Run in batch mode, accepting no input\n"
@@ -577,18 +577,20 @@ static int parse_argv(int argc, char *argv[]) {
         enum {
                 ARG_VERSION = 0x100,
                 ARG_DEPTH,
-                ARG_CPU_TYPE
+                ARG_CPU_TYPE,
+                ARG_ORDER,
         };
 
         static const struct option options[] = {
-                { "help",       no_argument,       NULL, 'h'         },
-                { "version",    no_argument,       NULL, ARG_VERSION },
-                { "delay",      required_argument, NULL, 'd'         },
-                { "iterations", required_argument, NULL, 'n'         },
-                { "batch",      no_argument,       NULL, 'b'         },
-                { "raw",        no_argument,       NULL, 'r'         },
-                { "depth",      required_argument, NULL, ARG_DEPTH   },
-                { "cpu",        optional_argument, NULL, ARG_CPU_TYPE},
+                { "help",         no_argument,       NULL, 'h'          },
+                { "version",      no_argument,       NULL, ARG_VERSION  },
+                { "delay",        required_argument, NULL, 'd'          },
+                { "iterations",   required_argument, NULL, 'n'          },
+                { "batch",        no_argument,       NULL, 'b'          },
+                { "raw",          no_argument,       NULL, 'r'          },
+                { "depth",        required_argument, NULL, ARG_DEPTH    },
+                { "cpu",          optional_argument, NULL, ARG_CPU_TYPE },
+                { "order",        required_argument, NULL, ARG_ORDER    },
                 {}
         };
 
@@ -613,13 +615,17 @@ static int parse_argv(int argc, char *argv[]) {
 
                 case ARG_CPU_TYPE:
                         if (optarg) {
-                                if (strcmp(optarg, "time") == 0)
+                                if (streq(optarg, "time"))
                                         arg_cpu_type = CPU_TIME;
-                                else if (strcmp(optarg, "percentage") == 0)
+                                else if (streq(optarg, "percentage"))
                                         arg_cpu_type = CPU_PERCENT;
-                                else
+                                else {
+                                        log_error("Unknown argument to --cpu=: %s", optarg);
                                         return -EINVAL;
-                        }
+                                }
+                        } else
+                                arg_cpu_type = CPU_TIME;
+
                         break;
 
                 case ARG_DEPTH:
@@ -677,6 +683,23 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_order = ORDER_IO;
                         break;
 
+                case ARG_ORDER:
+                        if (streq(optarg, "path"))
+                                arg_order = ORDER_PATH;
+                        else if (streq(optarg, "tasks"))
+                                arg_order = ORDER_TASKS;
+                        else if (streq(optarg, "cpu"))
+                                arg_order = ORDER_CPU;
+                        else if (streq(optarg, "memory"))
+                                arg_order = ORDER_MEMORY;
+                        else if (streq(optarg, "io"))
+                                arg_order = ORDER_IO;
+                        else {
+                                log_error("Invalid argument to --order=: %s", optarg);
+                                return -EINVAL;
+                        }
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -715,7 +738,7 @@ int main(int argc, char *argv[]) {
 
         signal(SIGWINCH, columns_lines_cache_reset);
 
-        if (arg_iterations == (unsigned)-1)
+        if (arg_iterations == (unsigned) -1)
                 arg_iterations = on_tty() ? 0 : 1;
 
         while (!quit) {
@@ -753,11 +776,10 @@ int main(int argc, char *argv[]) {
                         fputs("\n", stdout);
                 fflush(stdout);
 
-                if (arg_batch) {
+                if (arg_batch)
                         usleep(last_refresh + arg_delay - t);
-                } else {
-                        r = read_one_char(stdin, &key,
-                                          last_refresh + arg_delay - t, NULL);
+                else {
+                        r = read_one_char(stdin, &key, last_refresh + arg_delay - t, NULL);
                         if (r == -ETIMEDOUT)
                                 continue;
                         if (r < 0) {
@@ -843,7 +865,10 @@ int main(int argc, char *argv[]) {
                         break;
 
                 default:
-                        fprintf(stdout, "\nUnknown key '%c'. Ignoring.", key);
+                        if (key < ' ')
+                                fprintf(stdout, "\nUnknown key '\\x%x'. Ignoring.", key);
+                        else
+                                fprintf(stdout, "\nUnknown key '%c'. Ignoring.", key);
                         fflush(stdout);
                         sleep(1);
                         break;
diff --git a/src/core/automount.c b/src/core/automount.c
index 4af381b4b6..b8171ddad7 100644
--- a/src/core/automount.c
+++ b/src/core/automount.c
@@ -1075,7 +1075,6 @@ const UnitVTable automount_vtable = {
 
         .reset_failed = automount_reset_failed,
 
-        .bus_interface = "org.freedesktop.systemd1.Automount",
         .bus_vtable = bus_automount_vtable,
 
         .shutdown = automount_shutdown,
diff --git a/src/core/busname.c b/src/core/busname.c
index 9530a87311..d3c1282239 100644
--- a/src/core/busname.c
+++ b/src/core/busname.c
@@ -1058,7 +1058,6 @@ const UnitVTable busname_vtable = {
 
         .supported = busname_supported,
 
-        .bus_interface = "org.freedesktop.systemd1.BusName",
         .bus_vtable = bus_busname_vtable,
 
         .status_message_formats = {
diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c
index 0a9effda71..42bb653cc1 100644
--- a/src/core/dbus-unit.c
+++ b/src/core/dbus-unit.c
@@ -783,7 +783,7 @@ static int send_changed_signal(sd_bus *bus, void *userdata) {
 
         r = sd_bus_emit_properties_changed_strv(
                         bus, p,
-                        UNIT_VTABLE(u)->bus_interface,
+                        unit_dbus_interface_from_type(u->type),
                         NULL);
         if (r < 0)
                 return r;
diff --git a/src/core/dbus.c b/src/core/dbus.c
index 44bf5cab28..d091aa5419 100644
--- a/src/core/dbus.c
+++ b/src/core/dbus.c
@@ -356,7 +356,7 @@ static int bus_unit_interface_find(sd_bus *bus, const char *path, const char *in
         if (r <= 0)
                 return r;
 
-        if (!streq_ptr(interface, UNIT_VTABLE(u)->bus_interface))
+        if (!streq_ptr(interface, unit_dbus_interface_from_type(u->type)))
                 return 0;
 
         *found = u;
@@ -378,7 +378,7 @@ static int bus_unit_cgroup_find(sd_bus *bus, const char *path, const char *inter
         if (r <= 0)
                 return r;
 
-        if (!streq_ptr(interface, UNIT_VTABLE(u)->bus_interface))
+        if (!streq_ptr(interface, unit_dbus_interface_from_type(u->type)))
                 return 0;
 
         if (!unit_get_cgroup_context(u))
@@ -404,7 +404,7 @@ static int bus_cgroup_context_find(sd_bus *bus, const char *path, const char *in
         if (r <= 0)
                 return r;
 
-        if (!streq_ptr(interface, UNIT_VTABLE(u)->bus_interface))
+        if (!streq_ptr(interface, unit_dbus_interface_from_type(u->type)))
                 return 0;
 
         c = unit_get_cgroup_context(u);
@@ -431,7 +431,7 @@ static int bus_exec_context_find(sd_bus *bus, const char *path, const char *inte
         if (r <= 0)
                 return r;
 
-        if (!streq_ptr(interface, UNIT_VTABLE(u)->bus_interface))
+        if (!streq_ptr(interface, unit_dbus_interface_from_type(u->type)))
                 return 0;
 
         c = unit_get_exec_context(u);
@@ -458,7 +458,7 @@ static int bus_kill_context_find(sd_bus *bus, const char *path, const char *inte
         if (r <= 0)
                 return r;
 
-        if (!streq_ptr(interface, UNIT_VTABLE(u)->bus_interface))
+        if (!streq_ptr(interface, unit_dbus_interface_from_type(u->type)))
                 return 0;
 
         c = unit_get_kill_context(u);
@@ -555,30 +555,34 @@ static int bus_setup_api_vtables(Manager *m, sd_bus *bus) {
                 return log_error_errno(r, "Failed to add job enumerator: %m");
 
         for (t = 0; t < _UNIT_TYPE_MAX; t++) {
-                r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", unit_vtable[t]->bus_interface, unit_vtable[t]->bus_vtable, bus_unit_interface_find, m);
+                const char *interface;
+
+                assert_se(interface = unit_dbus_interface_from_type(t));
+
+                r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", interface, unit_vtable[t]->bus_vtable, bus_unit_interface_find, m);
                 if (r < 0)
-                        return log_error_errno(r, "Failed to register type specific vtable for %s: %m", unit_vtable[t]->bus_interface);
+                        return log_error_errno(r, "Failed to register type specific vtable for %s: %m", interface);
 
                 if (unit_vtable[t]->cgroup_context_offset > 0) {
-                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", unit_vtable[t]->bus_interface, bus_unit_cgroup_vtable, bus_unit_cgroup_find, m);
+                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", interface, bus_unit_cgroup_vtable, bus_unit_cgroup_find, m);
                         if (r < 0)
-                                return log_error_errno(r, "Failed to register control group unit vtable for %s: %m", unit_vtable[t]->bus_interface);
+                                return log_error_errno(r, "Failed to register control group unit vtable for %s: %m", interface);
 
-                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", unit_vtable[t]->bus_interface, bus_cgroup_vtable, bus_cgroup_context_find, m);
+                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", interface, bus_cgroup_vtable, bus_cgroup_context_find, m);
                         if (r < 0)
-                                return log_error_errno(r, "Failed to register control group vtable for %s: %m", unit_vtable[t]->bus_interface);
+                                return log_error_errno(r, "Failed to register control group vtable for %s: %m", interface);
                 }
 
                 if (unit_vtable[t]->exec_context_offset > 0) {
-                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", unit_vtable[t]->bus_interface, bus_exec_vtable, bus_exec_context_find, m);
+                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", interface, bus_exec_vtable, bus_exec_context_find, m);
                         if (r < 0)
-                                return log_error_errno(r, "Failed to register execute vtable for %s: %m", unit_vtable[t]->bus_interface);
+                                return log_error_errno(r, "Failed to register execute vtable for %s: %m", interface);
                 }
 
                 if (unit_vtable[t]->kill_context_offset > 0) {
-                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", unit_vtable[t]->bus_interface, bus_kill_vtable, bus_kill_context_find, m);
+                        r = sd_bus_add_fallback_vtable(bus, NULL, "/org/freedesktop/systemd1/unit", interface, bus_kill_vtable, bus_kill_context_find, m);
                         if (r < 0)
-                                return log_error_errno(r, "Failed to register kill vtable for %s: %m", unit_vtable[t]->bus_interface);
+                                return log_error_errno(r, "Failed to register kill vtable for %s: %m", interface);
                 }
         }
 
diff --git a/src/core/device.c b/src/core/device.c
index e7efcf0f0a..3f574b1832 100644
--- a/src/core/device.c
+++ b/src/core/device.c
@@ -849,7 +849,6 @@ const UnitVTable device_vtable = {
         .active_state = device_active_state,
         .sub_state_to_string = device_sub_state_to_string,
 
-        .bus_interface = "org.freedesktop.systemd1.Device",
         .bus_vtable = bus_device_vtable,
 
         .following = device_following,
diff --git a/src/core/mount.c b/src/core/mount.c
index c0d1cdfbd4..7e19e66a51 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -1871,7 +1871,6 @@ const UnitVTable mount_vtable = {
 
         .reset_failed = mount_reset_failed,
 
-        .bus_interface = "org.freedesktop.systemd1.Mount",
         .bus_vtable = bus_mount_vtable,
         .bus_set_property = bus_mount_set_property,
         .bus_commit_properties = bus_mount_commit_properties,
diff --git a/src/core/path.c b/src/core/path.c
index 20995d920c..e9111d0612 100644
--- a/src/core/path.c
+++ b/src/core/path.c
@@ -770,6 +770,5 @@ const UnitVTable path_vtable = {
 
         .reset_failed = path_reset_failed,
 
-        .bus_interface = "org.freedesktop.systemd1.Path",
         .bus_vtable = bus_path_vtable
 };
diff --git a/src/core/scope.c b/src/core/scope.c
index ab1769b46b..bf89936153 100644
--- a/src/core/scope.c
+++ b/src/core/scope.c
@@ -561,7 +561,6 @@ const UnitVTable scope_vtable = {
 
         .notify_cgroup_empty = scope_notify_cgroup_empty_event,
 
-        .bus_interface = "org.freedesktop.systemd1.Scope",
         .bus_vtable = bus_scope_vtable,
         .bus_set_property = bus_scope_set_property,
         .bus_commit_properties = bus_scope_commit_properties,
diff --git a/src/core/service.c b/src/core/service.c
index b790ec98be..097e7c710c 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -3214,7 +3214,6 @@ const UnitVTable service_vtable = {
 
         .bus_name_owner_change = service_bus_name_owner_change,
 
-        .bus_interface = "org.freedesktop.systemd1.Service",
         .bus_vtable = bus_service_vtable,
         .bus_set_property = bus_service_set_property,
         .bus_commit_properties = bus_service_commit_properties,
diff --git a/src/core/slice.c b/src/core/slice.c
index 064eb5d933..7442d23391 100644
--- a/src/core/slice.c
+++ b/src/core/slice.c
@@ -289,7 +289,6 @@ const UnitVTable slice_vtable = {
         .active_state = slice_active_state,
         .sub_state_to_string = slice_sub_state_to_string,
 
-        .bus_interface = "org.freedesktop.systemd1.Slice",
         .bus_vtable = bus_slice_vtable,
         .bus_set_property = bus_slice_set_property,
         .bus_commit_properties = bus_slice_commit_properties,
diff --git a/src/core/snapshot.c b/src/core/snapshot.c
index 9518e21f36..336ff20f84 100644
--- a/src/core/snapshot.c
+++ b/src/core/snapshot.c
@@ -302,6 +302,5 @@ const UnitVTable snapshot_vtable = {
         .active_state = snapshot_active_state,
         .sub_state_to_string = snapshot_sub_state_to_string,
 
-        .bus_interface = "org.freedesktop.systemd1.Snapshot",
         .bus_vtable = bus_snapshot_vtable
 };
diff --git a/src/core/socket.c b/src/core/socket.c
index a387057473..08efc3754c 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -2709,7 +2709,6 @@ const UnitVTable socket_vtable = {
 
         .reset_failed = socket_reset_failed,
 
-        .bus_interface = "org.freedesktop.systemd1.Socket",
         .bus_vtable = bus_socket_vtable,
         .bus_set_property = bus_socket_set_property,
         .bus_commit_properties = bus_socket_commit_properties,
diff --git a/src/core/swap.c b/src/core/swap.c
index 0bc3827ff0..349fd6f7b9 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -1485,7 +1485,6 @@ const UnitVTable swap_vtable = {
 
         .reset_failed = swap_reset_failed,
 
-        .bus_interface = "org.freedesktop.systemd1.Swap",
         .bus_vtable = bus_swap_vtable,
         .bus_set_property = bus_swap_set_property,
         .bus_commit_properties = bus_swap_commit_properties,
diff --git a/src/core/target.c b/src/core/target.c
index b492a7c4c7..f714cb31c2 100644
--- a/src/core/target.c
+++ b/src/core/target.c
@@ -221,7 +221,6 @@ const UnitVTable target_vtable = {
         .active_state = target_active_state,
         .sub_state_to_string = target_sub_state_to_string,
 
-        .bus_interface = "org.freedesktop.systemd1.Target",
         .bus_vtable = bus_target_vtable,
 
         .status_message_formats = {
diff --git a/src/core/timer.c b/src/core/timer.c
index 89758c6b19..eb6567bbfa 100644
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -772,7 +772,6 @@ const UnitVTable timer_vtable = {
         .reset_failed = timer_reset_failed,
         .time_change = timer_time_change,
 
-        .bus_interface = "org.freedesktop.systemd1.Timer",
         .bus_vtable = bus_timer_vtable,
         .bus_set_property = bus_timer_set_property,
 
diff --git a/src/core/unit.h b/src/core/unit.h
index 9df5a7e6fb..f53b7f6da1 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -404,9 +404,6 @@ struct UnitVTable {
          * of this type will immediately fail. */
         bool (*supported)(void);
 
-        /* The interface name */
-        const char *bus_interface;
-
         /* The bus vtable */
         const sd_bus_vtable *bus_vtable;
 
diff --git a/src/machine/machinectl.c b/src/machine/machinectl.c
index 926035d185..8bd0ed756b 100644
--- a/src/machine/machinectl.c
+++ b/src/machine/machinectl.c
@@ -361,8 +361,7 @@ static int show_unit_cgroup(sd_bus *bus, const char *unit, pid_t leader) {
                         bus,
                         "org.freedesktop.systemd1",
                         path,
-                        endswith(unit, ".scope") ? "org.freedesktop.systemd1.Scope" :
-                        endswith(unit, ".slice") ? "org.freedesktop.systemd1.Slice" : "org.freedesktop.systemd1.Service",
+                        unit_dbus_interface_from_name(unit),
                         "ControlGroup",
                         &error,
                         &reply,