core: add cgroup CPU controller support on the unified hierarchy

Unfortunately, due to the disagreements in the kernel development community,
CPU controller cgroup v2 support has not been merged and enabling it requires
applying two small out-of-tree kernel patches.  The situation is explained in
the following documentation.

 https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/tree/Documentation/cgroup-v2-cpu.txt?h=cgroup-v2-cpu

While it isn't clear what will happen with CPU controller cgroup v2 support,
there are critical features which are possible only on cgroup v2 such as
buffered write control making cgroup v2 essential for a lot of workloads.  This
commit implements systemd CPU controller support on the unified hierarchy so
that users who choose to deploy CPU controller cgroup v2 support can easily
take advantage of it.

On the unified hierarchy, "cpu.weight" knob replaces "cpu.shares" and "cpu.max"
replaces "cpu.cfs_period_us" and "cpu.cfs_quota_us".  [Startup]CPUWeight config
options are added with the usual compat translation.  CPU quota settings remain
unchanged and apply to both legacy and unified hierarchies.

v2: - Error in man page corrected.
    - CPU config application in cgroup_context_apply() refactored.
    - CPU accounting now works on unified hierarchy.

8 files changed, 252 insertions, 44 deletions

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index c19e43f571..910a64b4da 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -57,9 +57,12 @@ void cgroup_context_init(CGroupContext *c) {
         /* Initialize everything to the kernel defaults, assuming the
          * structure is preinitialized to 0 */
 
+        c->cpu_weight = CGROUP_WEIGHT_INVALID;
+        c->startup_cpu_weight = CGROUP_WEIGHT_INVALID;
+        c->cpu_quota_per_sec_usec = USEC_INFINITY;
+
         c->cpu_shares = CGROUP_CPU_SHARES_INVALID;
         c->startup_cpu_shares = CGROUP_CPU_SHARES_INVALID;
-        c->cpu_quota_per_sec_usec = USEC_INFINITY;
 
         c->memory_high = CGROUP_LIMIT_MAX;
         c->memory_max = CGROUP_LIMIT_MAX;
@@ -158,6 +161,8 @@ void cgroup_context_dump(CGroupContext *c, FILE* f, const char *prefix) {
                 "%sBlockIOAccounting=%s\n"
                 "%sMemoryAccounting=%s\n"
                 "%sTasksAccounting=%s\n"
+                "%sCPUWeight=%" PRIu64 "\n"
+                "%sStartupCPUWeight=%" PRIu64 "\n"
                 "%sCPUShares=%" PRIu64 "\n"
                 "%sStartupCPUShares=%" PRIu64 "\n"
                 "%sCPUQuotaPerSecSec=%s\n"
@@ -177,6 +182,8 @@ void cgroup_context_dump(CGroupContext *c, FILE* f, const char *prefix) {
                 prefix, yes_no(c->blockio_accounting),
                 prefix, yes_no(c->memory_accounting),
                 prefix, yes_no(c->tasks_accounting),
+                prefix, c->cpu_weight,
+                prefix, c->startup_cpu_weight,
                 prefix, c->cpu_shares,
                 prefix, c->startup_cpu_shares,
                 prefix, format_timespan(u, sizeof(u), c->cpu_quota_per_sec_usec, 1),
@@ -382,6 +389,95 @@ fail:
         return -errno;
 }
 
+static bool cgroup_context_has_cpu_weight(CGroupContext *c) {
+        return c->cpu_weight != CGROUP_WEIGHT_INVALID ||
+                c->startup_cpu_weight != CGROUP_WEIGHT_INVALID;
+}
+
+static bool cgroup_context_has_cpu_shares(CGroupContext *c) {
+        return c->cpu_shares != CGROUP_CPU_SHARES_INVALID ||
+                c->startup_cpu_shares != CGROUP_CPU_SHARES_INVALID;
+}
+
+static uint64_t cgroup_context_cpu_weight(CGroupContext *c, ManagerState state) {
+        if (IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING) &&
+            c->startup_cpu_weight != CGROUP_WEIGHT_INVALID)
+                return c->startup_cpu_weight;
+        else if (c->cpu_weight != CGROUP_WEIGHT_INVALID)
+                return c->cpu_weight;
+        else
+                return CGROUP_WEIGHT_DEFAULT;
+}
+
+static uint64_t cgroup_context_cpu_shares(CGroupContext *c, ManagerState state) {
+        if (IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING) &&
+            c->startup_cpu_shares != CGROUP_CPU_SHARES_INVALID)
+                return c->startup_cpu_shares;
+        else if (c->cpu_shares != CGROUP_CPU_SHARES_INVALID)
+                return c->cpu_shares;
+        else
+                return CGROUP_CPU_SHARES_DEFAULT;
+}
+
+static void cgroup_apply_unified_cpu_config(Unit *u, uint64_t weight, uint64_t quota) {
+        char buf[MAX(DECIMAL_STR_MAX(uint64_t) + 1, (DECIMAL_STR_MAX(usec_t) + 1) * 2)];
+        int r;
+
+        xsprintf(buf, "%" PRIu64 "\n", weight);
+        r = cg_set_attribute("cpu", u->cgroup_path, "cpu.weight", buf);
+        if (r < 0)
+                log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
+                              "Failed to set cpu.weight: %m");
+
+        if (quota != USEC_INFINITY)
+                xsprintf(buf, USEC_FMT " " USEC_FMT "\n",
+                         quota * CGROUP_CPU_QUOTA_PERIOD_USEC / USEC_PER_SEC, CGROUP_CPU_QUOTA_PERIOD_USEC);
+        else
+                xsprintf(buf, "max " USEC_FMT "\n", CGROUP_CPU_QUOTA_PERIOD_USEC);
+
+        r = cg_set_attribute("cpu", u->cgroup_path, "cpu.max", buf);
+
+        if (r < 0)
+                log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
+                              "Failed to set cpu.max: %m");
+}
+
+static void cgroup_apply_legacy_cpu_config(Unit *u, uint64_t shares, uint64_t quota) {
+        char buf[MAX(DECIMAL_STR_MAX(uint64_t), DECIMAL_STR_MAX(usec_t)) + 1];
+        int r;
+
+        xsprintf(buf, "%" PRIu64 "\n", shares);
+        r = cg_set_attribute("cpu", u->cgroup_path, "cpu.shares", buf);
+        if (r < 0)
+                log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
+                              "Failed to set cpu.shares: %m");
+
+        xsprintf(buf, USEC_FMT "\n", CGROUP_CPU_QUOTA_PERIOD_USEC);
+        r = cg_set_attribute("cpu", u->cgroup_path, "cpu.cfs_period_us", buf);
+        if (r < 0)
+                log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
+                              "Failed to set cpu.cfs_period_us: %m");
+
+        if (quota != USEC_INFINITY) {
+                xsprintf(buf, USEC_FMT "\n", quota * CGROUP_CPU_QUOTA_PERIOD_USEC / USEC_PER_SEC);
+                r = cg_set_attribute("cpu", u->cgroup_path, "cpu.cfs_quota_us", buf);
+        } else
+                r = cg_set_attribute("cpu", u->cgroup_path, "cpu.cfs_quota_us", "-1");
+        if (r < 0)
+                log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
+                              "Failed to set cpu.cfs_quota_us: %m");
+}
+
+static uint64_t cgroup_cpu_shares_to_weight(uint64_t shares) {
+        return CLAMP(shares * CGROUP_WEIGHT_DEFAULT / CGROUP_CPU_SHARES_DEFAULT,
+                     CGROUP_WEIGHT_MIN, CGROUP_WEIGHT_MAX);
+}
+
+static uint64_t cgroup_cpu_weight_to_shares(uint64_t weight) {
+        return CLAMP(weight * CGROUP_CPU_SHARES_DEFAULT / CGROUP_WEIGHT_DEFAULT,
+                     CGROUP_CPU_SHARES_MIN, CGROUP_CPU_SHARES_MAX);
+}
+
 static bool cgroup_context_has_io_config(CGroupContext *c) {
         return c->io_accounting ||
                 c->io_weight != CGROUP_WEIGHT_INVALID ||
@@ -566,30 +662,42 @@ static void cgroup_context_apply(Unit *u, CGroupMask mask, ManagerState state) {
          * and missing cgroups, i.e. EROFS and ENOENT. */
 
         if ((mask & CGROUP_MASK_CPU) && !is_root) {
-                char buf[MAX(DECIMAL_STR_MAX(uint64_t), DECIMAL_STR_MAX(usec_t)) + 1];
+                bool has_weight = cgroup_context_has_cpu_weight(c);
+                bool has_shares = cgroup_context_has_cpu_shares(c);
 
-                sprintf(buf, "%" PRIu64 "\n",
-                        IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING) && c->startup_cpu_shares != CGROUP_CPU_SHARES_INVALID ? c->startup_cpu_shares :
-                        c->cpu_shares != CGROUP_CPU_SHARES_INVALID ? c->cpu_shares : CGROUP_CPU_SHARES_DEFAULT);
-                r = cg_set_attribute("cpu", path, "cpu.shares", buf);
-                if (r < 0)
-                        log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
-                                      "Failed to set cpu.shares: %m");
+                if (cg_unified() > 0) {
+                        uint64_t weight;
 
-                sprintf(buf, USEC_FMT "\n", CGROUP_CPU_QUOTA_PERIOD_USEC);
-                r = cg_set_attribute("cpu", path, "cpu.cfs_period_us", buf);
-                if (r < 0)
-                        log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
-                                      "Failed to set cpu.cfs_period_us: %m");
+                        if (has_weight)
+                                weight = cgroup_context_cpu_weight(c, state);
+                        else if (has_shares) {
+                                uint64_t shares = cgroup_context_cpu_shares(c, state);
 
-                if (c->cpu_quota_per_sec_usec != USEC_INFINITY) {
-                        sprintf(buf, USEC_FMT "\n", c->cpu_quota_per_sec_usec * CGROUP_CPU_QUOTA_PERIOD_USEC / USEC_PER_SEC);
-                        r = cg_set_attribute("cpu", path, "cpu.cfs_quota_us", buf);
-                } else
-                        r = cg_set_attribute("cpu", path, "cpu.cfs_quota_us", "-1");
-                if (r < 0)
-                        log_unit_full(u, IN_SET(r, -ENOENT, -EROFS, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
-                                      "Failed to set cpu.cfs_quota_us: %m");
+                                weight = cgroup_cpu_shares_to_weight(shares);
+
+                                log_cgroup_compat(u, "Applying [Startup]CpuShares %" PRIu64 " as [Startup]CpuWeight %" PRIu64 " on %s",
+                                                  shares, weight, path);
+                        } else
+                                weight = CGROUP_WEIGHT_DEFAULT;
+
+                        cgroup_apply_unified_cpu_config(u, weight, c->cpu_quota_per_sec_usec);
+                } else {
+                        uint64_t shares;
+
+                        if (has_shares)
+                                shares = cgroup_context_cpu_shares(c, state);
+                        else if (has_weight) {
+                                uint64_t weight = cgroup_context_cpu_weight(c, state);
+
+                                shares = cgroup_cpu_weight_to_shares(weight);
+
+                                log_cgroup_compat(u, "Applying [Startup]CpuWeight %" PRIu64 " as [Startup]CpuShares %" PRIu64 " on %s",
+                                                  weight, shares, path);
+                        } else
+                                shares = CGROUP_CPU_SHARES_DEFAULT;
+
+                        cgroup_apply_legacy_cpu_config(u, shares, c->cpu_quota_per_sec_usec);
+                }
         }
 
         if (mask & CGROUP_MASK_IO) {
@@ -864,8 +972,8 @@ CGroupMask cgroup_context_get_mask(CGroupContext *c) {
         /* Figure out which controllers we need */
 
         if (c->cpu_accounting ||
-            c->cpu_shares != CGROUP_CPU_SHARES_INVALID ||
-            c->startup_cpu_shares != CGROUP_CPU_SHARES_INVALID ||
+            cgroup_context_has_cpu_weight(c) ||
+            cgroup_context_has_cpu_shares(c) ||
             c->cpu_quota_per_sec_usec != USEC_INFINITY)
                 mask |= CGROUP_MASK_CPUACCT | CGROUP_MASK_CPU;
 
@@ -1890,18 +1998,37 @@ static int unit_get_cpu_usage_raw(Unit *u, nsec_t *ret) {
         if (!u->cgroup_path)
                 return -ENODATA;
 
-        if ((u->cgroup_realized_mask & CGROUP_MASK_CPUACCT) == 0)
-                return -ENODATA;
+        if (cg_unified() > 0) {
+                const char *keys[] = { "usage_usec", NULL };
+                _cleanup_free_ char *val = NULL;
+                uint64_t us;
 
-        r = cg_get_attribute("cpuacct", u->cgroup_path, "cpuacct.usage", &v);
-        if (r == -ENOENT)
-                return -ENODATA;
-        if (r < 0)
-                return r;
+                if ((u->cgroup_realized_mask & CGROUP_MASK_CPU) == 0)
+                        return -ENODATA;
 
-        r = safe_atou64(v, &ns);
-        if (r < 0)
-                return r;
+                r = cg_get_keyed_attribute("cpu", u->cgroup_path, "cpu.stat", keys, &val);
+                if (r < 0)
+                        return r;
+
+                r = safe_atou64(val, &us);
+                if (r < 0)
+                        return r;
+
+                ns = us * NSEC_PER_USEC;
+        } else {
+                if ((u->cgroup_realized_mask & CGROUP_MASK_CPUACCT) == 0)
+                        return -ENODATA;
+
+                r = cg_get_attribute("cpuacct", u->cgroup_path, "cpuacct.usage", &v);
+                if (r == -ENOENT)
+                        return -ENODATA;
+                if (r < 0)
+                        return r;
+
+                r = safe_atou64(v, &ns);
+                if (r < 0)
+                        return r;
+        }
 
         *ret = ns;
         return 0;
@@ -1915,8 +2042,8 @@ int unit_get_cpu_usage(Unit *u, nsec_t *ret) {
         if (r < 0)
                 return r;
 
-        if (ns > u->cpuacct_usage_base)
-                ns -= u->cpuacct_usage_base;
+        if (ns > u->cpu_usage_base)
+                ns -= u->cpu_usage_base;
         else
                 ns = 0;
 
@@ -1932,11 +2059,11 @@ int unit_reset_cpu_usage(Unit *u) {
 
         r = unit_get_cpu_usage_raw(u, &ns);
         if (r < 0) {
-                u->cpuacct_usage_base = 0;
+                u->cpu_usage_base = 0;
                 return r;
         }
 
-        u->cpuacct_usage_base = ns;
+        u->cpu_usage_base = ns;
         return 0;
 }
 
diff --git a/src/core/cgroup.h b/src/core/cgroup.h
index a57403e79f..2fe9cc4039 100644
--- a/src/core/cgroup.h
+++ b/src/core/cgroup.h
@@ -89,6 +89,10 @@ struct CGroupContext {
         bool tasks_accounting;
 
         /* For unified hierarchy */
+        uint64_t cpu_weight;
+        uint64_t startup_cpu_weight;
+        usec_t cpu_quota_per_sec_usec;
+
         uint64_t io_weight;
         uint64_t startup_io_weight;
         LIST_HEAD(CGroupIODeviceWeight, io_device_weights);
@@ -101,7 +105,6 @@ struct CGroupContext {
         /* For legacy hierarchies */
         uint64_t cpu_shares;
         uint64_t startup_cpu_shares;
-        usec_t cpu_quota_per_sec_usec;
 
         uint64_t blockio_weight;
         uint64_t startup_blockio_weight;
diff --git a/src/core/dbus-cgroup.c b/src/core/dbus-cgroup.c
index 85b0c86a2f..2ca80d2996 100644
--- a/src/core/dbus-cgroup.c
+++ b/src/core/dbus-cgroup.c
@@ -210,6 +210,8 @@ const sd_bus_vtable bus_cgroup_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("Delegate", "b", bus_property_get_bool, offsetof(CGroupContext, delegate), 0),
         SD_BUS_PROPERTY("CPUAccounting", "b", bus_property_get_bool, offsetof(CGroupContext, cpu_accounting), 0),
+        SD_BUS_PROPERTY("CPUWeight", "t", NULL, offsetof(CGroupContext, cpu_weight), 0),
+        SD_BUS_PROPERTY("StartupCPUWeight", "t", NULL, offsetof(CGroupContext, startup_cpu_weight), 0),
         SD_BUS_PROPERTY("CPUShares", "t", NULL, offsetof(CGroupContext, cpu_shares), 0),
         SD_BUS_PROPERTY("StartupCPUShares", "t", NULL, offsetof(CGroupContext, startup_cpu_shares), 0),
         SD_BUS_PROPERTY("CPUQuotaPerSecUSec", "t", bus_property_get_usec, offsetof(CGroupContext, cpu_quota_per_sec_usec), 0),
@@ -303,6 +305,50 @@ int bus_cgroup_set_property(
 
                 return 1;
 
+        } else if (streq(name, "CPUWeight")) {
+                uint64_t weight;
+
+                r = sd_bus_message_read(message, "t", &weight);
+                if (r < 0)
+                        return r;
+
+                if (!CGROUP_WEIGHT_IS_OK(weight))
+                        return sd_bus_error_set_errnof(error, EINVAL, "CPUWeight value out of range");
+
+                if (mode != UNIT_CHECK) {
+                        c->cpu_weight = weight;
+                        unit_invalidate_cgroup(u, CGROUP_MASK_CPU);
+
+                        if (weight == CGROUP_WEIGHT_INVALID)
+                                unit_write_drop_in_private(u, mode, name, "CPUWeight=");
+                        else
+                                unit_write_drop_in_private_format(u, mode, name, "CPUWeight=%" PRIu64, weight);
+                }
+
+                return 1;
+
+        } else if (streq(name, "StartupCPUWeight")) {
+                uint64_t weight;
+
+                r = sd_bus_message_read(message, "t", &weight);
+                if (r < 0)
+                        return r;
+
+                if (!CGROUP_WEIGHT_IS_OK(weight))
+                        return sd_bus_error_set_errnof(error, EINVAL, "StartupCPUWeight value out of range");
+
+                if (mode != UNIT_CHECK) {
+                        c->startup_cpu_weight = weight;
+                        unit_invalidate_cgroup(u, CGROUP_MASK_CPU);
+
+                        if (weight == CGROUP_CPU_SHARES_INVALID)
+                                unit_write_drop_in_private(u, mode, name, "StartupCPUWeight=");
+                        else
+                                unit_write_drop_in_private_format(u, mode, name, "StartupCPUWeight=%" PRIu64, weight);
+                }
+
+                return 1;
+
         } else if (streq(name, "CPUShares")) {
                 uint64_t shares;
 
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 396f847213..edcfa6fa1b 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -121,6 +121,8 @@ $1.KillSignal,                   config_parse_signal,                0,
 m4_define(`CGROUP_CONTEXT_CONFIG_ITEMS',
 `$1.Slice,                       config_parse_unit_slice,            0,                             0
 $1.CPUAccounting,                config_parse_bool,                  0,                             offsetof($1, cgroup_context.cpu_accounting)
+$1.CPUWeight,                    config_parse_cpu_weight,            0,                             offsetof($1, cgroup_context.cpu_weight)
+$1.StartupCPUWeight,             config_parse_cpu_weight,            0,                             offsetof($1, cgroup_context.startup_cpu_weight)
 $1.CPUShares,                    config_parse_cpu_shares,            0,                             offsetof($1, cgroup_context.cpu_shares)
 $1.StartupCPUShares,             config_parse_cpu_shares,            0,                             offsetof($1, cgroup_context.startup_cpu_shares)
 $1.CPUQuota,                     config_parse_cpu_quota,             0,                             offsetof($1, cgroup_context)
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index 420f368689..4ad6c4d79b 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -2851,6 +2851,34 @@ int config_parse_unit_slice(
 
 DEFINE_CONFIG_PARSE_ENUM(config_parse_device_policy, cgroup_device_policy, CGroupDevicePolicy, "Failed to parse device policy");
 
+int config_parse_cpu_weight(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        uint64_t *weight = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        r = cg_weight_parse(rvalue, weight);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r, "CPU weight '%s' invalid. Ignoring.", rvalue);
+                return 0;
+        }
+
+        return 0;
+}
+
 int config_parse_cpu_shares(
                 const char *unit,
                 const char *filename,
@@ -4191,6 +4219,7 @@ void unit_dump_config_items(FILE *f) {
                 { config_parse_address_families,      "FAMILIES" },
 #endif
                 { config_parse_cpu_shares,            "SHARES" },
+                { config_parse_cpu_weight,            "WEIGHT" },
                 { config_parse_memory_limit,          "LIMIT" },
                 { config_parse_device_allow,          "DEVICE" },
                 { config_parse_device_policy,         "POLICY" },
diff --git a/src/core/load-fragment.h b/src/core/load-fragment.h
index 213bce55a7..8b688740cf 100644
--- a/src/core/load-fragment.h
+++ b/src/core/load-fragment.h
@@ -81,6 +81,7 @@ int config_parse_syscall_errno(const char *unit, const char *filename, unsigned
 int config_parse_environ(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_pass_environ(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unit_slice(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
+int config_parse_cpu_weight(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_cpu_shares(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_memory_limit(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_tasks_max(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
diff --git a/src/core/unit.c b/src/core/unit.c
index ff7c562fba..952604e0db 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -2608,7 +2608,7 @@ int unit_serialize(Unit *u, FILE *f, FDSet *fds, bool serialize_jobs) {
                 unit_serialize_item(u, f, "assert-result", yes_no(u->assert_result));
 
         unit_serialize_item(u, f, "transient", yes_no(u->transient));
-        unit_serialize_item_format(u, f, "cpuacct-usage-base", "%" PRIu64, u->cpuacct_usage_base);
+        unit_serialize_item_format(u, f, "cpu-usage-base", "%" PRIu64, u->cpu_usage_base);
 
         if (u->cgroup_path)
                 unit_serialize_item(u, f, "cgroup", u->cgroup_path);
@@ -2824,9 +2824,9 @@ int unit_deserialize(Unit *u, FILE *f, FDSet *fds) {
 
                         continue;
 
-                } else if (streq(l, "cpuacct-usage-base")) {
+                } else if (streq(l, "cpu-usage-base") || streq(l, "cpuacct-usage-base")) {
 
-                        r = safe_atou64(v, &u->cpuacct_usage_base);
+                        r = safe_atou64(v, &u->cpu_usage_base);
                         if (r < 0)
                                 log_unit_debug(u, "Failed to parse CPU usage %s, ignoring.", v);
 
diff --git a/src/core/unit.h b/src/core/unit.h
index 47eb8d50a6..a6c69938dd 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -184,8 +184,8 @@ struct Unit {
         UnitFileState unit_file_state;
         int unit_file_preset;
 
-        /* Where the cpuacct.usage cgroup counter was at the time the unit was started */
-        nsec_t cpuacct_usage_base;
+        /* Where the cpu.stat or cpuacct.usage was at the time the unit was started */
+        nsec_t cpu_usage_base;
 
         /* Counterparts in the cgroup filesystem */
         char *cgroup_path;