core: add support for the "pids" cgroup controller

This adds support for the new "pids" cgroup controller of 4.3 kernels.
It allows accounting the number of tasks in a cgroup and enforcing
limits on it.

This adds two new setting TasksAccounting= and TasksMax= to each unit,
as well as a gloabl option DefaultTasksAccounting=.

This also updated "cgtop" to optionally make use of the new
kernel-provided accounting.

systemctl has been updated to show the number of tasks for each service
if it is available.

This patch also adds correct support for undoing memory limits for units
using a MemoryLimit=infinity syntax. We do the same for TasksMax= now
and hence keep things in sync here.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/core/main.c b/src/core/main.c
index c9657505c3..200fe740da 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -114,6 +114,7 @@ static FILE* arg_serialization = NULL;
 static bool arg_default_cpu_accounting = false;
 static bool arg_default_blockio_accounting = false;
 static bool arg_default_memory_accounting = false;
+static bool arg_default_tasks_accounting = false;
 
 static void nop_handler(int sig) {}
 
@@ -676,6 +677,7 @@ static int parse_config_file(void) {
                 { "Manager", "DefaultCPUAccounting",      config_parse_bool,             0, &arg_default_cpu_accounting            },
                 { "Manager", "DefaultBlockIOAccounting",  config_parse_bool,             0, &arg_default_blockio_accounting        },
                 { "Manager", "DefaultMemoryAccounting",   config_parse_bool,             0, &arg_default_memory_accounting         },
+                { "Manager", "DefaultTasksAccounting",    config_parse_bool,             0, &arg_default_tasks_accounting          },
                 {}
         };
 
@@ -704,6 +706,7 @@ static void manager_set_defaults(Manager *m) {
         m->default_cpu_accounting = arg_default_cpu_accounting;
         m->default_blockio_accounting = arg_default_blockio_accounting;
         m->default_memory_accounting = arg_default_memory_accounting;
+        m->default_tasks_accounting = arg_default_tasks_accounting;
 
         manager_set_default_rlimits(m, arg_default_rlimit);
         manager_environment_add(m, NULL, arg_default_environment);