core: support percentage specifications on TasksMax=

This adds support for a TasksMax=40% syntax for specifying values relative to
the system's configured maximum number of processes. This is useful in order to
neatly subdivide the available room for tasks within containers.

1 files changed, 20 insertions, 15 deletions

diff --git a/src/shared/bus-unit-util.c b/src/shared/bus-unit-util.c
index 94ffa8af87..e63e9195f1 100644
--- a/src/shared/bus-unit-util.c
+++ b/src/shared/bus-unit-util.c
@@ -148,6 +148,26 @@ int bus_append_unit_property_assignment(sd_bus_message *m, const char *assignmen
 
                 r = sd_bus_message_append(m, "sv", field, "t", bytes);
                 goto finish;
+        } else if (streq(field, "TasksMax")) {
+                uint64_t t;
+
+                if (isempty(eq) || streq(eq, "infinity"))
+                        t = (uint64_t) -1;
+                else {
+                        r = parse_percent(eq);
+                        if (r >= 0) {
+                                r = sd_bus_message_append(m, "sv", "TasksMaxScale", "u", (uint32_t) (((uint64_t) UINT32_MAX * r) / 100U));
+                                goto finish;
+                        } else {
+                                r = safe_atou64(eq, &t);
+                                if (r < 0)
+                                        return log_error_errno(r, "Failed to parse maximum tasks specification %s", assignment);
+                        }
+
+                }
+
+                r = sd_bus_message_append(m, "sv", "TasksMax", "t", t);
+                goto finish;
         }
 
         r = sd_bus_message_append_basic(m, SD_BUS_TYPE_STRING, field);
@@ -191,21 +211,6 @@ int bus_append_unit_property_assignment(sd_bus_message *m, const char *assignmen
 
                 r = sd_bus_message_append(m, "v", "b", r);
 
-        } else if (streq(field, "TasksMax")) {
-                uint64_t n;
-
-                if (isempty(eq) || streq(eq, "infinity"))
-                        n = (uint64_t) -1;
-                else {
-                        r = safe_atou64(eq, &n);
-                        if (r < 0) {
-                                log_error("Failed to parse maximum tasks specification %s", assignment);
-                                return -EINVAL;
-                        }
-                }
-
-                r = sd_bus_message_append(m, "v", "t", n);
-
         } else if (STR_IN_SET(field, "CPUShares", "StartupCPUShares")) {
                 uint64_t u;