+ _cleanup_free_ char *root = NULL, *value = NULL;
+ uint64_t mem, lim;
+ size_t ps;
+ long sc;
+
+ /* We return this as uint64_t in case we are running as 32bit process on a 64bit kernel with huge amounts of
+ * memory.
+ *
+ * In order to support containers nicely that have a configured memory limit we'll take the minimum of the
+ * physically reported amount of memory and the limit configured for the root cgroup, if there is any. */
+
+ sc = sysconf(_SC_PHYS_PAGES);
+ assert(sc > 0);
+
+ ps = page_size();
+ mem = (uint64_t) sc * (uint64_t) ps;
+
+ if (cg_get_root_path(&root) < 0)
+ return mem;
+
+ if (cg_get_attribute("memory", root, "memory.limit_in_bytes", &value))
+ return mem;
+
+ if (safe_atou64(value, &lim) < 0)
+ return mem;
+
+ /* Make sure the limit is a multiple of our own page size */
+ lim /= ps;
+ lim *= ps;
+
+ return MIN(mem, lim);
+}
+
+uint64_t physical_memory_scale(uint64_t v, uint64_t max) {
+ uint64_t p, m, ps, r;
+
+ assert(max > 0);
+
+ /* Returns the physical memory size, multiplied by v divided by max. Returns UINT64_MAX on overflow. On success
+ * the result is a multiple of the page size (rounds down). */
+
+ ps = page_size();
+ assert(ps > 0);
+
+ p = physical_memory() / ps;
+ assert(p > 0);
+
+ m = p * v;
+ if (m / p != v)
+ return UINT64_MAX;
+
+ m /= max;
+
+ r = m * ps;
+ if (r / ps != m)
+ return UINT64_MAX;
+
+ return r;
+}
+
+uint64_t system_tasks_max(void) {
+
+#if SIZEOF_PID_T == 4
+#define TASKS_MAX ((uint64_t) (INT32_MAX-1))
+#elif SIZEOF_PID_T == 2
+#define TASKS_MAX ((uint64_t) (INT16_MAX-1))
+#else
+#error "Unknown pid_t size"
+#endif
+
+ _cleanup_free_ char *value = NULL, *root = NULL;
+ uint64_t a = TASKS_MAX, b = TASKS_MAX;
+
+ /* Determine the maximum number of tasks that may run on this system. We check three sources to determine this
+ * limit:
+ *
+ * a) the maximum value for the pid_t type
+ * b) the cgroups pids_max attribute for the system
+ * c) the kernel's configure maximum PID value
+ *
+ * And then pick the smallest of the three */
+
+ if (read_one_line_file("/proc/sys/kernel/pid_max", &value) >= 0)
+ (void) safe_atou64(value, &a);
+
+ if (cg_get_root_path(&root) >= 0) {
+ value = mfree(value);
+
+ if (cg_get_attribute("pids", root, "pids.max", &value) >= 0)
+ (void) safe_atou64(value, &b);
+ }
+
+ return MIN3(TASKS_MAX,
+ a <= 0 ? TASKS_MAX : a,
+ b <= 0 ? TASKS_MAX : b);
+}
+
+uint64_t system_tasks_max_scale(uint64_t v, uint64_t max) {
+ uint64_t t, m;
+
+ assert(max > 0);
+
+ /* Multiply the system's task value by the fraction v/max. Hence, if max==100 this calculates percentages
+ * relative to the system's maximum number of tasks. Returns UINT64_MAX on overflow. */