Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 192 insertions, 0 deletions

diff --git a/src/basic/limits-util.c b/src/basic/limits-util.c
new file mode 100644
index 0000000..9597c4c
--- /dev/null
+++ b/src/basic/limits-util.c
@@ -0,0 +1,192 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "cgroup-util.h"
+#include "limits-util.h"
+#include "memory-util.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "procfs-util.h"
+#include "string-util.h"
+
+uint64_t physical_memory(void) {
+        _cleanup_free_ char *root = NULL, *value = NULL;
+        uint64_t mem, lim;
+        size_t ps;
+        long sc;
+        int r;
+
+        /* We return this as uint64_t in case we are running as 32-bit process on a 64-bit 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;
+
+        r = cg_get_root_path(&root);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to determine root cgroup, ignoring cgroup memory limit: %m");
+                return mem;
+        }
+
+        r = cg_all_unified();
+        if (r < 0) {
+                log_debug_errno(r, "Failed to determine root unified mode, ignoring cgroup memory limit: %m");
+                return mem;
+        }
+        if (r > 0) {
+                r = cg_get_attribute("memory", root, "memory.max", &value);
+                if (r == -ENOENT) /* Field does not exist on the system's top-level cgroup, hence don't
+                                   * complain. (Note that it might exist on our own root though, if we live
+                                   * in a cgroup namespace, hence check anyway instead of not even
+                                   * trying.) */
+                        return mem;
+                if (r < 0) {
+                        log_debug_errno(r, "Failed to read memory.max cgroup attribute, ignoring cgroup memory limit: %m");
+                        return mem;
+                }
+
+                if (streq(value, "max"))
+                        return mem;
+        } else {
+                r = cg_get_attribute("memory", root, "memory.limit_in_bytes", &value);
+                if (r < 0) {
+                        log_debug_errno(r, "Failed to read memory.limit_in_bytes cgroup attribute, ignoring cgroup memory limit: %m");
+                        return mem;
+                }
+        }
+
+        r = safe_atou64(value, &lim);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to parse cgroup memory limit '%s', ignoring: %m", value);
+                return mem;
+        }
+        if (lim == UINT64_MAX)
+                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;
+
+        /* Shortcut two special cases */
+        if (v == 0)
+                return 0;
+        if (v == max)
+                return physical_memory();
+
+        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);
+
+        if (v > UINT64_MAX / p)
+                return UINT64_MAX;
+
+        m = p * v;
+        m /= max;
+
+        if (m > UINT64_MAX / ps)
+                return UINT64_MAX;
+
+        return m * ps;
+}
+
+uint64_t system_tasks_max(void) {
+        uint64_t a = TASKS_MAX, b = TASKS_MAX, c = TASKS_MAX;
+        _cleanup_free_ char *root = NULL;
+        int r;
+
+        /* Determine the maximum number of tasks that may run on this system. We check three sources to
+         * determine this limit:
+         *
+         * a) kernel.threads-max sysctl: the maximum number of tasks (threads) the kernel allows.
+         *
+         *    This puts a direct limit on the number of concurrent tasks.
+         *
+         * b) kernel.pid_max sysctl: the maximum PID value.
+         *
+         *    This limits the numeric range PIDs can take, and thus indirectly also limits the number of
+         *    concurrent threads. It's primarily a compatibility concept: some crappy old code used a signed
+         *    16-bit type for PIDs, hence the kernel provides a way to ensure the PIDs never go beyond
+         *    INT16_MAX by default.
+         *
+         *    Also note the weird definition: PIDs assigned will be kept below this value, which means
+         *    the number of tasks that can be created is one lower, as PID 0 is not a valid process ID.
+         *
+         * c) pids.max on the root cgroup: the kernel's configured maximum number of tasks.
+         *
+         * and then pick the smallest of the three.
+         *
+         * By default pid_max is set to much lower values than threads-max, hence the limit people come into
+         * contact with first, as it's the lowest boundary they need to bump when they want higher number of
+         * processes.
+         */
+
+        r = procfs_get_threads_max(&a);
+        if (r < 0)
+                log_debug_errno(r, "Failed to read kernel.threads-max, ignoring: %m");
+
+        r = procfs_get_pid_max(&b);
+        if (r < 0)
+                log_debug_errno(r, "Failed to read kernel.pid_max, ignoring: %m");
+        else if (b > 0)
+                /* Subtract one from pid_max, since PID 0 is not a valid PID */
+                b--;
+
+        r = cg_get_root_path(&root);
+        if (r < 0)
+                log_debug_errno(r, "Failed to determine cgroup root path, ignoring: %m");
+        else {
+                /* We'll have the "pids.max" attribute on the our root cgroup only if we are in a
+                 * CLONE_NEWCGROUP namespace. On the top-level namespace this attribute is missing, hence
+                 * suppress any message about that */
+                r = cg_get_attribute_as_uint64("pids", root, "pids.max", &c);
+                if (r < 0 && r != -ENODATA)
+                        log_debug_errno(r, "Failed to read pids.max attribute of root cgroup, ignoring: %m");
+        }
+
+        return MIN3(a, b, c);
+}
+
+uint64_t system_tasks_max_scale(uint64_t v, uint64_t max) {
+        uint64_t t, m;
+
+        /* Shortcut two special cases */
+        if (v == 0)
+                return 0;
+        if (v == max)
+                return system_tasks_max();
+
+        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. */
+
+        t = system_tasks_max();
+        assert(t > 0);
+
+        if (v > UINT64_MAX / t) /* overflow? */
+                return UINT64_MAX;
+
+        m = t * v;
+        return m / max;
+}