Add realtime scheduling calls to std.os.linux (issue #19671)

lib/std/os/linux.zig

@@ -1876,6 +1876,53 @@ pub fn fremovexattr(fd: usize, name: [*:0]const u8) usize {
     return syscall2(.fremovexattr, fd, @intFromPtr(name));
 }
 
+pub const sched_param = extern struct {
+    sched_priority: i32,
+};
+
+pub const SCHED = struct {
+    /// normal multi-user scheduling
+    pub const OTHER = 0;
+    /// FIFO realtime scheduling
+    pub const FIFO = 1;
+    /// Round-robin realtime scheduling
+    pub const RR = 2;
+    /// For "batch" style execution of processes
+    pub const BATCH = 3;
+    /// Low latency scheduling
+    pub const ISO = 4;
+    /// For running very low priority background jobs
+    pub const IDLE = 5;
+    /// Sporadic task model deadline scheduling
+    pub const DEADLINE = 6;
+    /// OR with other values to stop children from inheriting policies
+    pub const RESET_ON_FORK = 0x40000000;
+};
+
+pub fn sched_setparam(pid: pid_t, param: *const sched_param) usize {
+    return syscall2(.sched_setparam, @as(usize, @bitCast(@as(isize, pid))), @intFromPtr(param));
+}
+
+pub fn sched_getparam(pid: pid_t, param: *sched_param) usize {
+    return syscall2(.sched_getparam, @as(usize, @bitCast(@as(isize, pid))), @intFromPtr(param));
+}
+
+pub fn sched_setscheduler(pid: pid_t, policy: u32, param: *const sched_param) usize {
+    return syscall3(.sched_setscheduler, @as(usize, @bitCast(@as(isize, pid))), policy, @intFromPtr(param));
+}
+
+pub fn sched_getscheduler(pid: pid_t) usize {
+    return syscall1(.sched_getscheduler, @as(usize, @bitCast(@as(isize, pid))));
+}
+
+pub fn sched_get_priority_max(policy: u32) isize {
+    return @bitCast(syscall1(.sched_get_priority_max, policy));
+}
+
+pub fn sched_get_priority_min(policy: u32) isize {
+    return @bitCast(syscall1(.sched_get_priority_min, policy));
+}
+
 pub fn sched_yield() usize {
     return syscall0(.sched_yield);
 }