Add support for SCHED_DEADLINE flags

src/lib.rs

@@ -182,7 +182,7 @@ pub enum ThreadPriority {
     /// the nanoseconds for runtime, deadline, and period. Please note that the
     /// kernel enforces runtime <= deadline <= period.
     #[cfg(target_os = "linux")]
-    Deadline(u64, u64, u64),
+    Deadline(u64, u64, u64, Option<DeadlineFlags>),
     /// Holds a value representing the maximum possible priority.
     /// Should be used with caution, it solely depends on the target
     /// os where the program is going to be running on, how it will

src/unix.rs

@@ -103,6 +103,17 @@ impl RealtimeThreadSchedulePolicy {
     }
 }
 
+/// Flags for controlling Deadline scheduling behavior.
+#[derive(Debug, Clone, Copy, Ord, PartialEq, Eq, PartialOrd, Hash)]
+pub enum DeadlineFlags {
+    /// Children created by fork will not inhered privileged scheduling policies.
+    ResetOnFork = 0x01,
+    /// The thread may reclaim bandwidth that is unused by another realtime thread.
+    Reclaim = 0x02,
+    /// Request to be sent SIGXCPU when this thread overruns its deadline.
+    DeadlineOverrun = 0x04,
+}
+
 /// Normal (usual) schedule policies
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub enum NormalThreadSchedulePolicy {
@@ -220,7 +231,7 @@ impl ThreadPriority {
                 _ => Ok(0),
             },
             #[cfg(target_os = "linux")]
-            ThreadPriority::Deadline(_, _, _) => Err(Error::Priority(
+            ThreadPriority::Deadline(_, _, _, _) => Err(Error::Priority(
                 "Deadline is non-POSIX and cannot be converted.",
             )),
         };
@@ -313,8 +324,8 @@ pub fn set_thread_schedule_policy(
             // SCHED_DEADLINE policy requires its own syscall
             #[cfg(target_os = "linux")]
             ThreadSchedulePolicy::Realtime(RealtimeThreadSchedulePolicy::Deadline) => {
-                let (runtime, deadline, period) = match priority {
-                    ThreadPriority::Deadline(r, d, p) => (r, d, p),
+                let (runtime, deadline, period, flags) = match priority {
+                    ThreadPriority::Deadline(r, d, p, f) => (r, d, p, f),
                     _ => {
                         return Err(Error::Priority(
                             "Deadline policy given without deadline priority.",
@@ -325,20 +336,17 @@ pub fn set_thread_schedule_policy(
                 let sched_attr = SchedAttr {
                     size: std::mem::size_of::<SchedAttr>() as u32,
                     sched_policy: policy.to_posix() as u32,
-
+                    sched_flags: match flags {
+                        None => 0,
+                        Some(flags) => flags as u64,
+                    },
                     sched_runtime: runtime as u64,
                     sched_deadline: deadline as u64,
                     sched_period: period as u64,
 
                     ..Default::default()
                 };
-                libc::syscall(
-                    libc::SYS_sched_setattr,
-                    tid,
-                    &sched_attr as *const _,
-                    // we are not setting SCHED_FLAG_RECLAIM nor SCHED_FLAG_DL_OVERRUN
-                    0,
-                ) as i32
+                libc::syscall(libc::SYS_sched_setattr, tid, &sched_attr as *const _, 0) as i32
             }
             _ => libc::pthread_setschedparam(
                 native,
@@ -543,7 +551,12 @@ mod tests {
 
         assert!(set_thread_priority_and_policy(
             0, // current thread
-            ThreadPriority::Deadline(1 * 10_u64.pow(6), 10 * 10_u64.pow(6), 100 * 10_u64.pow(6)),
+            ThreadPriority::Deadline(
+                1 * 10_u64.pow(6),
+                10 * 10_u64.pow(6),
+                100 * 10_u64.pow(6),
+                None
+            ),
             ThreadSchedulePolicy::Realtime(RealtimeThreadSchedulePolicy::Deadline)
         )
         .is_ok());
@@ -569,4 +582,48 @@ mod tests {
             assert_eq!(sched_attr.sched_period, 100 * 10_u64.pow(6));
         }
     }
+
+    #[test]
+    #[cfg(target_os = "linux")]
+    fn set_deadline_flags() {
+        // allow the identity operation for clarity
+        #![allow(clippy::identity_op)]
+
+        assert!(set_thread_priority_and_policy(
+            0, // current thread
+            ThreadPriority::Deadline(
+                1 * 10_u64.pow(6),
+                10 * 10_u64.pow(6),
+                100 * 10_u64.pow(6),
+                Some(DeadlineFlags::DeadlineOverrun)
+            ),
+            ThreadSchedulePolicy::Realtime(RealtimeThreadSchedulePolicy::Deadline)
+        )
+        .is_ok());
+
+        // now we check the return values
+        unsafe {
+            let mut sched_attr = SchedAttr::default();
+            let ret = libc::syscall(
+                libc::SYS_sched_getattr,
+                0, // current thread
+                &mut sched_attr as *mut _,
+                std::mem::size_of::<SchedAttr>() as u32,
+                0, // flags must be 0
+            );
+
+            assert!(ret >= 0);
+            assert_eq!(
+                sched_attr.sched_policy,
+                RealtimeThreadSchedulePolicy::Deadline.to_posix() as u32
+            );
+            assert_eq!(sched_attr.sched_runtime, 1 * 10_u64.pow(6));
+            assert_eq!(sched_attr.sched_deadline, 10 * 10_u64.pow(6));
+            assert_eq!(sched_attr.sched_period, 100 * 10_u64.pow(6));
+            assert_eq!(
+                sched_attr.sched_flags,
+                DeadlineFlags::DeadlineOverrun as u64
+            )
+        }
+    }
 }