1 files changed, 39 insertions, 0 deletions
diff --git a/third_party/rust/nix/test/test_sched.rs b/third_party/rust/nix/test/test_sched.rs
new file mode 100644
index 0000000000..c52616b8bb
--- /dev/null
+++ b/third_party/rust/nix/test/test_sched.rs
@@ -0,0 +1,39 @@
+use nix::sched::{sched_getaffinity, sched_getcpu, sched_setaffinity, CpuSet};
+use nix::unistd::Pid;
+
+#[test]
+fn test_sched_affinity() {
+    // If pid is zero, then the mask of the calling process is returned.
+    let initial_affinity = sched_getaffinity(Pid::from_raw(0)).unwrap();
+    let mut at_least_one_cpu = false;
+    let mut last_valid_cpu = 0;
+    for field in 0..CpuSet::count() {
+        if initial_affinity.is_set(field).unwrap() {
+            at_least_one_cpu = true;
+            last_valid_cpu = field;
+        }
+    }
+    assert!(at_least_one_cpu);
+
+    // Now restrict the running CPU
+    let mut new_affinity = CpuSet::new();
+    new_affinity.set(last_valid_cpu).unwrap();
+    sched_setaffinity(Pid::from_raw(0), &new_affinity).unwrap();
+
+    // And now re-check the affinity which should be only the one we set.
+    let updated_affinity = sched_getaffinity(Pid::from_raw(0)).unwrap();
+    for field in 0..CpuSet::count() {
+        // Should be set only for the CPU we set previously
+        assert_eq!(
+            updated_affinity.is_set(field).unwrap(),
+            field == last_valid_cpu
+        )
+    }
+
+    // Now check that we're also currently running on the CPU in question.
+    let cur_cpu = sched_getcpu().unwrap();
+    assert_eq!(cur_cpu, last_valid_cpu);
+
+    // Finally, reset the initial CPU set
+    sched_setaffinity(Pid::from_raw(0), &initial_affinity).unwrap();
+}