Implement hybrid Tausworthe + LCG psuedo random number generator in metal

candle-core/benches/random.rs

@@ -0,0 +1,41 @@
+use candle_core::{DType, Device, Tensor};
+use criterion::{black_box, criterion_group, criterion_main, Criterion, Throughput};
+use std::time::Instant;
+
+fn run(a: &Tensor) {
+    a.rand_like(0.0, 1.0).unwrap();
+}
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let b = 1;
+
+    let rows = 2048;
+    let cols = 2048;
+
+    let device = Device::new_metal(0).unwrap();
+    let dtype = DType::F32;
+    let tensor = Tensor::zeros((b, rows, cols), dtype, &device).unwrap();
+
+    let flops = b * rows * cols;
+
+    let mut group = c.benchmark_group("random_metal");
+    group.throughput(Throughput::Bytes(flops as u64));
+    group.bench_function("iter", move |benches| {
+        benches.iter_custom(|iters| {
+            let start = Instant::now();
+            for _i in 0..iters {
+                run(black_box(&tensor));
+            }
+            if let Device::Metal(device) = &device {
+                device.wait_until_completed().unwrap();
+            } else {
+                panic!("Expected metal device");
+            }
+            start.elapsed()
+        })
+    });
+    group.finish();
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);