From 209a665ed46af4815cbdd2113594c3a530fb6916 Mon Sep 17 00:00:00 2001
From: PatricZhao <patric.zhao@intel.com>
Date: Mon, 25 Oct 2021 14:15:43 +0800
Subject: [PATCH] Add async example

---
 code/async.cpp | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 code/async.cpp

diff --git a/code/async.cpp b/code/async.cpp
new file mode 100644
index 0000000..31ef769
--- /dev/null
+++ b/code/async.cpp
@@ -0,0 +1,103 @@
+   // Copyright (C) 2020 Intel Corporation
+   
+   // SPDX-License-Identifier: MIT
+   
+   #include <CL/sycl.hpp>
+   #include <iostream>
+   using namespace sycl;
+   
+   constexpr int64_t N = 10000000;
+   
+   int main() {
+     
+     // Enable queue profiling  
+     queue my_gpu_queue(gpu_selector{}, cl::sycl::property::queue::in_order());
+   
+     std::cout << "Selected GPU device: " <<
+       my_gpu_queue.get_device().get_info<info::device::name>() << "\n";
+
+   
+     int *cpu_out    = (int*)malloc(N * sizeof(int));
+     int *host_mem   = malloc_host<int>(N, my_gpu_queue);
+     int *device_mem = malloc_device<int>(N, my_gpu_queue); 
+   
+     // Init CPU data
+     for(int64_t i = 0; i < N; i++) {
+        host_mem[i] = i % 6666;
+        cpu_out[i] = i % 6666;
+     }
+
+     float duration_cpu = 0.0;
+     float duration_gpu = 0.0;
+     float duration_total = 0.0;
+
+     std::chrono::high_resolution_clock::time_point s_cpu, e_cpu;
+     std::chrono::high_resolution_clock::time_point s_gpu, e_gpu;
+     std::chrono::high_resolution_clock::time_point s_t, e_t;
+
+      // warmup
+     /*********************************************************************/
+      for(int64_t i = 0; i < N; i++) {
+         cpu_out[i] = cpu_out[i] * 2;
+      }
+
+      my_gpu_queue.memcpy(device_mem, host_mem, N * sizeof(int)).wait();
+      my_gpu_queue.submit([&](handler& h) {
+
+       // Parallel Computation
+       h.parallel_for(range{N}, [=](id<1> item) {
+         device_mem[item] *= 2;
+       });
+
+      });
+      my_gpu_queue.wait();
+     /*********************************************************************/
+
+     printf("\n Start CPU Computation, Number of Elems = %ld \n", N);
+     
+     s_t = std::chrono::high_resolution_clock::now();
+
+     // GPU Computation
+     // submit the content to the queue for execution
+     s_gpu = std::chrono::high_resolution_clock::now();
+     auto event =  my_gpu_queue.submit([&](handler& h) {
+            // Parallel Computation      
+            h.parallel_for(range{N}, [=](id<1> item) {
+            device_mem[item] *= 2;
+            });
+         });
+ 
+     // CPU computation
+     s_cpu = std::chrono::high_resolution_clock::now();
+     for(int64_t i = 0; i < N; i++) {
+         cpu_out[i] *= 2;
+     }
+     e_cpu = std::chrono::high_resolution_clock::now();
+
+     // Testing overlapping between CPU and GPU
+     // Delay the wait() after CPU computation
+     event.wait();
+     e_gpu = std::chrono::high_resolution_clock::now();
+
+     e_t = std::chrono::high_resolution_clock::now();
+
+     duration_cpu =  std::chrono::duration<float, std::milli>(e_cpu - s_cpu).count();
+     duration_gpu =  std::chrono::duration<float, std::milli>(e_gpu - s_gpu).count();
+     duration_total =  std::chrono::duration<float, std::milli>(e_t - s_t).count();
+
+     // Copy back from GPU to CPU
+     my_gpu_queue.memcpy(host_mem, device_mem, N * sizeof(int)).wait();
+
+     printf("\n CPU Computation,   Time = %lf \n", duration_cpu);
+     printf("\n GPU Computation,   Time = %lf \n", duration_gpu);
+     printf("\n Total Computation, TIme = %lf \n", duration_total);
+
+     free(cpu_out);
+     free(host_mem, my_gpu_queue);
+     free(device_mem, my_gpu_queue);
+
+     printf("\nTask Done!\n");
+   
+     return 0;
+   }
+