Mod: finish homework

main.cpp

@@ -4,36 +4,55 @@
 #include <cmath>
 #include <numeric>
 #include <algorithm>
+#include <tbb/parallel_for.h>
+#include <tbb/parallel_reduce.h>
+#include <tbb/parallel_scan.h>
+#include <mutex>
 #include "ticktock.h"
 
 // TODO: 并行化所有这些 for 循环
 
 template <class T, class Func>
 std::vector<T> fill(std::vector<T> &arr, Func const &func) {
     TICK(fill);
-    for (size_t i = 0; i < arr.size(); i++) {
-        arr[i] = func(i);
-    }
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, arr.size()),
+        [&](tbb::blocked_range<size_t> r) {
+            for (size_t i = r.begin(); i < r.end(); ++i) {
+                arr[i] = func(i);
+            }
+        });
     TOCK(fill);
     return arr;
 }
 
 template <class T>
 void saxpy(T a, std::vector<T> &x, std::vector<T> const &y) {
     TICK(saxpy);
-    for (size_t i = 0; i < x.size(); i++) {
-       x[i] = a * x[i] + y[i];
-    }
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, x.size()), 
+        [&](tbb::blocked_range<size_t> r) {
+            for ( size_t i = r.begin(); i < r.end(); ++i) {
+                x[i] = a * x[i] + y[i];
+            }
+        });
     TOCK(saxpy);
 }
 
 template <class T>
 T sqrtdot(std::vector<T> const &x, std::vector<T> const &y) {
     TICK(sqrtdot);
     T ret = 0;
-    for (size_t i = 0; i < std::min(x.size(), y.size()); i++) {
-        ret += x[i] * y[i];
-    }
+    ret = tbb::parallel_reduce(
+        tbb::blocked_range<size_t>(0, std::min(x.size(), y.size())),
+        (T)0,
+        [&](tbb::blocked_range<size_t> r, T local_res) {
+            for ( size_t i = r.begin(); i < r.end(); ++i ) {
+                local_res += x[i] * y[i];
+            }
+            return local_res;
+        },
+        []( T x, T y) {
+            return x + y;
+        });
     ret = std::sqrt(ret);
     TOCK(sqrtdot);
     return ret;
@@ -43,10 +62,21 @@ template <class T>
 T minvalue(std::vector<T> const &x) {
     TICK(minvalue);
     T ret = x[0];
-    for (size_t i = 1; i < x.size(); i++) {
-        if (x[i] < ret)
-            ret = x[i];
-    }
+    ret = tbb::parallel_reduce(
+        tbb::blocked_range<size_t>(1, x.size()),
+        x[0],
+        [&] (tbb::blocked_range<size_t> r, T local_res) {
+            for ( size_t i = r.begin(); i < r.end(); ++i) {
+                if ( x[i] < local_res) {
+                    local_res = x[i];
+                }
+            }
+            return local_res;
+        },
+        [&] (T x, T y) {
+            return x < y ? x : y;
+        }
+    );
     TOCK(minvalue);
     return ret;
 }
@@ -55,14 +85,25 @@ template <class T>
 std::vector<T> magicfilter(std::vector<T> const &x, std::vector<T> const &y) {
     TICK(magicfilter);
     std::vector<T> res;
-    for (size_t i = 0; i < std::min(x.size(), y.size()); i++) {
-        if (x[i] > y[i]) {
-            res.push_back(x[i]);
-        } else if (y[i] > x[i] && y[i] > 0.5f) {
-            res.push_back(y[i]);
-            res.push_back(x[i] * y[i]);
+    std::mutex mtx;
+    res.reserve( 2 * std::min(x.size(), y.size()));
+    tbb::parallel_for(
+        tbb::blocked_range<size_t>(0, std::min(x.size(), y.size())),
+        [&] (tbb::blocked_range<size_t> r) {
+            std::vector<T> tmp_vec;
+            for (size_t i = r.begin(); i < r.end(); i++) {
+                if (x[i] > y[i]) {
+                    tmp_vec.push_back(x[i]);
+                } else if (y[i] > x[i] && y[i] > 0.5f) {
+                    tmp_vec.push_back(y[i]);
+                    tmp_vec.push_back(x[i] * y[i]);
+                }
+            }
+
+            std::lock_guard lck{mtx};
+            std::copy(tmp_vec.begin(), tmp_vec.end(), std::back_inserter(res));
         }
-    }
+    );
     TOCK(magicfilter);
     return res;
 }
@@ -71,10 +112,24 @@ template <class T>
 T scanner(std::vector<T> &x) {
     TICK(scanner);
     T ret = 0;
-    for (size_t i = 0; i < x.size(); i++) {
-        ret += x[i];
-        x[i] = ret;
-    }
+    // for (size_t i = 0; i < x.size(); i++) {
+    //     ret += x[i];
+    //     x[i] = ret;
+    // }
+    ret = tbb::parallel_scan(
+        tbb::blocked_range<size_t>(0, x.size()),
+        (T)0,
+        [&] (tbb::blocked_range<size_t> r, T local_res, auto is_final) {
+            for (size_t i = r.begin(); i < r.end(); i++) {
+                local_res += x[i];
+                if (is_final) x[i] = local_res;
+            }
+            return local_res;
+        },
+        [] (T x, T y) {
+            return  x + y;
+        }
+    );
     TOCK(scanner);
     return ret;
 }
@@ -100,3 +155,28 @@ int main() {
 
     return 0;
 }
+// Before
+    // fill: 1.23536s
+    // fill: 1.25023s
+    // saxpy: 0.048762s
+    // sqrtdot: 0.086141s
+    // 5165.4
+    // minvalue: 0.07746s
+    // -1.11803
+    // magicfilter: 0.426949s
+    // 55924034
+    // scanner: 0.080046s
+    // 5.28566e+07
+
+// After Modified
+    // fill: 0.256878s
+    // fill: 0.264094s
+    // saxpy: 0.03981s
+    // sqrtdot: 1.18658s
+    // 5792.62
+    // minvalue: 0.01506s
+    // -1.11803
+    // magicfilter: 0.183792s
+    // 55924034
+    // scanner: 0.032603s
+    // 5.28591e+07

run.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
 set -e
-cmake -B build
+cmake -B build -S . -DCMAKE_TOOLCHAIN_FILE=/Users/yangzhikai/farewell/cpp_review/vcpkg/scripts/buildsystems/vcpkg.cmake
 cmake --build build
 build/main