mit-ocw

commit a7a70c75b0fb0e1d6832fd65e9590aa83a491fa0
parent b2a4f54514156be7f3690a300b43ee16c50b3431
Author: Andrew Laack <andrew@laack.co>
Date:   Wed, 13 May 2026 02:36:30 -0500

Parallel

Diffstat:
A
6.172-perf-engineering/mat-mul/mat_mul_parallel.go
 | 
66
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 66 insertions(+), 0 deletions(-)
diff --git a/6.172-perf-engineering/mat-mul/mat_mul_parallel.go b/6.172-perf-engineering/mat-mul/mat_mul_parallel.go
@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"sync"
+	"time"
+)
+
+const n = 400
+
+func randInit(arr [n][n]float32) [n][n]float32 {
+
+	for i := range len(arr) {
+		for j := range len(arr[i]) {
+			arr[i][j] = rand.Float32()
+		}
+	}
+
+	return arr
+
+}
+
+func compute(A *[n][n]float32, B *[n][n]float32, C *[n][n]float32, i int, wg *sync.WaitGroup) {
+
+	for k := range B {
+		for j := range B {
+			C[i][j] += A[i][k] * B[k][j]
+		}
+	}
+
+	wg.Done()
+}
+
+func main(){
+
+
+	A := [n][n]float32{}
+	B := [n][n]float32{}
+	C := [n][n]float32{}
+
+
+	A = randInit(A)
+	B = randInit(B)
+
+	start := time.Now()
+
+	var wg sync.WaitGroup
+
+	for i := range A {
+		wg.Add(1)
+		go compute(&A, &B, &C, i, &wg)
+	}
+
+	wg.Wait()
+
+	end := time.Now()
+
+	fmt.Println(end.Sub(start).Seconds())
+}
+
+// This runs in:
+
+// 1: 0.013814715
+// 2: 0.015052904
+// 3: 0.013208566