lib/mmap: library to do memory allocation with anonymous memory maps

lib/mmap/mmap_test.go

@@ -0,0 +1,99 @@
+package mmap
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// Constants to control the benchmarking
+const (
+	maxAllocs = 16 * 1024
+)
+
+func TestAllocFree(t *testing.T) {
+	const Size = 4096
+
+	b := MustAlloc(Size)
+	assert.Equal(t, Size, len(b))
+
+	// check we can write to all the memory
+	for i := range b {
+		b[i] = byte(i)
+	}
+
+	// Now free the memory
+	MustFree(b)
+}
+
+func BenchmarkAllocFree(b *testing.B) {
+	for _, dirty := range []bool{false, true} {
+		for size := 4096; size <= 32*1024*1024; size *= 2 {
+			b.Run(fmt.Sprintf("%dk,dirty=%v", size>>10, dirty), func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					mem := MustAlloc(size)
+					if dirty {
+						mem[0] ^= 0xFF
+					}
+					MustFree(mem)
+				}
+			})
+		}
+	}
+}
+
+// benchmark the time alloc/free takes with lots of allocations already
+func BenchmarkAllocFreeWithLotsOfAllocations(b *testing.B) {
+	const size = 4096
+	alloc := func(n int) (allocs [][]byte) {
+		for i := 0; i < n; i++ {
+			mem := MustAlloc(size)
+			mem[0] ^= 0xFF
+			allocs = append(allocs, mem)
+		}
+		return allocs
+	}
+	free := func(allocs [][]byte) {
+		for _, mem := range allocs {
+			MustFree(mem)
+		}
+	}
+	for preAllocs := 1; preAllocs <= maxAllocs; preAllocs *= 2 {
+		allocs := alloc(preAllocs)
+		b.Run(fmt.Sprintf("%d", preAllocs), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				mem := MustAlloc(size)
+				mem[0] ^= 0xFF
+				MustFree(mem)
+			}
+		})
+		free(allocs)
+	}
+}
+
+// benchmark the time alloc/free takes for lots of allocations
+func BenchmarkAllocFreeForLotsOfAllocations(b *testing.B) {
+	const size = 4096
+	alloc := func(n int) (allocs [][]byte) {
+		for i := 0; i < n; i++ {
+			mem := MustAlloc(size)
+			mem[0] ^= 0xFF
+			allocs = append(allocs, mem)
+		}
+		return allocs
+	}
+	free := func(allocs [][]byte) {
+		for _, mem := range allocs {
+			MustFree(mem)
+		}
+	}
+	for preAllocs := 1; preAllocs <= maxAllocs; preAllocs *= 2 {
+		b.Run(fmt.Sprintf("%d", preAllocs), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				allocs := alloc(preAllocs)
+				free(allocs)
+			}
+		})
+	}
+}