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main.go
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/
main.go
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package main
import (
"flag"
"fmt"
"os"
"time"
"github.com/edsrzf/mmap-go"
)
func main() {
chunkSize := flag.Int("chunk-size", os.Getpagesize(), "Chunk size to use")
size := flag.Int("size", os.Getpagesize()*1024*1024, "Amount of bytes to read")
flag.Parse()
inputFile, err := os.CreateTemp("", "")
if err != nil {
panic(err)
}
defer func() {
_ = inputFile.Close()
_ = os.Remove(inputFile.Name())
}()
if err := inputFile.Truncate(int64(*size)); err != nil {
panic(err)
}
b, err := mmap.MapRegion(inputFile, *size, mmap.RDWR, 0, 0)
if err != nil {
panic(err)
}
defer b.Unmap()
p := make([]byte, *chunkSize)
beforeRead := time.Now()
for i := 0; i < *size / *chunkSize; i++ {
copy(p, b[i**chunkSize:])
}
afterRead := time.Since(beforeRead)
fmt.Println(float64(*size) / (1024 * 1024) / afterRead.Seconds())
}