golang几种文件读取方式的效率问题

package main 
 
import( 
    "fmt" 
    "os" 
    "flag" 
    "io" 
    "io/ioutil" 
    "bufio" 
    "time" 
) 
 
func read1(path string){ 
    fi,err := os.Open(path) 
    if err != nil{ 
        panic(err) 
    } 
    defer fi.Close() 
 
  //  chunks := make([]byte,1024,1024) 
    buf := make([]byte,1024) 
    for{ 
        n,err := fi.Read(buf) 
        if err != nil && err != io.EOF{panic(err)} 
        if 0 ==n {break} 
//        chunks=append(chunks,buf[:n]...) 
        // fmt.Println(string(buf[:n])) 
    } 
} 
 
func read2(path string){ 
    fi,err := os.Open(path) 
    if err != nil{panic(err)} 
    defer fi.Close() 
    r := bufio.NewReader(fi) 
     
//   chunks := make([]byte,1024,1024) 
      
    buf := make([]byte,1024) 
    for{ 
        n,err := r.Read(buf) 
        if err != nil && err != io.EOF{panic(err)} 
        if 0 ==n {break} 
//        chunks=append(chunks,buf[:n]...) 
        // fmt.Println(string(buf[:n])) 
    } 
} 
 
func read3(path string){ 
    fi,err := os.Open(path) 
    if err != nil{panic(err)} 
    defer fi.Close() 
    _,err = ioutil.ReadAll(fi) 
    // fmt.Println(string(fd)) 
} 
 
func main(){ 
    
    flag.Parse() 
    file := flag.Arg(0) 
    start := time.Now() 
    read1(file) 
    t1 := time.Now() 
    fmt.Printf("Cost time %v\n",t1.Sub(start)) 
    read2(file) 
    t2 := time.Now() 
    fmt.Printf("Cost time %v\n",t2.Sub(t1)) 
    read3(file) 
    t3 := time.Now() 
    fmt.Printf("Cost time %v\n",t3.Sub(t2)) 
} 

正确结论是
bufio > ioutil > file.Read