[go-nuts] about the performance of read/write binary file

i use encoding/binary package for testing the binary write/read speed, but
it reach 12MB/s at most.
What is the fastest way to read/write binary file using go?

source code:

type Action struct {
U1 uint64
U2 uint64
U3 uint64
}

f, _ := os.Create("test.dat")
defer f.Close()

w := bufio.NewWriter(f)
var action Action
for {
binary.Write(w, binary.LittleEndian, &action)
}

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