Did anyone do the performance test on the sniffer way of afpacket?

I'm writing a traffic sniffer and realtime-analyzer. Today I did a test on the performance of the part of writing packets. Results show that it lost packets when the speed of traffic was 200Mbps. I wonder that whether there exists problems in my codes.

Here are my codes:
```
package main
import (
"fmt"
"log"
"time"
"github.com/google/gopacket/afpacket"
"os"
"config"
"github.com/google/gopacket/pcapgo"
"github.com/google/gopacket/layers"
)

var (
snapshot_len int = 65535
promiscuous bool = true
timeout time.Duration = -1 * time.Second
buffersizeMb int =500
)
func OpenAFpacket(nic string)( *afpacket.TPacket,error){
szFrame, szBlock, numBlocks, err := afpacketComputeSize(buffersizeMb, snapshot_len, os.Getpagesize())
if err != nil {
log.Fatal(err)
}
handle, err := afpacket.NewTPacket(
afpacket.OptInterface(nic),
afpacket.OptFrameSize(szFrame),
afpacket.OptBlockSize(szBlock),
afpacket.OptNumBlocks(numBlocks),
afpacket.OptPollTimeout(timeout))
return handle,err
}

func afpacketComputeSize(targetSizeMb int, snaplen int, pageSize int) (
frameSize int, blockSize int, numBlocks int, err error) {

if snaplen < pageSize {
frameSize = pageSize / (pageSize / snaplen)
} else {
frameSize = (snaplen/pageSize + 1) * pageSize
}

blockSize = frameSize * 128
numBlocks = (targetSizeMb * 1024 * 1024) / blockSize

if numBlocks == 0 {
return 0, 0, 0, fmt.Errorf("Buffer size too small")
}
return frameSize, blockSize, numBlocks, nil
}

func main() {

var packetnum int64
h,err :=OpenAFpacket("em2")
if err !=nil{
log.Fatal(err)
}
h.TpacketVersion()
f, _ := os.Create(config.PCAP_DIR+"/testcapture.pcap")
w := pcapgo.NewWriter(f)
w.WriteFileHeader(65536, layers.LinkTypeEthernet) // new file, must do this

for{
data,ci,err := h.ZeroCopyReadPacketData()
if err!=nil{
log.Fatal(err)
}
err=w.WritePacket(ci, data)
if err!=nil{
log.Fatal(err)
}
packetnum++
//fmt.Println("packet num:",packetnum)
}
}
```