How to improve my ethernet's transfer speed?

My board : DE2-115

SOPCBuilder : DE2_115_WEB_SERVER_RGMII_ENET1

NIOS II software :Simple_Socket_Server(RGMII)

Now I can transfer data to my PC in both 1000Mbps and 100Mbps mode.

But the speed is really low, and 1000Mbps and 100Mbps mode don't have any differences. The speed is about 2.1MB/s.

My codes in simple_socket_server.c are as follows.

I hope that I can get some help to raise the transfer speed.

******************************************************

********************simple_socket_server.c*****************

******************************************************

#include <stdio.h># include <string.h># include <ctype.h>

/* MicroC/OS-II definitions */# include "includes.h"

/* Simple UDP Client definitions */# include "simple_socket_server.h" # include "alt_error_handler.h"

/* Nichestack definitions */# include "ipport.h"# include "tcpport.h"# define MAXDATASIZE 1450

void SSSSimpleSocketServerTask()

{

int fd_listen;// max_socket

int fd_listen1;

int long bytes_sent;

int long bytes_recv;

int nSendBufSize=SSS_TX_BUF_SIZE;

struct sockaddr_in server_addr;

struct sockaddr_in client_addr;

fd_listen = socket(AF_INET, SOCK_STREAM, 0);

setsockopt(fd_listen,SOL_SOCKET,SO_SNDBUF,(char * )&nSendBufSize,sizeof(int));

if (fd_listen< 0)

{

alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Socket creation failed");

}

else

{

printf("Socket created");

}

server_addr.sin_family = AF_INET;

server_addr.sin_port = htons(SSS_PORT);

server_addr.sin_addr.s_addr = INADDR_ANY;

memset(&(server_addr.sin_zero), '\0', 8);

if ((bind(fd_listen,(struct sockaddr *)&server_addr,sizeof(server_addr))) < 0)

{

alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Bind failed");

}

else

{

printf("Bind is OK\n");

}

if ((listen(fd_listen,5)) < 0

{

alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Listen failed");

}

else

{

printf("Listen is OK\n");

}

int client_addrlen;

client_addrlen=sizeof(client_addr);

fd_listen1 = accept(fd_listen,(struct sockaddr *)&client_addr,&client_addrlen);

while(1)

{

if(fd_listen1<0)

{

alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Accept creation failed");

}

else

{

printf("accepted connection request\n");

}

fd_listen = fd_listen1;

break;

}

printf("Server: Sending some test data to client...\n");

char sendbuf[MAXDATASIZE] = "Bjtuxuxu Love FPGA!";

char recvbuf[200] = "";

while(1)

{

bytes_sent = send(fd_listen,sendbuf,SSS_BUF_LEN,0);//strlen(sendbuf)

}

if(bytes_sent<0)

{

alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Send failed");

}

else

{

printf("SERVER : Send is OK \n");

printf("SERVER : Bytes sent:%ld.\n",bytes_sent);

}

bytes_recv = recv(fd_listen,recvbuf,200,0);

if(bytes_recv<0)

{

alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Recv failed");

}

else

{

printf("SERVER: recv() is OK.\n");

printf("SERVER: Received data is: \"%s\"\n", recvbuf);

printf("SERVER: Bytes received: %ld.\n", bytes_recv);

}

return ;

}

******************************************************

********************simple_socket_server.c*****************

******************************************************