check out networking/e100.txt
On Thu, 2003-05-15 at 15:54, Corey Minyard wrote:
> I'm seeing an odd thing with the e100 driver. It seems to be this way
> with the 2.4 series and with 2.5.68, and I couldn't find anything with a
> search.
>
> I've attached a small program to measure latency of round-trip time on
> UDP. If I send 85-byte packets between two of my machines, I get 170us
> round-trip latency. If I send 86-byte packets, I get 1329us latency.
> This seems quite odd. If I test on the eepro100 driver, I get expected
> linear increase in round-trip time as the packet size increases, and it
> never gets close to 1300us.
>
> To run the program, do:
>
> ./ip_lat -s <port>
>
> on one machine to run the server, and then do
>
> ./ip_lat <server IP> <port> 1000 85
>
> to send 1000 85-byte packets from another machine. Change the 85 to 86
> to see the latency go up.
>
> -Corey
>
> ______________________________________________________________________
>
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <netinet/in.h>
> #include <sys/poll.h>
> #include <sys/time.h>
> #include <fcntl.h>
> #include <netdb.h>
> #include <malloc.h>
> #include <errno.h>
> #include <popt.h>
>
> static int server;
>
> struct poptOption poptOpts[]=
> {
> {
> "server",
> 's',
> POPT_ARG_NONE,
> NULL,
> 's',
> "Enable the server",
> ""
> },
> POPT_AUTOHELP
> {
> NULL,
> 0,
> 0,
> NULL,
> 0
> }
> };
>
> void
> do_server(int port)
> {
> int fd;
> char buffer[2048];
> struct sockaddr addr;
> struct sockaddr_in ipaddr;
> socklen_t addrlen;
> size_t len;
> int rv;
>
> fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
> if (fd == -1) {
> perror("Could not bind to port");
> exit(1);
> }
>
> ipaddr.sin_family = AF_INET;
> ipaddr.sin_port = htons(port);
> ipaddr.sin_addr.s_addr = INADDR_ANY;
>
> rv = bind(fd, (struct sockaddr *) &ipaddr, sizeof(ipaddr));
> if (rv) {
> perror("Could not bind to port");
> exit(1);
> }
>
> for (;;) {
> addrlen = sizeof(addr);
> len = recvfrom(fd, buffer, sizeof(buffer), 0, &addr, &addrlen);
> if (len > 0) {
> rv = sendto(fd, buffer, len, 0, &addr, addrlen);
> if (rv == -1)
> perror("error in sendto");
> } else {
> perror("Error in recvfrom");
> }
> }
> }
>
> static long
> diff_timeval(struct timeval *left,
> struct timeval *right)
> {
> if ( (left->tv_sec < right->tv_sec)
> || ( (left->tv_sec == right->tv_sec)
> && (left->tv_usec < right->tv_usec)))
> {
> /* If left < right, just force to zero, don't allow negative
> numbers. */
> return 0;
> }
>
> return (((left->tv_sec - right->tv_sec) * 1000000)
> + (left->tv_usec - right->tv_usec));
> }
>
> static long
> average(long *data, int size, long *max, long *min)
> {
> int i;
> long rv = 0;
>
> *max = LONG_MIN;
> *min = LONG_MAX;
> for (i=0; i<size; i++) {
> if (data[i] < 0)
> continue;
> if (data[i] > *max)
> *max = data[i];
> if (data[i] < *min)
> *min = data[i];
> rv += data[i];
> }
>
> return (rv / size);
> }
>
> void do_client(struct in_addr *dest_addr, int port, int count, int size)
> {
> int fd;
> struct sockaddr_in ipaddr;
> struct sockaddr addr;
> socklen_t addrlen;
> int rv;
> int i;
> size_t len;
> char buffer[2048];
> char buffer2[2048];
> long *times;
> long avg, max, min;
> int curr_port;
>
> times = malloc(sizeof(long) * count);
> if (!times) {
> fprintf(stderr, "Out of memory\n");
> exit(1);
> }
>
> fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
> if (fd == -1) {
> fprintf(stderr, "Out of memory\n");
> exit(1);
> }
>
> curr_port = 1000;
> do {
> curr_port++;
> ipaddr.sin_family = AF_INET;
> ipaddr.sin_port = htons(curr_port);
> ipaddr.sin_addr.s_addr = INADDR_ANY;
>
> rv = bind(fd, (struct sockaddr *) &ipaddr, sizeof(ipaddr));
> } while ((curr_port < 65536) && (rv == -1));
>
> ipaddr.sin_family = AF_INET;
> ipaddr.sin_port = htons(port);
> ipaddr.sin_addr = *dest_addr;
>
> for (i=0; i<size; i++) {
> buffer[i] = i;
> }
>
> for (i=0; i<count; i++) {
> struct timeval start_time;
> struct timeval end_time;
> struct timeval wait_time;
> fd_set read_set;
>
> times[i] = -1;
>
> FD_ZERO(&read_set);
> FD_SET(fd, &read_set);
> wait_time.tv_sec = 2;
> wait_time.tv_usec = 0;
>
> gettimeofday(&start_time, NULL);
> rv = sendto(fd, buffer, size, 0,
> (struct sockaddr *) &ipaddr, sizeof(ipaddr));
> if (rv == -1) {
> perror("Error in sendto");
> continue;
> }
> retry:
> rv = select(fd+1, &read_set, NULL, NULL, &wait_time);
> gettimeofday(&end_time, NULL);
> if (rv == -1) {
> if (errno == EINTR)
> goto retry;
> perror("Error in select");
> continue;
> }
> if (rv == 0) {
> fprintf(stderr, "Timeout waiting for response %d\n", i);
> continue;
> }
>
> addrlen = sizeof(addr);
> len = recvfrom(fd, buffer2, sizeof(buffer2), 0, &addr, &addrlen);
> if (rv == -1) {
> perror("Error in recvfrom");
> continue;
> }
>
> if (len != size) {
> fprintf(stderr, "Invalid length in response to buffer %d,"
> " waiting more\n", i);
> goto retry;
> }
> if (memcmp(buffer, buffer2, size) != 0) {
> fprintf(stderr, "Invalid data in response to buffer %d,"
> " waiting more\n", i);
> goto retry;
> }
>
> times[i] = diff_timeval(&end_time, &start_time);
> }
>
> avg = average(times, count, &max, &min);
> printf("Average: %ldus, Max: %ldus, Min: %ldus\n", avg, max, min);
> }
>
> int
> main(int argc, const char *argv[])
> {
> int o;
> struct hostent *ent;
> struct in_addr addr;
> int port;
> int count;
> int size;
>
> poptContext poptCtx = poptGetContext("ip_lat", argc, argv, poptOpts,0);
>
> while (( o = poptGetNextOpt(poptCtx)) >= 0)
> {
> switch( o )
> {
> case 's':
> server = 1;
> break;
>
> default:
> poptPrintUsage(poptCtx, stderr, 0);
> exit(1);
> }
> }
>
> argv = poptGetArgs(poptCtx);
>
> if (!argv) {
> fprintf(stderr, "Not enough arguments\n");
> exit(1);
> }
>
> for (argc=0; argv[argc]!= NULL; argc++)
> ;
>
> if ((server && (argc < 1)) || (!server && (argc < 4))) {
> fprintf(stderr, "Not enough arguments\n");
> exit(1);
> }
>
> if (server) {
> port = atoi(argv[0]);
> do_server(port);
> } else {
> ent = gethostbyname(argv[0]);
> if (!ent) {
> fprintf(stderr, "gethostbyname failed: %s\n", strerror(h_errno));
> exit(1);
> }
> memcpy(&addr, ent->h_addr_list[0], ent->h_length);
> port = atoi(argv[1]);
>
> count = atoi(argv[2]);
> size = atoi(argv[3]);
> do_client(&addr, port, count, size);
> }
>
> return 0;
> }
-
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