Re: [bpf-next PATCH v3 3/7] bpf: sockmap sample, use fork() for send and recv

Martin KaFai Lau
2018-01-13T07:34:13Z

On Thu, Jan 11, 2018 at 09:06:54PM -0800, John Fastabend wrote:
> Currently for SENDMSG tests first send completes then recv runs. This
> does not work well for large data sizes and/or many iterations. So
> fork the recv and send handler so that we run both send and recv. In
> the future we can add a parameter to do more than a single fork of
> tx/rx.
>
> With this we can get many GBps of data which helps exercise the
> sockmap code.
>
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>
One nit.

Acked-by: Martin KaFai Lau <kafai@fb.com>

> ---
[ ... ]
> @@ -274,25 +275,50 @@ static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
>
> static int sendmsg_test(int iov_count, int iov_buf, int cnt, int verbose)
> {
> + int txpid, rxpid, err = 0;
> struct msg_stats s = {0};
> - int err;
> -
> - err = msg_loop(c1, iov_count, iov_buf, cnt, &s, true);
> - if (err) {
> - fprintf(stderr,
> - "msg_loop_tx: iov_count %i iov_buf %i cnt %i err %i\n",
> - iov_count, iov_buf, cnt, err);
> - return err;
> + int status;
> +
> + errno = 0;
> +
> + rxpid = fork();
> + if (rxpid == 0) {
> + err = msg_loop(p2, iov_count, iov_buf, cnt, &s, false);
> + if (err)
> + fprintf(stderr,
> + "msg_loop_rx: iov_count %i iov_buf %i cnt %i err %i\n",
> + iov_count, iov_buf, cnt, err);
> + fprintf(stdout, "rx_sendmsg: TX_bytes %zu RX_bytes %zu\n",
> + s.bytes_sent, s.bytes_recvd);
> + shutdown(p2, SHUT_RDWR);
> + shutdown(p1, SHUT_RDWR);
> + exit(1);
> + } else if (rxpid == -1) {
> + perror("msg_loop_rx: ");
> + return errno;
> }
>
> - msg_loop(p2, iov_count, iov_buf, cnt, &s, false);
> - if (err)
> - fprintf(stderr,
> - "msg_loop_rx: iov_count %i iov_buf %i cnt %i err %i\n",
> - iov_count, iov_buf, cnt, err);
> + txpid = fork();
> + if (txpid == 0) {
> + err = msg_loop(c1, iov_count, iov_buf, cnt, &s, true);
> + if (err)
> + fprintf(stderr,
> + "msg_loop_tx: iov_count %i iov_buf %i cnt %i err %i\n",
> + iov_count, iov_buf, cnt, err);
> + fprintf(stdout, "tx_sendmsg: TX_bytes %zu RX_bytes %zu\n",
> + s.bytes_sent, s.bytes_recvd);
> + shutdown(c1, SHUT_RDWR);
> + exit(1);
> + } else if (txpid == -1) {
> + perror("msg_loop_tx: ");
> + return errno;
> + }
>
> - fprintf(stdout, "sendmsg: TX_bytes %zu RX_bytes %zu\n",
> - s.bytes_sent, s.bytes_recvd);
> + assert(waitpid(rxpid, &status, 0) == rxpid);
> + if (!txpid)
This case won't be hit?

> + goto out;
> + assert(waitpid(txpid, &status, 0) == txpid);
> +out:
> return err;
> }
>
>