netdev - Re: [bpf-next PATCH v2 3/7] bpf: sockmap sample, use fork() for send and recv

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Date:   Thu, 11 Jan 2018 19:57:18 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     borkmann@...earbox.net, ast@...nel.org, netdev@...r.kernel.org
Subject: Re: [bpf-next PATCH v2 3/7] bpf: sockmap sample, use fork() for send
 and recv

On 01/11/2018 01:08 PM, Martin KaFai Lau wrote:
> On Wed, Jan 10, 2018 at 10:39:37AM -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@...il.com>
>> ---

[...]

>>  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: ");
>> +		err = errno;
> Bail out here instead of continuing the tx side?
> 

Sure makes sense. No point in running the TX side here I guess.