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Message-ID: <20161118181227.41333853@redhat.com>
Date: Fri, 18 Nov 2016 18:12:27 +0100
From: Jesper Dangaard Brouer <brouer@...hat.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Rick Jones <rick.jones2@....com>, netdev@...r.kernel.org,
Saeed Mahameed <saeedm@...lanox.com>,
Tariq Toukan <tariqt@...lanox.com>, brouer@...hat.com
Subject: Re: Netperf UDP issue with connected sockets
On Thu, 17 Nov 2016 13:44:02 -0800
Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Thu, 2016-11-17 at 22:19 +0100, Jesper Dangaard Brouer wrote:
>
> >
> > Maybe you can share your udp flood "udpsnd" program source?
>
> Very ugly. This is based on what I wrote when tracking the UDP v6
> checksum bug (4f2e4ad56a65f3b7d64c258e373cb71e8d2499f4 net: mangle zero
> checksum in skb_checksum_help()), because netperf sends the same message
> over and over...
Thanks a lot, hope you don't mind; I added the code to my github repo:
https://github.com/netoptimizer/network-testing/blob/master/src/udp_snd.c
So I identified the difference, and reason behind the route lookups.
Your program is using send() and I was using sendmsg(). Given
udp_flood is designed to test different calls, I simply added --send as
a new possibility.
https://github.com/netoptimizer/network-testing/commit/16166c2cd1fa8
If I use --write instead, then I can also avoid the fib_table_lookup
and __ip_route_output_key_hash calls.
> Use -d 2 to remove the ip_idents_reserve() overhead.
#define IP_PMTUDISC_DO 2 /* Always DF */
Added a --pmtu option to my udp_flood program
https://github.com/netoptimizer/network-testing/commit/23a78caf4bb5b
> #define _GNU_SOURCE
>
> #include <errno.h>
> #include <error.h>
> #include <linux/errqueue.h>
> #include <netinet/in.h>
> #include <sched.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/time.h>
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <unistd.h>
>
> char buffer[1400];
>
> int main(int argc, char** argv) {
> int fd, i;
> struct sockaddr_in6 addr;
> char *host = "2002:af6:798::1";
> int family = AF_INET6;
> int discover = -1;
>
> while ((i = getopt(argc, argv, "4H:d:")) != -1) {
> switch (i) {
> case 'H': host = optarg; break;
> case '4': family = AF_INET; break;
> case 'd': discover = atoi(optarg); break;
> }
> }
> fd = socket(family, SOCK_DGRAM, 0);
> if (fd < 0)
> error(1, errno, "failed to create socket");
> if (discover != -1)
> setsockopt(fd, SOL_IP, IP_MTU_DISCOVER,
> &discover, sizeof(discover));
>
> memset(&addr, 0, sizeof(addr));
> if (family == AF_INET6) {
> addr.sin6_family = AF_INET6;
> addr.sin6_port = htons(9);
> inet_pton(family, host, (void *)&addr.sin6_addr.s6_addr);
> } else {
> struct sockaddr_in *in = (struct sockaddr_in *)&addr;
> in->sin_family = family;
> in->sin_port = htons(9);
> inet_pton(family, host, &in->sin_addr);
> }
> connect(fd, (struct sockaddr *)&addr,
> (family == AF_INET6) ? sizeof(addr) :
> sizeof(struct sockaddr_in));
> memset(buffer, 1, 1400);
> for (i = 0; i < 655360000; i++) {
> memcpy(buffer, &i, sizeof(i));
> send(fd, buffer, 100 + rand() % 200, 0);
Using send() avoids the fib_table_lookup, on a connected UDP socket.
> }
> return 0;
> }
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
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