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selftests: Add test for timing a bind request to a port with a popula…
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…ted bhash entry

This test populates the bhash table for a given port with
MAX_THREADS * MAX_CONNECTIONS sockets, and then times how long
a bind request on the port takes.

When populating the bhash table, we create the sockets and then bind
the sockets to the same address and port (SO_REUSEADDR and SO_REUSEPORT
are set). When timing how long a bind on the port takes, we bind on a
different address without SO_REUSEPORT set. We do not set SO_REUSEPORT
because we are interested in the case where the bind request does not
go through the tb->fastreuseport path, which is fragile (eg
tb->fastreuseport path does not work if binding with a different uid).

To run the test locally, I did:
* ulimit -n 65535000
* ip addr add 2001:0db8:0:f101::1 dev eth0
* ./bind_bhash_test 443

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Joanne Koong authored and Jakub Kicinski committed May 21, 2022
1 parent d5a42de commit 538aaf9
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1 change: 1 addition & 0 deletions tools/testing/selftests/net/.gitignore
Original file line number Diff line number Diff line change
Expand Up @@ -36,3 +36,4 @@ gro
ioam6_parser
toeplitz
cmsg_sender
bind_bhash_test
2 changes: 2 additions & 0 deletions tools/testing/selftests/net/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ TEST_GEN_FILES += toeplitz
TEST_GEN_FILES += cmsg_sender
TEST_GEN_FILES += stress_reuseport_listen
TEST_PROGS += test_vxlan_vnifiltering.sh
TEST_GEN_FILES += bind_bhash_test

TEST_FILES := settings

Expand All @@ -69,4 +70,5 @@ include bpf/Makefile

$(OUTPUT)/reuseport_bpf_numa: LDLIBS += -lnuma
$(OUTPUT)/tcp_mmap: LDLIBS += -lpthread
$(OUTPUT)/bind_bhash_test: LDLIBS += -lpthread
$(OUTPUT)/tcp_inq: LDLIBS += -lpthread
119 changes: 119 additions & 0 deletions tools/testing/selftests/net/bind_bhash_test.c
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@@ -0,0 +1,119 @@
// SPDX-License-Identifier: GPL-2.0
/*
* This times how long it takes to bind to a port when the port already
* has multiple sockets in its bhash table.
*
* In the setup(), we populate the port's bhash table with
* MAX_THREADS * MAX_CONNECTIONS number of entries.
*/

#include <unistd.h>
#include <stdio.h>
#include <netdb.h>
#include <pthread.h>

#define MAX_THREADS 600
#define MAX_CONNECTIONS 40

static const char *bind_addr = "::1";
static const char *port;

static int fd_array[MAX_THREADS][MAX_CONNECTIONS];

static int bind_socket(int opt, const char *addr)
{
struct addrinfo *res, hint = {};
int sock_fd, reuse = 1, err;

sock_fd = socket(AF_INET6, SOCK_STREAM, 0);
if (sock_fd < 0) {
perror("socket fd err");
return -1;
}

hint.ai_family = AF_INET6;
hint.ai_socktype = SOCK_STREAM;

err = getaddrinfo(addr, port, &hint, &res);
if (err) {
perror("getaddrinfo failed");
return -1;
}

if (opt) {
err = setsockopt(sock_fd, SOL_SOCKET, opt, &reuse, sizeof(reuse));
if (err) {
perror("setsockopt failed");
return -1;
}
}

err = bind(sock_fd, res->ai_addr, res->ai_addrlen);
if (err) {
perror("failed to bind to port");
return -1;
}

return sock_fd;
}

static void *setup(void *arg)
{
int sock_fd, i;
int *array = (int *)arg;

for (i = 0; i < MAX_CONNECTIONS; i++) {
sock_fd = bind_socket(SO_REUSEADDR | SO_REUSEPORT, bind_addr);
if (sock_fd < 0)
return NULL;
array[i] = sock_fd;
}

return NULL;
}

int main(int argc, const char *argv[])
{
int listener_fd, sock_fd, i, j;
pthread_t tid[MAX_THREADS];
clock_t begin, end;

if (argc != 2) {
printf("Usage: listener <port>\n");
return -1;
}

port = argv[1];

listener_fd = bind_socket(SO_REUSEADDR | SO_REUSEPORT, bind_addr);
if (listen(listener_fd, 100) < 0) {
perror("listen failed");
return -1;
}

/* Set up threads to populate the bhash table entry for the port */
for (i = 0; i < MAX_THREADS; i++)
pthread_create(&tid[i], NULL, setup, fd_array[i]);

for (i = 0; i < MAX_THREADS; i++)
pthread_join(tid[i], NULL);

begin = clock();

/* Bind to the same port on a different address */
sock_fd = bind_socket(0, "2001:0db8:0:f101::1");

end = clock();

printf("time spent = %f\n", (double)(end - begin) / CLOCKS_PER_SEC);

/* clean up */
close(sock_fd);
close(listener_fd);
for (i = 0; i < MAX_THREADS; i++) {
for (j = 0; i < MAX_THREADS; i++)
close(fd_array[i][j]);
}

return 0;
}

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