Calling setsockopt many times - sockets

Question

I have application which uses sockets to transfer data between two clients. It uses a single socket to communicate control and data traffic (over UDP).
Qos and tos fields of IP header can be changed using
setsockopt(sockfd, IPPROTO_IP, IP_TOS, &tos, toslen);
setsockopt(sockfd, SOL_SOCKET, SO_PRIORITY, &cos, coslen);
But how many calls to setsockopt (to the same socket) is too many?
For example, lets assume it will be called every 1ms.
To narrow question scope, I am asking about modern linux system (generic explanation is more than welcomed).
Here is an example to demonstrate it (this is the sending-only part of the application):
#include <stdlib.h>
#include <memory.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#define NPACK 10000
#define PORT 44444
#define BUFLEN 128
void diep(char *s) {
perror(s);
exit(1);
}
#define SRV_IP "12.34.56.78"
int main(void) {
struct sockaddr_in si_other, si_me;
int s, i, slen = sizeof(si_other);
int toss[2] = { 56, 160 }, coss[] = { 1, 3 };
char buf[BUFLEN];
//Create UDP socket
if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
diep("socket");
//Create remote socket
memset((char *) &si_other, 0, sizeof(si_other));
si_other.sin_family = AF_INET;
si_other.sin_port = htons(PORT);
if (inet_aton(SRV_IP, &si_other.sin_addr) == 0) {
fprintf(stderr, "inet_aton() failed\n");
exit(1);
}
//Create local socket and bind to it.
memset((char *) &si_me, 0, sizeof(si_me));
si_me.sin_family = AF_INET;
si_me.sin_port = htons(PORT);
si_me.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(s, &si_me, sizeof(si_me)) == -1)
diep("bind");
//Loop on number of packets
for (i = 0; i < NPACK; i++) {
sprintf(buf, "This is packet %d, %d\n", i, toss[i % 2]);
printf("Sending packet %d. %s", i, buf);
//Change tos and cos. odd packets high priority , even packets low priority.
setsockopt(s, IPPROTO_IP, IP_TOS, &toss[i % 2], sizeof(int));
setsockopt(s, SOL_SOCKET, SO_PRIORITY, &coss[i % 2], sizeof(int));
//Send!
if (sendto(s, buf, strlen(buf), 0, &si_other, slen) == -1)
diep("sendto()");
}
close(s);
return 0;
}
NOTES:
Both control and data should share the same socket (same UDP source port).
Multiple threads will use the same socket (so some locking mechanism needed between setsockopt and sendto; but this is outside the scope of the question).
SO_PRIORITY is linux only.