At 2021-01-05 21:44:32, "Íõ־ǿ" <00107082@163.com> wrote:
Hi guys,I am having lots of dns 5s delay on a arm/aarch64 platform, after tcpdump capturing dns packages, I found that the delay always happened when A/AAAA queries happened to have same dns transaction id.network/res_mkquery.c.../* Make a reasonably unpredictable id */
clock_gettime(CLOCK_REALTIME, &ts);
id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff;
q[0] = id/256;
q[1] = id;
...time/clock_gettime.c...r = __syscall(SYS_clock_gettime, clk, ts);
if (r == -ENOSYS) {
if (clk == CLOCK_REALTIME) {
__syscall(SYS_gettimeofday, ts, 0);
ts->tv_nsec = (int)ts->tv_nsec * 1000;
return 0;
}
r = -EINVAL;
}
return __syscall_ret(r);
....On aarch64, gettimeofday yields current time with low accuracy, the smallest unit is 1e-6, (I think)Could we add some trick to make sure that the parallel A/AAAA queries got different id?ThanksDavid