On Wed, 4 Jun 2025 14:46:27 GMT, Johannes Bechberger <jbechber...@openjdk.org>
wrote:
>> Sorry where does it say that? I think you are looking at the example in that
>> page which makes use of sival_ptr in the signal handler. In that example
>> reading from that timer address in the handler is valid but for us we would
>> be accessing invalid memory. Plus we are not really reading it.
>
> Why would we be accessing invalid memory?
Which differences to the example code are you seeing?
sev.sigev_notify = SIGEV_SIGNAL;
sev.sigev_signo = SIG;
sev.sigev_value.sival_ptr = &timerid;
if (timer_create(CLOCKID, &sev, &timerid) == -1)
errExit("timer_create");
printf("timer ID is %#jx\n", (uintmax_t) timerid);
/* Start the timer. */
freq_nanosecs = atoll(argv[2]);
its.it_value.tv_sec = freq_nanosecs / 1000000000;
its.it_value.tv_nsec = freq_nanosecs % 1000000000;
its.it_interval.tv_sec = its.it_value.tv_sec;
its.it_interval.tv_nsec = its.it_value.tv_nsec;
Is similar to:
((int*)&sev.sigev_notify)[1] = thread->osthread()->thread_id();
clockid_t clock;
int err = pthread_getcpuclockid(thread->osthread()->pthread_id(), &clock);
if (err != 0) {
log_error(jfr)("Failed to get clock for thread sampling: %s",
os::strerror(err));
return false;
}
if (timer_create(clock, &sev, &t) < 0) {
return false;
}
int64_t period = get_sampling_period();
if (period != 0) {
set_timer_time(t, period);
}
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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2126810984
