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sd-event: make use of epoll_pwait2() for greater time accuracy

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This commit is contained in:
Lennart Poettering
2021-02-26 09:22:09 +01:00
parent 420297c9e1
commit 798445ab84
1 changed files with 59 additions and 14 deletions
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src/libsystemd/sd-event/sd-event.c
+59 -14
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@@ -3780,9 +3780,59 @@ pending:
return r;
}
static int epoll_wait_usec(
int fd,
struct epoll_event *events,
int maxevents,
usec_t timeout) {
static bool epoll_pwait2_absent = false;
int r, msec;
/* A wrapper that uses epoll_pwait2() if available, and falls back to epoll_wait() if not */
if (!epoll_pwait2_absent && timeout != USEC_INFINITY) {
struct timespec ts;
r = epoll_pwait2(fd,
events,
maxevents,
timespec_store(&ts, timeout),
NULL);
if (r >= 0)
return r;
if (!ERRNO_IS_NOT_SUPPORTED(r) && !ERRNO_IS_PRIVILEGE(r))
return -errno; /* Only fallback to old epoll_wait() if the syscall is masked or not
* supported. */
epoll_pwait2_absent = true;
}
if (timeout == USEC_INFINITY)
msec = -1;
else {
usec_t k;
k = DIV_ROUND_UP(timeout, USEC_PER_MSEC);
if (k >= INT_MAX)
msec = INT_MAX; /* Saturate */
else
msec = (int) k;
}
r = epoll_wait(fd,
events,
maxevents,
msec);
if (r < 0)
return -errno;
return r;
}
_public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
size_t n_event_queue, m;
int r, msec;
int r;
assert_return(e, -EINVAL);
assert_return(e = event_resolve(e), -ENOPKG);
@@ -3801,21 +3851,16 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
/* If we still have inotify data buffered, then query the other fds, but don't wait on it */
if (e->inotify_data_buffered)
msec = 0;
else
msec = timeout == (uint64_t) -1 ? -1 : (int) DIV_ROUND_UP(timeout, USEC_PER_MSEC);
timeout = 0;
for (;;) {
r = epoll_wait(e->epoll_fd, e->event_queue, e->event_queue_allocated, msec);
if (r < 0) {
if (errno == EINTR) {
e->state = SD_EVENT_PENDING;
return 1;
}
r = -errno;
goto finish;
r = epoll_wait_usec(e->epoll_fd, e->event_queue, e->event_queue_allocated, timeout);
if (r == -EINTR) {
e->state = SD_EVENT_PENDING;
return 1;
}
if (r < 0)
goto finish;
m = (size_t) r;
@@ -3828,7 +3873,7 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
if (!GREEDY_REALLOC(e->event_queue, e->event_queue_allocated, e->event_queue_allocated + n_event_queue))
return -ENOMEM;
msec = 0;
timeout = 0;
}
triple_timestamp_get(&e->timestamp);