diff options
| -rw-r--r-- | src/libsystemd/sd-event/sd-event.c | 36 |
1 files changed, 21 insertions, 15 deletions
diff --git a/src/libsystemd/sd-event/sd-event.c b/src/libsystemd/sd-event/sd-event.c index a4b67431ef..d6a3d1c3f4 100644 --- a/src/libsystemd/sd-event/sd-event.c +++ b/src/libsystemd/sd-event/sd-event.c @@ -733,12 +733,30 @@ _public_ int sd_event_add_io( return 0; } +static void initialize_perturb(sd_event *e) { + sd_id128_t bootid = {}; + + /* When we sleep for longer, we try to realign the wakeup to + the same time wihtin each minute/second/250ms, so that + events all across the system can be coalesced into a single + CPU wakeup. However, let's take some system-specific + randomness for this value, so that in a network of systems + with synced clocks timer events are distributed a + bit. Here, we calculate a perturbation usec offset from the + boot ID. */ + + if (_likely_(e->perturb != (usec_t) -1)) + return; + + if (sd_id128_get_boot(&bootid) >= 0) + e->perturb = (bootid.qwords[0] ^ bootid.qwords[1]) % USEC_PER_MINUTE; +} + static int event_setup_timer_fd( sd_event *e, struct clock_data *d, clockid_t clock) { - sd_id128_t bootid = {}; struct epoll_event ev = {}; int r, fd; @@ -762,20 +780,6 @@ static int event_setup_timer_fd( } d->fd = fd; - - /* When we sleep for longer, we try to realign the wakeup to - the same time wihtin each minute/second/250ms, so that - events all across the system can be coalesced into a single - CPU wakeup. However, let's take some system-specific - randomness for this value, so that in a network of systems - with synced clocks timer events are distributed a - bit. Here, we calculate a perturbation usec offset from the - boot ID. */ - - if (e->perturb == (usec_t) -1) - if (sd_id128_get_boot(&bootid) >= 0) - e->perturb = (bootid.qwords[0] ^ bootid.qwords[1]) % USEC_PER_MINUTE; - return 0; } @@ -1588,6 +1592,8 @@ static usec_t sleep_between(sd_event *e, usec_t a, usec_t b) { if (b <= a + 1) return a; + initialize_perturb(e); + /* Find a good time to wake up again between times a and b. We have two goals here: |