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MINOR: task: make tasklet wakeup latency measurements more accurate

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First, we don't want to measure wakeup times if the call date had not
been set before profiling was enabled at run time. And second, we may
only collect the value before clearing the TASK_IN_LIST bit, otherwise
another wakeup might happen on another thread and replace the call date
we're about to use, hence artificially lower the wakeup times.
This commit is contained in:
Willy Tarreau 2021-02-25 09:32:58 +01:00
parent b2285de049
commit 2a54ffbf43
1 changed files with 15 additions and 8 deletions
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23
src/task.c
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@ -495,25 +495,32 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
_HA_ATOMIC_SUB(&sched->rq_total, 1);
if (TASK_IS_TASKLET(t)) {
uint64_t before = 0;
LIST_DEL_INIT(&((struct tasklet *)t)->list);
__ha_barrier_store();
state = _HA_ATOMIC_XCHG(&t->state, state);
__ha_barrier_atomic_store();
if (unlikely(task_profiling_mask & tid_bit)) {
uint64_t before;
profile_entry = sched_activity_entry(sched_activity, t->process);
before = now_mono_time();
#ifdef DEBUG_TASK
HA_ATOMIC_ADD(&profile_entry->lat_time, before - ((struct tasklet *)t)->call_date);
if (((struct tasklet *)t)->call_date) {
HA_ATOMIC_ADD(&profile_entry->lat_time, before - ((struct tasklet *)t)->call_date);
((struct tasklet *)t)->call_date = 0;
}
#endif
process(t, ctx, state);
}
state = _HA_ATOMIC_XCHG(&t->state, state);
__ha_barrier_atomic_store();
process(t, ctx, state);
if (unlikely(task_profiling_mask & tid_bit)) {
HA_ATOMIC_ADD(&profile_entry->calls, 1);
HA_ATOMIC_ADD(&profile_entry->cpu_time, now_mono_time() - before);
} else {
process(t, ctx, state);
}
done++;
sched->current = NULL;
__ha_barrier_store();