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MEDIUM: tasks: check the global task mask instead of the thread number

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When deciding whether to scan the global run queue or not, we currently
check the configured threads number, and if it's 1 we skip the queue
since it's not supposed to be used. However when running with a master
process and multiple threads in the workers, the master will turn this
number back to 1 while some task wakeups might possibly have set bits
in the global tasks mask, thus causing active_tasks_mask to have one
bit permanently set, preventing the process from sleeping.

Instead of checking global.nbthread, let's check for the current
thread's bit in global_tasks_mask. First it will make this part of the
code more consistent, working like a test and set operation, it will
solve the issue with master+nbthread and as a bonus it will save a
lock/unlock for each scheduler call when the thread doesn't have a
task in the global run queue.
This commit is contained in:
Willy Tarreau 2018-12-14 15:49:45 +01:00
parent a1214a501f
commit 1ee55fddea
1 changed files with 1 additions and 1 deletions
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2
src/task.c
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@ -322,7 +322,7 @@ void process_runnable_tasks()
nb_tasks_cur = nb_tasks; nb_tasks_cur = nb_tasks;
max_processed = global.tune.runqueue_depth; max_processed = global.tune.runqueue_depth;
if (likely(global.nbthread > 1)) { if (likely(global_tasks_mask & tid_bit)) {
HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock); HA_SPIN_LOCK(TASK_RQ_LOCK, &rq_lock);
if (!(active_tasks_mask & tid_bit)) { if (!(active_tasks_mask & tid_bit)) {
HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock); HA_SPIN_UNLOCK(TASK_RQ_LOCK, &rq_lock);