tree 96b76ececc603e511c184d8249e82b60340427de
parent b64c5a252916a4ec3c071832cf2ab873ba64c711
author Paul E. McKenney <paulmck@kernel.org> 1643848480 -0800
committer Paul E. McKenney <paulmck@kernel.org> 1643850188 -0800

rcu-tasks: Set ->percpu_enqueue_shift to zero upon contention

Currently, call_rcu_tasks_generic() sets ->percpu_enqueue_shift to
order_base_2(nr_cpu_ids) upon encountering sufficient contention.
This does not shift to use of non-CPU-0 callback queues as intended, but
rather continues using only CPU 0's queue.  Although this does provide
some decrease in contention due to spreading work over multiple locks,
it is not the dramatic decrease that was intended.

This commit therefore makes call_rcu_tasks_generic() set
->percpu_enqueue_shift to 0.

Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>