rcu: Reduce synchronize_rcu() delays when all wait heads are in use
When all wait heads are in use, which can happen when
rcu_sr_normal_gp_cleanup_work()'s callback processing
is slow, any new synchronize_rcu() user's rcu_synchronize
node's processing is deferred to future GP periods. This
can result in long list of synchronize_rcu() invocations
waiting for full grace period processing, which can delay
freeing of memory. Mitigate this problem by using first
node in the list as wait tail when all wait heads are in use.
While methods to speed up callback processing would be needed
to recover from this situation, allowing new nodes to complete
their grace period can help prevent delays due to a fixed
number of wait head nodes.
Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
1 file changed
