| Message ID | 20221016162305.2489629-7-joel@joelfernandes.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 43a36e3121ef44f90970e9c6d138b7072e2fbf2c |
| Headers | show |
| Series | rcu: call_rcu() power improvements | expand |
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index e5c5315da274..65c58a029297 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -230,7 +230,8 @@ static void __percpu_ref_switch_to_atomic(struct percpu_ref *ref, percpu_ref_noop_confirm_switch; percpu_ref_get(ref); /* put after confirmation */ - call_rcu(&ref->data->rcu, percpu_ref_switch_to_atomic_rcu); + call_rcu_flush(&ref->data->rcu, + percpu_ref_switch_to_atomic_rcu); } static void __percpu_ref_switch_to_percpu(struct percpu_ref *ref)
call_rcu() changes to save power will slow down the percpu refcounter's "per-CPU to atomic switch" path. The primitive uses RCU when switching to atomic mode. The enqueued async callback wakes up waiters waiting in the percpu_ref_switch_waitq. Due to this, per-CPU refcount users will slow down, such as blk_pre_runtime_suspend(). Use the call_rcu_flush() API instead which reverts to the old behavior. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> --- lib/percpu-refcount.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)