Hello,
On Wed, Oct 19, 2022 at 6:51 PM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
>
> From: Uladzislau Rezki <urezki@xxxxxxxxx>
>
> call_rcu() changes to save power will slow down RCU workqueue items
> queued via queue_rcu_work(). This may not be an issue, however we cannot
> assume that workqueue users are OK with long delays. Use
> call_rcu_flush() API instead which reverts to the old behavio
On ChromeOS, I can see that queue_rcu_work() is pretty noisy and the
batching is much better if we can just keep it as call_rcu() instead
of call_rcu_flush().
Is there really any reason to keep it as call_rcu_flush() ? If I
recall, the real reason Vlad's system was slowing down was because of
scsi and the queue_rcu_work() conversion was really a red herring.
Vlad, any thoughts?
thanks,
- Joel
.
>
> Signed-off-by: Uladzislau Rezki <urezki@xxxxxxxxx>
> Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> ---
> kernel/workqueue.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 7cd5f5e7e0a1b..b4b0e828b529e 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1771,7 +1771,7 @@ bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork)
>
> if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
> rwork->wq = wq;
> - call_rcu(&rwork->rcu, rcu_work_rcufn);
> + call_rcu_flush(&rwork->rcu, rcu_work_rcufn);
> return true;
> }
>
> --
> 2.31.1.189.g2e36527f23
>
