On Wed, 3 Jun 2020, Giovanni Cabiddu wrote: > > > > +bool adf_should_back_off(struct adf_etr_ring_data *ring) > > > > +{ > > > > + return atomic_read(ring->inflights) > ADF_MAX_INFLIGHTS(ring->ring_size, ring->msg_size) * 15 / 16; > > > How did you came up with 15/16? > > > > I want the sender to back off before the queue is full, to avoid > > busy-waiting. There may be more concurrent senders, so we want to back off > > at some point before the queue is full. > Yes, I understood this. My question was about the actual number. > 93% of the depth of the queue. I just guessed the value. If you have some benchmark, you can try different values, to test if they perform better. Mikulas