drbr_enqueue - OCE driver - Freebsd 9.1

[Duvvuru,Venkat Kumar]

Hi,
In the transmit path, if enqueue mechanism is used instead of blocking on the lock, the throughput is not good in some scenarios (especially single queue, multiple connections).
For example:
if (TRY_LOCK(&wq->tx_lock)) {
           status = oce_multiq_transmit(ifp, m, wq);
           UNLOCK(&wq->tx_lock);
     } else {
           status = drbr_enqueue(ifp, wq->br, m);
     }

Instead of the above code where the request is enqueued if I use a normal LOCK and block on it, it is giving good performance.

Any suggestions on why the throughput is low in case of enqueue mechanism.

Thx,
Venkat.