[openib-general] Re: [PATCH (updated)] ipoib: dont lock tx on completion

[Roland Dreier]

    Michael> By testing again, and waking the net queue if completions
    Michael> arrived, we can avoid taking the tx lock on send
    Michael> completion in ip over ib, reducing the lock contention.

    Michael> An exception is when the interface is locked: in that
    Michael> case we have to look at the head and tail values, so its
    Michael> easier to take the lock than worry about smp issues.

Hmm, I still need to think about this for a while.  For example, I
can't convince myself easily that nothing bad can happen if we test
netif_queue_stopped() outside of a locked region.

 - R.