[openib-general] Re: LLTX and netif_stop_queue

[Francois Romieu]

David S. Miller <davem at davemloft.net> :
[...]
> Originally, dev->xmit_lock was added so that drivers that were SMP dumb
> could stay that way.  Thus preserving the guarentee that there would be
> only one active call into the dev->hard_start_xmit method across the
> entire system.  I don't think any of that is relevant any longer.  All
> of our network drivers are pretty clean in this regard.

(nit)

Almost all. I used the fact that dev->hard_start_xmit was issued in
a bh disabled context to exchange spinlock_irqsave for ordered ops
on ring indexes so as to sync hard_start_xmit and the irq handler in
the r8169 driver. It is a bit sick but Jon Mason reported it made a
noticeable difference to avoid the irqsave on its 4 way ppc64 and 
nobody complained about it.

--
Ueimor