From: John Allen <jal...@linux.vnet.ibm.com> Date: Tue, 12 Apr 2016 16:00:23 -0500
> On 04/12/2016 03:12 PM, Eric Dumazet wrote: >> On Tue, 2016-04-12 at 14:38 -0500, John Allen wrote: >>> Moves tx completion processing out of interrupt context, deferring work >>> using a wait queue. With this work now deferred, we must account for the >>> possibility that skbs can be sent faster than we can process completion >>> requests in which case the tx buffer will overflow. If the tx buffer is >>> full, ibmvnic_xmit will return NETDEV_TX_BUSY and stop the current tx >>> queue. Subsequently, the queue will be restarted in ibmvnic_complete_tx >>> when all pending tx completion requests have been cleared. >> >> 1) Why is this needed ? > > In the current ibmvnic implementation, tx completion processing is done in > interrupt context. Depending on the load, this can block further > interrupts for a long time. This patch just creates a bottom half so that > when a tx completion interrupt comes in, we can defer the majority of the > work and exit interrupt context quickly. You should use NAPI polling for this, not your own invented mechanism.
