sfc: Add option to use a separate channel for TX completions

In a bidirectional forwarding test, we find that the best performance
is achieved by sending the TX completion interrupts from one NIC to a
CPU which shares an L2 cache with RX completion interrupts from the
other NIC.  To facilitate this, add an option (through a module
parameter) to create separate channels for RX and TX completion with
separate IRQs when MSI-X is available.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index f91060963475..2c5b5fabac1e 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -649,6 +649,7 @@ union efx_multicast_hash {
  * @rx_queue: RX DMA queues
  * @channel: Channels
  * @n_rx_queues: Number of RX queues
+ * @n_channels: Number of channels in use
  * @rx_buffer_len: RX buffer length
  * @rx_buffer_order: Order (log2) of number of pages for each RX buffer
  * @irq_status: Interrupt status buffer
@@ -728,6 +729,7 @@ struct efx_nic {
         struct efx_channel channel[EFX_MAX_CHANNELS];
 
         int n_rx_queues;
+        int n_channels;
         unsigned int rx_buffer_len;
         unsigned int rx_buffer_order;