[netdrvr] sfc: Add TSO support

The SFC4000 controller does not have hardware support for TSO, and the
core GSO code incurs a high cost in allocating and freeing skbs.  This
TSO implementation uses lightweight packet header structures and is
substantially faster.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index c505482c2520..6ffa71163360 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -134,6 +134,8 @@ struct efx_special_buffer {
  *      Set only on the final fragment of a packet; %NULL for all other
  *      fragments.  When this fragment completes, then we can free this
  *      skb.
+ * @tsoh: The associated TSO header structure, or %NULL if this
+ *      buffer is not a TSO header.
  * @dma_addr: DMA address of the fragment.
  * @len: Length of this fragment.
  *      This field is zero when the queue slot is empty.
@@ -144,6 +146,7 @@ struct efx_special_buffer {
  */
 struct efx_tx_buffer {
         const struct sk_buff *skb;
+        struct efx_tso_header *tsoh;
         dma_addr_t dma_addr;
         unsigned short len;
         unsigned char continuation;
@@ -187,6 +190,13 @@ struct efx_tx_buffer {
  *      variable indicates that the queue is full.  This is to
  *      avoid cache-line ping-pong between the xmit path and the
  *      completion path.
+ * @tso_headers_free: A list of TSO headers allocated for this TX queue
+ *      that are not in use, and so available for new TSO sends. The list
+ *      is protected by the TX queue lock.
+ * @tso_bursts: Number of times TSO xmit invoked by kernel
+ * @tso_long_headers: Number of packets with headers too long for standard
+ *      blocks
+ * @tso_packets: Number of packets via the TSO xmit path
  */
 struct efx_tx_queue {
         /* Members which don't change on the fast path */
@@ -206,6 +216,10 @@ struct efx_tx_queue {
         unsigned int insert_count ____cacheline_aligned_in_smp;
         unsigned int write_count;
         unsigned int old_read_count;
+        struct efx_tso_header *tso_headers_free;
+        unsigned int tso_bursts;
+        unsigned int tso_long_headers;
+        unsigned int tso_packets;
 };
 
 /**