netdev - [net-next PATCH V2 3/3] ixgbe: bulk free SKBs during TX completion cleanup cycle

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Message-ID: <20160208121509.8860.83105.stgit@localhost>
Date:	Mon, 08 Feb 2016 13:15:09 +0100
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	netdev@...r.kernel.org, Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, tom@...bertland.com,
	Alexander Duyck <alexander.duyck@...il.com>,
	alexei.starovoitov@...il.com, linux-mm@...ck.org,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	Christoph Lameter <cl@...ux.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [net-next PATCH V2 3/3] ixgbe: bulk free SKBs during TX completion
 cleanup cycle

There is an opportunity to bulk free SKBs during reclaiming of
resources after DMA transmit completes in ixgbe_clean_tx_irq.  Thus,
bulk freeing at this point does not introduce any added latency.

Simply use napi_consume_skb() which were recently introduced.  The
napi_budget parameter is needed by napi_consume_skb() to detect if it
is called from netpoll.

Benchmarking IPv4-forwarding, on CPU i7-4790K @4.2GHz (no turbo boost)
 Single CPU/flow numbers: before: 1982144 pps ->  after : 2064446 pps
 Improvement: +82302 pps, -20 nanosec, +4.1%
 (SLUB and GCC version 5.1.1 20150618 (Red Hat 5.1.1-4))

Joint work with Alexander Duyck.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index c4003a88bbf6..0c701b8438b6 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1089,7 +1089,7 @@ static void ixgbe_tx_timeout_reset(struct ixgbe_adapter *adapter)
  * @tx_ring: tx ring to clean
  **/
 static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
-			       struct ixgbe_ring *tx_ring)
+			       struct ixgbe_ring *tx_ring, int napi_budget)
 {
 	struct ixgbe_adapter *adapter = q_vector->adapter;
 	struct ixgbe_tx_buffer *tx_buffer;
@@ -1127,7 +1127,7 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 		total_packets += tx_buffer->gso_segs;
 
 		/* free the skb */
-		dev_consume_skb_any(tx_buffer->skb);
+		napi_consume_skb(tx_buffer->skb, napi_budget);
 
 		/* unmap skb header data */
 		dma_unmap_single(tx_ring->dev,
@@ -2784,7 +2784,7 @@ int ixgbe_poll(struct napi_struct *napi, int budget)
 #endif
 
 	ixgbe_for_each_ring(ring, q_vector->tx)
-		clean_complete &= !!ixgbe_clean_tx_irq(q_vector, ring);
+		clean_complete &= !!ixgbe_clean_tx_irq(q_vector, ring, budget);
 
 	/* Exit if we are called by netpoll or busy polling is active */
 	if ((budget <= 0) || !ixgbe_qv_lock_napi(q_vector))