ixgbevf: Cleanup variable usage, improve stack performance

This change is meant to help cleanup the usage of temporary variables
within the Rx hot-path by removing unnecessary variables and reducing
the scope of variables that do not need to exist outside the main loop.

CC: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index 36b005e..f864da9 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -517,26 +517,28 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector,
                                struct ixgbevf_ring *rx_ring,
                                int budget)
 {
-       union ixgbe_adv_rx_desc *rx_desc, *next_rxd;
-       struct ixgbevf_rx_buffer *rx_buffer_info, *next_buffer;
-       struct sk_buff *skb;
+       union ixgbe_adv_rx_desc *rx_desc;
        unsigned int i;
        unsigned int total_rx_bytes = 0, total_rx_packets = 0;
        u16 cleaned_count = ixgbevf_desc_unused(rx_ring);
 
        i = rx_ring->next_to_clean;
        rx_desc = IXGBEVF_RX_DESC(rx_ring, i);
-       rx_buffer_info = &rx_ring->rx_buffer_info[i];
 
        while (ixgbevf_test_staterr(rx_desc, IXGBE_RXD_STAT_DD)) {
+               union ixgbe_adv_rx_desc *next_rxd;
+               struct ixgbevf_rx_buffer *rx_buffer_info;
+               struct sk_buff *skb;
+
                if (!budget)
                        break;
                budget--;
 
                rmb(); /* read descriptor and rx_buffer_info after status DD */
 
+               rx_buffer_info = &rx_ring->rx_buffer_info[i];
                skb = rx_buffer_info->skb;
-               prefetch(skb->data - NET_IP_ALIGN);
+               prefetch(skb->data);
                rx_buffer_info->skb = NULL;
 
                dma_unmap_single(rx_ring->dev, rx_buffer_info->dma,
@@ -545,18 +547,17 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector,
                rx_buffer_info->dma = 0;
                skb_put(skb, le16_to_cpu(rx_desc->wb.upper.length));
 
+               cleaned_count++;
+
                i++;
                if (i == rx_ring->count)
                        i = 0;
 
                next_rxd = IXGBEVF_RX_DESC(rx_ring, i);
                prefetch(next_rxd);
-               cleaned_count++;
-
-               next_buffer = &rx_ring->rx_buffer_info[i];
 
                if (!(ixgbevf_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP))) {
-                       skb->next = next_buffer->skb;
+                       skb->next = rx_ring->rx_buffer_info[i].skb;
                        IXGBE_CB(skb->next)->prev = skb;
                        rx_ring->rx_stats.non_eop_descs++;
                        goto next_desc;
@@ -609,6 +610,7 @@ next_desc:
                /* use prefetched values */
                rx_desc = next_rxd;
                rx_buffer_info = &rx_ring->rx_buffer_info[i];
+               rx_desc = IXGBEVF_RX_DESC(rx_ring, i);
        }
 
        rx_ring->next_to_clean = i;