sky2: rx allocation threshold change

When using larger MTU's sky2 driver changes from allocating one
data area, to using multiple pages. The threshold for this was based on
a heuristic where the cost of a single allocation is bigger than one
page.  Since the allocator has changed, this heuristic is now incorrect;
instead just make the threshold be when the total size of the allocation
is greater than one page.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 9 insertions, 19 deletions

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 30e567a2d5a1..c177e87182f4 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -1234,7 +1234,7 @@ static int sky2_rx_start(struct sky2_port *sky2)
         struct sky2_hw *hw = sky2->hw;
         struct rx_ring_info *re;
         unsigned rxq = rxqaddr[sky2->port];
-        unsigned i, size, space, thresh;
+        unsigned i, size, thresh;
 
         sky2->rx_put = sky2->rx_next = 0;
         sky2_qset(hw, rxq);
@@ -1261,28 +1261,18 @@ static int sky2_rx_start(struct sky2_port *sky2)
         /* Stopping point for hardware truncation */
         thresh = (size - 8) / sizeof(u32);
 
-        /* Account for overhead of skb - to avoid order > 0 allocation */
-        space = SKB_DATA_ALIGN(size) + NET_SKB_PAD
-                + sizeof(struct skb_shared_info);
-
-        sky2->rx_nfrags = space >> PAGE_SHIFT;
+        sky2->rx_nfrags = size >> PAGE_SHIFT;
         BUG_ON(sky2->rx_nfrags > ARRAY_SIZE(re->frag_addr));
 
-        if (sky2->rx_nfrags != 0) {
-                /* Compute residue after pages */
-                space = sky2->rx_nfrags << PAGE_SHIFT;
+        /* Compute residue after pages */
+        size -= sky2->rx_nfrags << PAGE_SHIFT;
 
-                if (space < size)
-                        size -= space;
-                else
-                        size = 0;
+        /* Optimize to handle small packets and headers */
+        if (size < copybreak)
+                size = copybreak;
+        if (size < ETH_HLEN)
+                size = ETH_HLEN;
 
-                /* Optimize to handle small packets and headers */
-                if (size < copybreak)
-                        size = copybreak;
-                if (size < ETH_HLEN)
-                        size = ETH_HLEN;
-        }
         sky2->rx_data_size = size;
 
         /* Fill Rx ring */