[PATCH 2/2] sky2: rx allocation threshold change
From: Stephen Hemminger <hidden>
Date: 2007-11-28 23:35:59
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 <redacted>
--- a/drivers/net/sky2.c 2007-11-28 08:46:57.000000000 -0800
+++ b/drivers/net/sky2.c 2007-11-28 14:48:26.000000000 -0800@@ -1231,7 +1231,7 @@ static int sky2_rx_start(struct sky2_por 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);
@@ -1258,28 +1258,18 @@ static int sky2_rx_start(struct sky2_por /* 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 */