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ixgbe: Update method used for determining descriptor count for an skb 

This patch updates the current methods used for determining if we have
enough space to transmit a given skb.  The current method is quite wasteful
as it has us go through and determine how each page is going to be broken
up.  That only needs to be done if pages are larger than our maximum data
per TXD.  As such I have wrapped that in a page size check.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Alexander Duyck 2011-05-27 05:31:52 +00:00 committed by Jeff Kirsher
parent 897ab15606
commit a535c30e9e
2 changed files with 33 additions and 29 deletions
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7
drivers/net/ixgbe/ixgbe.h
View File

@ -131,6 +131,13 @@ struct vf_macvlans {
u8 vf_macvlan[ETH_ALEN];
};
#define IXGBE_MAX_TXD_PWR 14
#define IXGBE_MAX_DATA_PER_TXD (1 << IXGBE_MAX_TXD_PWR)
/* Tx Descriptors needed, worst case */
#define TXD_USE_COUNT(S) DIV_ROUND_UP((S), IXGBE_MAX_DATA_PER_TXD)
#define DESC_NEEDED ((MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE)) + 4)
/* wrapper around a pointer to a socket buffer,
* so a DMA handle can be stored along with the buffer */
struct ixgbe_tx_buffer {

55
drivers/net/ixgbe/ixgbe_main.c
View File

@ -772,15 +772,6 @@ static inline bool ixgbe_check_tx_hang(struct ixgbe_ring *tx_ring)
return ret;
}
#define IXGBE_MAX_TXD_PWR 14
#define IXGBE_MAX_DATA_PER_TXD (1 << IXGBE_MAX_TXD_PWR)
/* Tx Descriptors needed, worst case */
#define TXD_USE_COUNT(S) (((S) >> IXGBE_MAX_TXD_PWR) + \
(((S) & (IXGBE_MAX_DATA_PER_TXD - 1)) ? 1 : 0))
#define DESC_NEEDED (TXD_USE_COUNT(IXGBE_MAX_DATA_PER_TXD) /* skb->data */ + \
MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE) + 1) /* for context */
/**
* ixgbe_tx_timeout_reset - initiate reset due to Tx timeout
* @adapter: driver private struct
@ -6832,14 +6823,34 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
struct ixgbe_adapter *adapter,
struct ixgbe_ring *tx_ring)
{
unsigned int tx_flags = 0;
int tso;
u16 count = 0;
u32 tx_flags = 0;
#if PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
unsigned short f;
#endif
u16 first;
unsigned int f;
u16 count = TXD_USE_COUNT(skb_headlen(skb));
__be16 protocol;
u8 hdr_len = 0;
/*
* need: 1 descriptor per page * PAGE_SIZE/IXGBE_MAX_DATA_PER_TXD,
* + 1 desc for skb_head_len/IXGBE_MAX_DATA_PER_TXD,
* + 2 desc gap to keep tail from touching head,
* + 1 desc for context descriptor,
* otherwise try next time
*/
#if PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
count += TXD_USE_COUNT(skb_shinfo(skb)->frags[f].size);
#else
count += skb_shinfo(skb)->nr_frags;
#endif
if (ixgbe_maybe_stop_tx(tx_ring, count + 3)) {
tx_ring->tx_stats.tx_busy++;
return NETDEV_TX_BUSY;
}
protocol = vlan_get_protocol(skb);
if (vlan_tx_tag_present(skb)) {
@ -6863,25 +6874,11 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
if (adapter->flags & IXGBE_FLAG_FCOE_ENABLED &&
(protocol == htons(ETH_P_FCOE)))
tx_flags |= IXGBE_TX_FLAGS_FCOE;
#endif
/* four things can cause us to need a context descriptor */
if (skb_is_gso(skb) ||
(skb->ip_summed == CHECKSUM_PARTIAL) ||
(tx_flags & IXGBE_TX_FLAGS_VLAN) ||
(tx_flags & IXGBE_TX_FLAGS_FCOE))
count++;
count += TXD_USE_COUNT(skb_headlen(skb));
for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
count += TXD_USE_COUNT(skb_shinfo(skb)->frags[f].size);
if (ixgbe_maybe_stop_tx(tx_ring, count)) {
tx_ring->tx_stats.tx_busy++;
return NETDEV_TX_BUSY;
}
/* record the location of the first descriptor for this packet */
first = tx_ring->next_to_use;
if (tx_flags & IXGBE_TX_FLAGS_FCOE) {
#ifdef IXGBE_FCOE
/* setup tx offload for FCoE */