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Message-ID: <20081224223142.12176.9916.stgit@lost.foo-projects.org>
Date: Wed, 24 Dec 2008 14:31:42 -0800
From: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, jeff@...zik.org,
Alexander Duyck <alexander.h.duyck@...el.com>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [NET-NEXT PATCH 1/2] igb: defeature tx head writeback
From: Alexander Duyck <alexander.h.duyck@...el.com>
This patch removes tx head writeback as it was found to not provide a
significant improvement in tx performance and on some systems has been seen
to cause a performance degredation due to partial cache line writes.
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
drivers/net/igb/e1000_defines.h | 1
drivers/net/igb/igb.h | 5 +-
drivers/net/igb/igb_main.c | 85 +++++++++++++++++----------------------
3 files changed, 39 insertions(+), 52 deletions(-)
diff --git a/drivers/net/igb/e1000_defines.h b/drivers/net/igb/e1000_defines.h
index c5fe784..40d0342 100644
--- a/drivers/net/igb/e1000_defines.h
+++ b/drivers/net/igb/e1000_defines.h
@@ -323,6 +323,7 @@
#define E1000_TXD_CMD_IFCS 0x02000000 /* Insert FCS (Ethernet CRC) */
#define E1000_TXD_CMD_RS 0x08000000 /* Report Status */
#define E1000_TXD_CMD_DEXT 0x20000000 /* Descriptor extension (0 = legacy) */
+#define E1000_TXD_STAT_DD 0x00000001 /* Descriptor Done */
/* Extended desc bits for Linksec and timesync */
/* Transmit Control */
diff --git a/drivers/net/igb/igb.h b/drivers/net/igb/igb.h
index 2121b8b..c906325 100644
--- a/drivers/net/igb/igb.h
+++ b/drivers/net/igb/igb.h
@@ -43,8 +43,6 @@ struct igb_adapter;
#endif
/* Interrupt defines */
-#define IGB_MAX_TX_CLEAN 72
-
#define IGB_MIN_DYN_ITR 3000
#define IGB_MAX_DYN_ITR 96000
@@ -127,7 +125,8 @@ struct igb_buffer {
/* TX */
struct {
unsigned long time_stamp;
- u32 length;
+ u16 length;
+ u16 next_to_watch;
};
/* RX */
struct {
diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 6a40d94..4962cdf 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -1575,8 +1575,7 @@ int igb_setup_tx_resources(struct igb_adapter *adapter,
memset(tx_ring->buffer_info, 0, size);
/* round up to nearest 4K */
- tx_ring->size = tx_ring->count * sizeof(struct e1000_tx_desc)
- + sizeof(u32);
+ tx_ring->size = tx_ring->count * sizeof(struct e1000_tx_desc);
tx_ring->size = ALIGN(tx_ring->size, 4096);
tx_ring->desc = pci_alloc_consistent(pdev, tx_ring->size,
@@ -1635,7 +1634,7 @@ static int igb_setup_all_tx_resources(struct igb_adapter *adapter)
**/
static void igb_configure_tx(struct igb_adapter *adapter)
{
- u64 tdba, tdwba;
+ u64 tdba;
struct e1000_hw *hw = &adapter->hw;
u32 tctl;
u32 txdctl, txctrl;
@@ -1651,12 +1650,6 @@ static void igb_configure_tx(struct igb_adapter *adapter)
tdba & 0x00000000ffffffffULL);
wr32(E1000_TDBAH(i), tdba >> 32);
- tdwba = ring->dma + ring->count * sizeof(struct e1000_tx_desc);
- tdwba |= 1; /* enable head wb */
- wr32(E1000_TDWBAL(i),
- tdwba & 0x00000000ffffffffULL);
- wr32(E1000_TDWBAH(i), tdwba >> 32);
-
ring->head = E1000_TDH(i);
ring->tail = E1000_TDT(i);
writel(0, hw->hw_addr + ring->tail);
@@ -2710,6 +2703,7 @@ static inline int igb_tso_adv(struct igb_adapter *adapter,
context_desc->seqnum_seed = 0;
buffer_info->time_stamp = jiffies;
+ buffer_info->next_to_watch = i;
buffer_info->dma = 0;
i++;
if (i == tx_ring->count)
@@ -2773,6 +2767,7 @@ static inline bool igb_tx_csum_adv(struct igb_adapter *adapter,
cpu_to_le32(tx_ring->queue_index << 4);
buffer_info->time_stamp = jiffies;
+ buffer_info->next_to_watch = i;
buffer_info->dma = 0;
i++;
@@ -2791,8 +2786,8 @@ static inline bool igb_tx_csum_adv(struct igb_adapter *adapter,
#define IGB_MAX_DATA_PER_TXD (1<<IGB_MAX_TXD_PWR)
static inline int igb_tx_map_adv(struct igb_adapter *adapter,
- struct igb_ring *tx_ring,
- struct sk_buff *skb)
+ struct igb_ring *tx_ring, struct sk_buff *skb,
+ unsigned int first)
{
struct igb_buffer *buffer_info;
unsigned int len = skb_headlen(skb);
@@ -2806,6 +2801,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
buffer_info->length = len;
/* set time_stamp *before* dma to help avoid a possible race */
buffer_info->time_stamp = jiffies;
+ buffer_info->next_to_watch = i;
buffer_info->dma = pci_map_single(adapter->pdev, skb->data, len,
PCI_DMA_TODEVICE);
count++;
@@ -2823,6 +2819,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
BUG_ON(len >= IGB_MAX_DATA_PER_TXD);
buffer_info->length = len;
buffer_info->time_stamp = jiffies;
+ buffer_info->next_to_watch = i;
buffer_info->dma = pci_map_page(adapter->pdev,
frag->page,
frag->page_offset,
@@ -2835,8 +2832,9 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
i = 0;
}
- i = (i == 0) ? tx_ring->count - 1 : i - 1;
+ i = ((i == 0) ? tx_ring->count - 1 : i - 1);
tx_ring->buffer_info[i].skb = skb;
+ tx_ring->buffer_info[first].next_to_watch = i;
return count;
}
@@ -2943,6 +2941,7 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
struct igb_ring *tx_ring)
{
struct igb_adapter *adapter = netdev_priv(netdev);
+ unsigned int first;
unsigned int tx_flags = 0;
unsigned int len;
u8 hdr_len = 0;
@@ -2979,6 +2978,8 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
if (skb->protocol == htons(ETH_P_IP))
tx_flags |= IGB_TX_FLAGS_IPV4;
+ first = tx_ring->next_to_use;
+
tso = skb_is_gso(skb) ? igb_tso_adv(adapter, tx_ring, skb, tx_flags,
&hdr_len) : 0;
@@ -2994,7 +2995,7 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
tx_flags |= IGB_TX_FLAGS_CSUM;
igb_tx_queue_adv(adapter, tx_ring, tx_flags,
- igb_tx_map_adv(adapter, tx_ring, skb),
+ igb_tx_map_adv(adapter, tx_ring, skb, first),
skb->len, hdr_len);
netdev->trans_start = jiffies;
@@ -3617,12 +3618,6 @@ static int igb_clean_rx_ring_msix(struct napi_struct *napi, int budget)
return 1;
}
-static inline u32 get_head(struct igb_ring *tx_ring)
-{
- void *end = (struct e1000_tx_desc *)tx_ring->desc + tx_ring->count;
- return le32_to_cpu(*(volatile __le32 *)end);
-}
-
/**
* igb_clean_tx_irq - Reclaim resources after transmit completes
* @adapter: board private structure
@@ -3631,24 +3626,25 @@ static inline u32 get_head(struct igb_ring *tx_ring)
static bool igb_clean_tx_irq(struct igb_ring *tx_ring)
{
struct igb_adapter *adapter = tx_ring->adapter;
- struct e1000_hw *hw = &adapter->hw;
struct net_device *netdev = adapter->netdev;
- struct e1000_tx_desc *tx_desc;
+ struct e1000_hw *hw = &adapter->hw;
struct igb_buffer *buffer_info;
struct sk_buff *skb;
- unsigned int i;
- u32 head, oldhead;
- unsigned int count = 0;
+ union e1000_adv_tx_desc *tx_desc, *eop_desc;
unsigned int total_bytes = 0, total_packets = 0;
- bool retval = true;
+ unsigned int i, eop, count = 0;
+ bool cleaned = false;
- rmb();
- head = get_head(tx_ring);
i = tx_ring->next_to_clean;
- while (1) {
- while (i != head) {
- tx_desc = E1000_TX_DESC(*tx_ring, i);
+ eop = tx_ring->buffer_info[i].next_to_watch;
+ eop_desc = E1000_TX_DESC_ADV(*tx_ring, eop);
+
+ while ((eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD)) &&
+ (count < tx_ring->count)) {
+ for (cleaned = false; !cleaned; count++) {
+ tx_desc = E1000_TX_DESC_ADV(*tx_ring, i);
buffer_info = &tx_ring->buffer_info[i];
+ cleaned = (i == eop);
skb = buffer_info->skb;
if (skb) {
@@ -3663,25 +3659,17 @@ static bool igb_clean_tx_irq(struct igb_ring *tx_ring)
}
igb_unmap_and_free_tx_resource(adapter, buffer_info);
+ tx_desc->wb.status = 0;
i++;
if (i == tx_ring->count)
i = 0;
-
- count++;
- if (count == IGB_MAX_TX_CLEAN) {
- retval = false;
- goto done_cleaning;
- }
}
- oldhead = head;
- rmb();
- head = get_head(tx_ring);
- if (head == oldhead)
- goto done_cleaning;
- } /* while (1) */
-
-done_cleaning:
+
+ eop = tx_ring->buffer_info[i].next_to_watch;
+ eop_desc = E1000_TX_DESC_ADV(*tx_ring, eop);
+ }
+
tx_ring->next_to_clean = i;
if (unlikely(count &&
@@ -3708,7 +3696,6 @@ done_cleaning:
&& !(rd32(E1000_STATUS) &
E1000_STATUS_TXOFF)) {
- tx_desc = E1000_TX_DESC(*tx_ring, i);
/* detected Tx unit hang */
dev_err(&adapter->pdev->dev,
"Detected Tx Unit Hang\n"
@@ -3717,9 +3704,9 @@ done_cleaning:
" TDT <%x>\n"
" next_to_use <%x>\n"
" next_to_clean <%x>\n"
- " head (WB) <%x>\n"
"buffer_info[next_to_clean]\n"
" time_stamp <%lx>\n"
+ " next_to_watch <%x>\n"
" jiffies <%lx>\n"
" desc.status <%x>\n",
tx_ring->queue_index,
@@ -3727,10 +3714,10 @@ done_cleaning:
readl(adapter->hw.hw_addr + tx_ring->tail),
tx_ring->next_to_use,
tx_ring->next_to_clean,
- head,
tx_ring->buffer_info[i].time_stamp,
+ eop,
jiffies,
- tx_desc->upper.fields.status);
+ eop_desc->wb.status);
netif_stop_subqueue(netdev, tx_ring->queue_index);
}
}
@@ -3740,7 +3727,7 @@ done_cleaning:
tx_ring->tx_stats.packets += total_packets;
adapter->net_stats.tx_bytes += total_bytes;
adapter->net_stats.tx_packets += total_packets;
- return retval;
+ return (count < tx_ring->count);
}
#ifdef CONFIG_IGB_LRO
--
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