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Date: Wed, 29 Mar 2017 03:12:09 -0700
From: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To: davem@...emloft.net
Cc: Alexander Duyck <alexander.h.duyck@...el.com>,
netdev@...r.kernel.org, nhorman@...hat.com, sassmann@...hat.com,
jogreene@...hat.com, Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 07/13] i40e/i40evf: Use length to determine if descriptor is done
From: Alexander Duyck <alexander.h.duyck@...el.com>
This change makes it so that we use the length of the packet instead of the
DD status bit to determine if a new descriptor is ready to be processed.
The obvious advantage is that it cuts down on reads as we don't really even
need the DD bit if going from a 0 to a non-zero value on size is enough to
inform us that the packet has been completed.
Change-ID: Iebdf9cdb36c454ef092df27199b92ad09c374231
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 24 ++++++++++++------------
drivers/net/ethernet/intel/i40evf/i40e_txrx.c | 24 ++++++++++++------------
2 files changed, 24 insertions(+), 24 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 2ca8d13baea5..012e55354043 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -1757,6 +1757,7 @@ static bool i40e_add_rx_frag(struct i40e_ring *rx_ring,
* i40e_fetch_rx_buffer - Allocate skb and populate it
* @rx_ring: rx descriptor ring to transact packets on
* @rx_desc: descriptor containing info written by hardware
+ * @size: size of buffer to add to skb
*
* This function allocates an skb on the fly, and populates it with the page
* data from the current receive descriptor, taking care to set up the skb
@@ -1766,13 +1767,9 @@ static bool i40e_add_rx_frag(struct i40e_ring *rx_ring,
static inline
struct sk_buff *i40e_fetch_rx_buffer(struct i40e_ring *rx_ring,
union i40e_rx_desc *rx_desc,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ unsigned int size)
{
- u64 local_status_error_len =
- le64_to_cpu(rx_desc->wb.qword1.status_error_len);
- unsigned int size =
- (local_status_error_len & I40E_RXD_QW1_LENGTH_PBUF_MASK) >>
- I40E_RXD_QW1_LENGTH_PBUF_SHIFT;
struct i40e_rx_buffer *rx_buffer;
struct page *page;
@@ -1890,6 +1887,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
while (likely(total_rx_packets < budget)) {
union i40e_rx_desc *rx_desc;
+ unsigned int size;
u16 vlan_tag;
u8 rx_ptype;
u64 qword;
@@ -1906,19 +1904,21 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
/* status_error_len will always be zero for unused descriptors
* because it's cleared in cleanup, and overlaps with hdr_addr
* which is always zero because packet split isn't used, if the
- * hardware wrote DD then it will be non-zero
+ * hardware wrote DD then the length will be non-zero
*/
- if (!i40e_test_staterr(rx_desc,
- BIT(I40E_RX_DESC_STATUS_DD_SHIFT)))
+ qword = le64_to_cpu(rx_desc->wb.qword1.status_error_len);
+ size = (qword & I40E_RXD_QW1_LENGTH_PBUF_MASK) >>
+ I40E_RXD_QW1_LENGTH_PBUF_SHIFT;
+ if (!size)
break;
/* This memory barrier is needed to keep us from reading
- * any other fields out of the rx_desc until we know the
- * DD bit is set.
+ * any other fields out of the rx_desc until we have
+ * verified the descriptor has been written back.
*/
dma_rmb();
- skb = i40e_fetch_rx_buffer(rx_ring, rx_desc, skb);
+ skb = i40e_fetch_rx_buffer(rx_ring, rx_desc, skb, size);
if (!skb)
break;
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
index f1a99a8dc7ea..e41eb46b02fe 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -1116,6 +1116,7 @@ static bool i40e_add_rx_frag(struct i40e_ring *rx_ring,
* i40evf_fetch_rx_buffer - Allocate skb and populate it
* @rx_ring: rx descriptor ring to transact packets on
* @rx_desc: descriptor containing info written by hardware
+ * @size: size of buffer to add to skb
*
* This function allocates an skb on the fly, and populates it with the page
* data from the current receive descriptor, taking care to set up the skb
@@ -1125,13 +1126,9 @@ static bool i40e_add_rx_frag(struct i40e_ring *rx_ring,
static inline
struct sk_buff *i40evf_fetch_rx_buffer(struct i40e_ring *rx_ring,
union i40e_rx_desc *rx_desc,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ unsigned int size)
{
- u64 local_status_error_len =
- le64_to_cpu(rx_desc->wb.qword1.status_error_len);
- unsigned int size =
- (local_status_error_len & I40E_RXD_QW1_LENGTH_PBUF_MASK) >>
- I40E_RXD_QW1_LENGTH_PBUF_SHIFT;
struct i40e_rx_buffer *rx_buffer;
struct page *page;
@@ -1244,6 +1241,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
while (likely(total_rx_packets < budget)) {
union i40e_rx_desc *rx_desc;
+ unsigned int size;
u16 vlan_tag;
u8 rx_ptype;
u64 qword;
@@ -1260,19 +1258,21 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
/* status_error_len will always be zero for unused descriptors
* because it's cleared in cleanup, and overlaps with hdr_addr
* which is always zero because packet split isn't used, if the
- * hardware wrote DD then it will be non-zero
+ * hardware wrote DD then the length will be non-zero
*/
- if (!i40e_test_staterr(rx_desc,
- BIT(I40E_RX_DESC_STATUS_DD_SHIFT)))
+ qword = le64_to_cpu(rx_desc->wb.qword1.status_error_len);
+ size = (qword & I40E_RXD_QW1_LENGTH_PBUF_MASK) >>
+ I40E_RXD_QW1_LENGTH_PBUF_SHIFT;
+ if (!size)
break;
/* This memory barrier is needed to keep us from reading
- * any other fields out of the rx_desc until we know the
- * DD bit is set.
+ * any other fields out of the rx_desc until we have
+ * verified the descriptor has been written back.
*/
dma_rmb();
- skb = i40evf_fetch_rx_buffer(rx_ring, rx_desc, skb);
+ skb = i40evf_fetch_rx_buffer(rx_ring, rx_desc, skb, size);
if (!skb)
break;
--
2.12.0
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