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i40e/i40evf: Pull code for grabbing and syncing rx_buffer from fetch_…
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…buffer

This patch pulls the code responsible for fetching the Rx buffer and
synchronizing DMA into a function, specifically called i40e_get_rx_buffer.

The general idea is to allow for better code reuse by pulling this out of
i40e_fetch_rx_buffer.  We dropped a couple of prefetches since the time
between the prefetch being called and the data being accessed was too small
to be useful.

Change-ID: I4885fce4b2637dbedc8e16431169d23d3d7e79b9
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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Alexander Duyck authored and Jeff Kirsher committed Mar 29, 2017
1 parent d57c0e0 commit 9a06412
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Showing 2 changed files with 68 additions and 48 deletions.
58 changes: 34 additions & 24 deletions drivers/net/ethernet/intel/i40e/i40e_txrx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1753,10 +1753,36 @@ static bool i40e_add_rx_frag(struct i40e_ring *rx_ring,
return i40e_can_reuse_rx_page(rx_buffer, page, truesize);
}

/**
* i40e_get_rx_buffer - Fetch Rx buffer and synchronize data for use
* @rx_ring: rx descriptor ring to transact packets on
* @size: size of buffer to add to skb
*
* This function will pull an Rx buffer from the ring and synchronize it
* for use by the CPU.
*/
static struct i40e_rx_buffer *i40e_get_rx_buffer(struct i40e_ring *rx_ring,
const unsigned int size)
{
struct i40e_rx_buffer *rx_buffer;

rx_buffer = &rx_ring->rx_bi[rx_ring->next_to_clean];
prefetchw(rx_buffer->page);

/* we are reusing so sync this buffer for CPU use */
dma_sync_single_range_for_cpu(rx_ring->dev,
rx_buffer->dma,
rx_buffer->page_offset,
size,
DMA_FROM_DEVICE);

return rx_buffer;
}

/**
* 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
* @rx_buffer: rx buffer to pull data from
* @size: size of buffer to add to skb
*
* This function allocates an skb on the fly, and populates it with the page
Expand All @@ -1766,19 +1792,13 @@ 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 i40e_rx_buffer *rx_buffer,
struct sk_buff *skb,
unsigned int size)
{
struct i40e_rx_buffer *rx_buffer;
struct page *page;

rx_buffer = &rx_ring->rx_bi[rx_ring->next_to_clean];
page = rx_buffer->page;
prefetchw(page);

if (likely(!skb)) {
void *page_addr = page_address(page) + rx_buffer->page_offset;
void *page_addr = page_address(rx_buffer->page) +
rx_buffer->page_offset;

/* prefetch first cache line of first page */
prefetch(page_addr);
Expand All @@ -1794,21 +1814,8 @@ struct sk_buff *i40e_fetch_rx_buffer(struct i40e_ring *rx_ring,
rx_ring->rx_stats.alloc_buff_failed++;
return NULL;
}

/* we will be copying header into skb->data in
* pskb_may_pull so it is in our interest to prefetch
* it now to avoid a possible cache miss
*/
prefetchw(skb->data);
}

/* we are reusing so sync this buffer for CPU use */
dma_sync_single_range_for_cpu(rx_ring->dev,
rx_buffer->dma,
rx_buffer->page_offset,
size,
DMA_FROM_DEVICE);

/* pull page into skb */
if (i40e_add_rx_frag(rx_ring, rx_buffer, size, skb)) {
/* hand second half of page back to the ring */
Expand Down Expand Up @@ -1886,6 +1893,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
bool failure = false;

while (likely(total_rx_packets < budget)) {
struct i40e_rx_buffer *rx_buffer;
union i40e_rx_desc *rx_desc;
unsigned int size;
u16 vlan_tag;
Expand Down Expand Up @@ -1918,7 +1926,9 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
*/
dma_rmb();

skb = i40e_fetch_rx_buffer(rx_ring, rx_desc, skb, size);
rx_buffer = i40e_get_rx_buffer(rx_ring, size);

skb = i40e_fetch_rx_buffer(rx_ring, rx_buffer, skb, size);
if (!skb)
break;

Expand Down
58 changes: 34 additions & 24 deletions drivers/net/ethernet/intel/i40evf/i40e_txrx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1112,10 +1112,36 @@ static bool i40e_add_rx_frag(struct i40e_ring *rx_ring,
return i40e_can_reuse_rx_page(rx_buffer, page, truesize);
}

/**
* i40e_get_rx_buffer - Fetch Rx buffer and synchronize data for use
* @rx_ring: rx descriptor ring to transact packets on
* @size: size of buffer to add to skb
*
* This function will pull an Rx buffer from the ring and synchronize it
* for use by the CPU.
*/
static struct i40e_rx_buffer *i40e_get_rx_buffer(struct i40e_ring *rx_ring,
const unsigned int size)
{
struct i40e_rx_buffer *rx_buffer;

rx_buffer = &rx_ring->rx_bi[rx_ring->next_to_clean];
prefetchw(rx_buffer->page);

/* we are reusing so sync this buffer for CPU use */
dma_sync_single_range_for_cpu(rx_ring->dev,
rx_buffer->dma,
rx_buffer->page_offset,
size,
DMA_FROM_DEVICE);

return rx_buffer;
}

/**
* 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
* @rx_buffer: rx buffer to pull data from
* @size: size of buffer to add to skb
*
* This function allocates an skb on the fly, and populates it with the page
Expand All @@ -1125,19 +1151,13 @@ 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 i40e_rx_buffer *rx_buffer,
struct sk_buff *skb,
unsigned int size)
{
struct i40e_rx_buffer *rx_buffer;
struct page *page;

rx_buffer = &rx_ring->rx_bi[rx_ring->next_to_clean];
page = rx_buffer->page;
prefetchw(page);

if (likely(!skb)) {
void *page_addr = page_address(page) + rx_buffer->page_offset;
void *page_addr = page_address(rx_buffer->page) +
rx_buffer->page_offset;

/* prefetch first cache line of first page */
prefetch(page_addr);
Expand All @@ -1153,21 +1173,8 @@ struct sk_buff *i40evf_fetch_rx_buffer(struct i40e_ring *rx_ring,
rx_ring->rx_stats.alloc_buff_failed++;
return NULL;
}

/* we will be copying header into skb->data in
* pskb_may_pull so it is in our interest to prefetch
* it now to avoid a possible cache miss
*/
prefetchw(skb->data);
}

/* we are reusing so sync this buffer for CPU use */
dma_sync_single_range_for_cpu(rx_ring->dev,
rx_buffer->dma,
rx_buffer->page_offset,
size,
DMA_FROM_DEVICE);

/* pull page into skb */
if (i40e_add_rx_frag(rx_ring, rx_buffer, size, skb)) {
/* hand second half of page back to the ring */
Expand Down Expand Up @@ -1240,6 +1247,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
bool failure = false;

while (likely(total_rx_packets < budget)) {
struct i40e_rx_buffer *rx_buffer;
union i40e_rx_desc *rx_desc;
unsigned int size;
u16 vlan_tag;
Expand Down Expand Up @@ -1272,7 +1280,9 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
*/
dma_rmb();

skb = i40evf_fetch_rx_buffer(rx_ring, rx_desc, skb, size);
rx_buffer = i40e_get_rx_buffer(rx_ring, size);

skb = i40evf_fetch_rx_buffer(rx_ring, rx_buffer, skb, size);
if (!skb)
break;

Expand Down

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