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i40e/i40evf: Add support for padding start of frames 

This patch adds padding to the start of frames to make room for headroom
for us to eventually start using build_skb.  Right now we guarantee at
least NET_SKB_PAD + NET_IP_ALIGN, however we allocate more space if more is
available.  For example on x86 the headroom should be 192 bytes.

On systems that have too large of a cache line size to support storing 1.5K
padding and shared info we default to using 3K buffers and reserve
everything that isn't used for skb_shared_info or the data buffer for
headroom.

Change-ID: I33c641c9a1ea10cf7cc484c2d20985368d2d709a
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>
This commit is contained in:
Alexander Duyck 2017-04-05 07:51:02 -04:00 committed by Jeff Kirsher
parent 98efd69493
commit ca9ec0888d
6 changed files with 179 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/net/ethernet/intel/i40e/i40e_main.c
View File

@ -3038,6 +3038,12 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
return -ENOMEM;
}
/* configure Rx buffer alignment */
if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX))
clear_ring_build_skb_enabled(ring);
else
set_ring_build_skb_enabled(ring);
/* cache tail for quicker writes, and clear the reg before use */
ring->tail = hw->hw_addr + I40E_QRX_TAIL(pf_q);
writel(0, ring->tail);
@ -3079,7 +3085,8 @@ static int i40e_vsi_configure_rx(struct i40e_vsi *vsi)
vsi->max_frame = I40E_MAX_RXBUFFER;
vsi->rx_buf_len = I40E_RXBUFFER_2048;
#if (PAGE_SIZE < 8192)
} else if (vsi->netdev->mtu <= ETH_DATA_LEN) {
} else if (!I40E_2K_TOO_SMALL_WITH_PADDING &&
(vsi->netdev->mtu <= ETH_DATA_LEN)) {
vsi->max_frame = I40E_RXBUFFER_1536 - NET_IP_ALIGN;
vsi->rx_buf_len = I40E_RXBUFFER_1536 - NET_IP_ALIGN;
#endif

15
drivers/net/ethernet/intel/i40e/i40e_txrx.c
View File

@ -1247,6 +1247,17 @@ static inline void i40e_release_rx_desc(struct i40e_ring *rx_ring, u32 val)
writel(val, rx_ring->tail);
}
/**
* i40e_rx_offset - Return expected offset into page to access data
* @rx_ring: Ring we are requesting offset of
*
* Returns the offset value for ring into the data buffer.
*/
static inline unsigned int i40e_rx_offset(struct i40e_ring *rx_ring)
{
return ring_uses_build_skb(rx_ring) ? I40E_SKB_PAD : 0;
}
/**
* i40e_alloc_mapped_page - recycle or make a new page
* @rx_ring: ring to use
@ -1291,7 +1302,7 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
bi->dma = dma;
bi->page = page;
bi->page_offset = 0;
bi->page_offset = i40e_rx_offset(rx_ring);
/* initialize pagecnt_bias to 1 representing we fully own page */
bi->pagecnt_bias = 1;
@ -1696,7 +1707,7 @@ static void i40e_add_rx_frag(struct i40e_ring *rx_ring,
#if (PAGE_SIZE < 8192)
unsigned int truesize = i40e_rx_pg_size(rx_ring) / 2;
#else
unsigned int truesize = SKB_DATA_ALIGN(size);
unsigned int truesize = SKB_DATA_ALIGN(size + i40e_rx_offset(rx_ring));
#endif
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_buffer->page,

70
drivers/net/ethernet/intel/i40e/i40e_txrx.h
View File

@ -135,6 +135,58 @@ enum i40e_dyn_idx_t {
#define I40E_RX_DMA_ATTR \
(DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING)
/* Attempt to maximize the headroom available for incoming frames. We
* use a 2K buffer for receives and need 1536/1534 to store the data for
* the frame. This leaves us with 512 bytes of room. From that we need
* to deduct the space needed for the shared info and the padding needed
* to IP align the frame.
*
* Note: For cache line sizes 256 or larger this value is going to end
* up negative. In these cases we should fall back to the legacy
* receive path.
*/
#if (PAGE_SIZE < 8192)
#define I40E_2K_TOO_SMALL_WITH_PADDING \
((NET_SKB_PAD + I40E_RXBUFFER_1536) > SKB_WITH_OVERHEAD(I40E_RXBUFFER_2048))
static inline int i40e_compute_pad(int rx_buf_len)
{
int page_size, pad_size;
page_size = ALIGN(rx_buf_len, PAGE_SIZE / 2);
pad_size = SKB_WITH_OVERHEAD(page_size) - rx_buf_len;
return pad_size;
}
static inline int i40e_skb_pad(void)
{
int rx_buf_len;
/* If a 2K buffer cannot handle a standard Ethernet frame then
* optimize padding for a 3K buffer instead of a 1.5K buffer.
*
* For a 3K buffer we need to add enough padding to allow for
* tailroom due to NET_IP_ALIGN possibly shifting us out of
* cache-line alignment.
*/
if (I40E_2K_TOO_SMALL_WITH_PADDING)
rx_buf_len = I40E_RXBUFFER_3072 + SKB_DATA_ALIGN(NET_IP_ALIGN);
else
rx_buf_len = I40E_RXBUFFER_1536;
/* if needed make room for NET_IP_ALIGN */
rx_buf_len -= NET_IP_ALIGN;
return i40e_compute_pad(rx_buf_len);
}
#define I40E_SKB_PAD i40e_skb_pad()
#else
#define I40E_2K_TOO_SMALL_WITH_PADDING false
#define I40E_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN)
#endif
/**
* i40e_test_staterr - tests bits in Rx descriptor status and error fields
* @rx_desc: pointer to receive descriptor (in le64 format)
@ -341,7 +393,8 @@ struct i40e_ring {
u8 packet_stride;
u16 flags;
#define I40E_TXR_FLAGS_WB_ON_ITR BIT(0)
#define I40E_TXR_FLAGS_WB_ON_ITR BIT(0)
#define I40E_RXR_FLAGS_BUILD_SKB_ENABLED BIT(1)
/* stats structs */
struct i40e_queue_stats stats;
@ -369,6 +422,21 @@ struct i40e_ring {
*/
} ____cacheline_internodealigned_in_smp;
static inline bool ring_uses_build_skb(struct i40e_ring *ring)
{
return !!(ring->flags & I40E_RXR_FLAGS_BUILD_SKB_ENABLED);
}
static inline void set_ring_build_skb_enabled(struct i40e_ring *ring)
{
ring->flags |= I40E_RXR_FLAGS_BUILD_SKB_ENABLED;
}
static inline void clear_ring_build_skb_enabled(struct i40e_ring *ring)
{
ring->flags &= ~I40E_RXR_FLAGS_BUILD_SKB_ENABLED;
}
enum i40e_latency_range {
I40E_LOWEST_LATENCY = 0,
I40E_LOW_LATENCY = 1,

15
drivers/net/ethernet/intel/i40evf/i40e_txrx.c
View File

@ -618,6 +618,17 @@ static inline void i40e_release_rx_desc(struct i40e_ring *rx_ring, u32 val)
writel(val, rx_ring->tail);
}
/**
* i40e_rx_offset - Return expected offset into page to access data
* @rx_ring: Ring we are requesting offset of
*
* Returns the offset value for ring into the data buffer.
*/
static inline unsigned int i40e_rx_offset(struct i40e_ring *rx_ring)
{
return ring_uses_build_skb(rx_ring) ? I40E_SKB_PAD : 0;
}
/**
* i40e_alloc_mapped_page - recycle or make a new page
* @rx_ring: ring to use
@ -662,7 +673,7 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
bi->dma = dma;
bi->page = page;
bi->page_offset = 0;
bi->page_offset = i40e_rx_offset(rx_ring);
/* initialize pagecnt_bias to 1 representing we fully own page */
bi->pagecnt_bias = 1;
@ -1057,7 +1068,7 @@ static void i40e_add_rx_frag(struct i40e_ring *rx_ring,
#if (PAGE_SIZE < 8192)
unsigned int truesize = i40e_rx_pg_size(rx_ring) / 2;
#else
unsigned int truesize = SKB_DATA_ALIGN(size);
unsigned int truesize = SKB_DATA_ALIGN(size + i40e_rx_offset(rx_ring));
#endif
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_buffer->page,

70
drivers/net/ethernet/intel/i40evf/i40e_txrx.h
View File

@ -122,6 +122,58 @@ enum i40e_dyn_idx_t {
#define I40E_RX_DMA_ATTR \
(DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING)
/* Attempt to maximize the headroom available for incoming frames. We
* use a 2K buffer for receives and need 1536/1534 to store the data for
* the frame. This leaves us with 512 bytes of room. From that we need
* to deduct the space needed for the shared info and the padding needed
* to IP align the frame.
*
* Note: For cache line sizes 256 or larger this value is going to end
* up negative. In these cases we should fall back to the legacy
* receive path.
*/
#if (PAGE_SIZE < 8192)
#define I40E_2K_TOO_SMALL_WITH_PADDING \
((NET_SKB_PAD + I40E_RXBUFFER_1536) > SKB_WITH_OVERHEAD(I40E_RXBUFFER_2048))
static inline int i40e_compute_pad(int rx_buf_len)
{
int page_size, pad_size;
page_size = ALIGN(rx_buf_len, PAGE_SIZE / 2);
pad_size = SKB_WITH_OVERHEAD(page_size) - rx_buf_len;
return pad_size;
}
static inline int i40e_skb_pad(void)
{
int rx_buf_len;
/* If a 2K buffer cannot handle a standard Ethernet frame then
* optimize padding for a 3K buffer instead of a 1.5K buffer.
*
* For a 3K buffer we need to add enough padding to allow for
* tailroom due to NET_IP_ALIGN possibly shifting us out of
* cache-line alignment.
*/
if (I40E_2K_TOO_SMALL_WITH_PADDING)
rx_buf_len = I40E_RXBUFFER_3072 + SKB_DATA_ALIGN(NET_IP_ALIGN);
else
rx_buf_len = I40E_RXBUFFER_1536;
/* if needed make room for NET_IP_ALIGN */
rx_buf_len -= NET_IP_ALIGN;
return i40e_compute_pad(rx_buf_len);
}
#define I40E_SKB_PAD i40e_skb_pad()
#else
#define I40E_2K_TOO_SMALL_WITH_PADDING false
#define I40E_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN)
#endif
/**
* i40e_test_staterr - tests bits in Rx descriptor status and error fields
* @rx_desc: pointer to receive descriptor (in le64 format)
@ -328,7 +380,8 @@ struct i40e_ring {
u8 packet_stride;
u16 flags;
#define I40E_TXR_FLAGS_WB_ON_ITR BIT(0)
#define I40E_TXR_FLAGS_WB_ON_ITR BIT(0)
#define I40E_RXR_FLAGS_BUILD_SKB_ENABLED BIT(1)
/* stats structs */
struct i40e_queue_stats stats;
@ -356,6 +409,21 @@ struct i40e_ring {
*/
} ____cacheline_internodealigned_in_smp;
static inline bool ring_uses_build_skb(struct i40e_ring *ring)
{
return !!(ring->flags & I40E_RXR_FLAGS_BUILD_SKB_ENABLED);
}
static inline void set_ring_build_skb_enabled(struct i40e_ring *ring)
{
ring->flags |= I40E_RXR_FLAGS_BUILD_SKB_ENABLED;
}
static inline void clear_ring_build_skb_enabled(struct i40e_ring *ring)
{
ring->flags &= ~I40E_RXR_FLAGS_BUILD_SKB_ENABLED;
}
enum i40e_latency_range {
I40E_LOWEST_LATENCY = 0,
I40E_LOW_LATENCY = 1,

8
drivers/net/ethernet/intel/i40evf/i40evf_main.c
View File

@ -704,7 +704,8 @@ static void i40evf_configure_rx(struct i40evf_adapter *adapter)
* standard Ethernet mtu. On x86 this gives us enough room
* for shared info and 192 bytes of padding.
*/
if (netdev->mtu <= ETH_DATA_LEN)
if (!I40E_2K_TOO_SMALL_WITH_PADDING &&
(netdev->mtu <= ETH_DATA_LEN))
rx_buf_len = I40E_RXBUFFER_1536 - NET_IP_ALIGN;
}
#endif
@ -712,6 +713,11 @@ static void i40evf_configure_rx(struct i40evf_adapter *adapter)
for (i = 0; i < adapter->num_active_queues; i++) {
adapter->rx_rings[i].tail = hw->hw_addr + I40E_QRX_TAIL1(i);
adapter->rx_rings[i].rx_buf_len = rx_buf_len;
if (adapter->flags & I40EVF_FLAG_LEGACY_RX)
clear_ring_build_skb_enabled(&adapter->rx_rings[i]);
else
set_ring_build_skb_enabled(&adapter->rx_rings[i]);
}
}