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net, thunderx: Remove unnecessary rcv buffer start address management
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Since we have moved on to using allocated pages to carve receive
buffers instead of netdev_alloc_skb() there is no need to store
any pointers for later retrieval. Earlier we had to store
skb and skb->data pointers which later are used to handover
received packet to network stack.

This will avoid an unnecessary cache miss as well.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Sunil Goutham authored and David S. Miller committed Dec 7, 2015
1 parent b45ceb4 commit 668dda0
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Showing 2 changed files with 11 additions and 48 deletions.
49 changes: 9 additions & 40 deletions drivers/net/ethernet/cavium/thunder/nicvf_queues.c
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Original file line number Diff line number Diff line change
Expand Up @@ -18,14 +18,6 @@
#include "q_struct.h"
#include "nicvf_queues.h"

struct rbuf_info {
struct page *page;
void *data;
u64 offset;
};

#define GET_RBUF_INFO(x) ((struct rbuf_info *)(x - NICVF_RCV_BUF_ALIGN_BYTES))

/* Poll a register for a specific value */
static int nicvf_poll_reg(struct nicvf *nic, int qidx,
u64 reg, int bit_pos, int bits, int val)
Expand Down Expand Up @@ -86,8 +78,6 @@ static void nicvf_free_q_desc_mem(struct nicvf *nic, struct q_desc_mem *dmem)
static inline int nicvf_alloc_rcv_buffer(struct nicvf *nic, gfp_t gfp,
u32 buf_len, u64 **rbuf)
{
u64 data;
struct rbuf_info *rinfo;
int order = get_order(buf_len);

/* Check if request can be accomodated in previous allocated page */
Expand All @@ -113,46 +103,28 @@ static inline int nicvf_alloc_rcv_buffer(struct nicvf *nic, gfp_t gfp,
nic->rb_page_offset = 0;
}

data = (u64)page_address(nic->rb_page) + nic->rb_page_offset;

/* Align buffer addr to cache line i.e 128 bytes */
rinfo = (struct rbuf_info *)(data + NICVF_RCV_BUF_ALIGN_LEN(data));
/* Save page address for reference updation */
rinfo->page = nic->rb_page;
/* Store start address for later retrieval */
rinfo->data = (void *)data;
/* Store alignment offset */
rinfo->offset = NICVF_RCV_BUF_ALIGN_LEN(data);
*rbuf = (u64 *)((u64)page_address(nic->rb_page) + nic->rb_page_offset);

data += rinfo->offset;

/* Give next aligned address to hw for DMA */
*rbuf = (u64 *)(data + NICVF_RCV_BUF_ALIGN_BYTES);
return 0;
}

/* Retrieve actual buffer start address and build skb for received packet */
/* Build skb around receive buffer */
static struct sk_buff *nicvf_rb_ptr_to_skb(struct nicvf *nic,
u64 rb_ptr, int len)
{
void *data;
struct sk_buff *skb;
struct rbuf_info *rinfo;

rb_ptr = (u64)phys_to_virt(rb_ptr);
/* Get buffer start address and alignment offset */
rinfo = GET_RBUF_INFO(rb_ptr);
data = phys_to_virt(rb_ptr);

/* Now build an skb to give to stack */
skb = build_skb(rinfo->data, RCV_FRAG_LEN);
skb = build_skb(data, RCV_FRAG_LEN);
if (!skb) {
put_page(rinfo->page);
put_page(virt_to_page(data));
return NULL;
}

/* Set correct skb->data */
skb_reserve(skb, rinfo->offset + NICVF_RCV_BUF_ALIGN_BYTES);

prefetch((void *)rb_ptr);
prefetch(skb->data);
return skb;
}

Expand Down Expand Up @@ -196,7 +168,6 @@ static void nicvf_free_rbdr(struct nicvf *nic, struct rbdr *rbdr)
int head, tail;
u64 buf_addr;
struct rbdr_entry_t *desc;
struct rbuf_info *rinfo;

if (!rbdr)
return;
Expand All @@ -212,16 +183,14 @@ static void nicvf_free_rbdr(struct nicvf *nic, struct rbdr *rbdr)
while (head != tail) {
desc = GET_RBDR_DESC(rbdr, head);
buf_addr = desc->buf_addr << NICVF_RCV_BUF_ALIGN;
rinfo = GET_RBUF_INFO((u64)phys_to_virt(buf_addr));
put_page(rinfo->page);
put_page(virt_to_page(phys_to_virt(buf_addr)));
head++;
head &= (rbdr->dmem.q_len - 1);
}
/* Free SKB of tail desc */
desc = GET_RBDR_DESC(rbdr, tail);
buf_addr = desc->buf_addr << NICVF_RCV_BUF_ALIGN;
rinfo = GET_RBUF_INFO((u64)phys_to_virt(buf_addr));
put_page(rinfo->page);
put_page(virt_to_page(phys_to_virt(buf_addr)));

/* Free RBDR ring */
nicvf_free_q_desc_mem(nic, &rbdr->dmem);
Expand Down
10 changes: 2 additions & 8 deletions drivers/net/ethernet/cavium/thunder/nicvf_queues.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -83,10 +83,8 @@
#define MAX_RCV_BUF_COUNT (1ULL << (RBDR_SIZE6 + 13))
#define RBDR_THRESH (RCV_BUF_COUNT / 2)
#define DMA_BUFFER_LEN 2048 /* In multiples of 128bytes */
#define RCV_FRAG_LEN (SKB_DATA_ALIGN(DMA_BUFFER_LEN + NET_SKB_PAD) + \
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) + \
(NICVF_RCV_BUF_ALIGN_BYTES * 2))
#define RCV_DATA_OFFSET NICVF_RCV_BUF_ALIGN_BYTES
#define RCV_FRAG_LEN (SKB_DATA_ALIGN(DMA_BUFFER_LEN + NET_SKB_PAD) + \
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))

#define MAX_CQES_FOR_TX ((SND_QUEUE_LEN / MIN_SQ_DESC_PER_PKT_XMIT) * \
MAX_CQE_PER_PKT_XMIT)
Expand All @@ -108,10 +106,6 @@
#define NICVF_SQ_BASE_ALIGN_BYTES 128 /* 7 bits */

#define NICVF_ALIGNED_ADDR(ADDR, ALIGN_BYTES) ALIGN(ADDR, ALIGN_BYTES)
#define NICVF_ADDR_ALIGN_LEN(ADDR, BYTES)\
(NICVF_ALIGNED_ADDR(ADDR, BYTES) - BYTES)
#define NICVF_RCV_BUF_ALIGN_LEN(X)\
(NICVF_ALIGNED_ADDR(X, NICVF_RCV_BUF_ALIGN_BYTES) - X)

/* Queue enable/disable */
#define NICVF_SQ_EN BIT_ULL(19)
Expand Down

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