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tg3: provide frags as skb head 

This patch converts tg3 driver, one of our reference drivers, to use new
build_skb() api in frag mode.

Instead of using kmalloc() to allocate the memory block that will be
used by build_skb() as skb->head, we use a page fragment.

This is a followup of patch "net: allow skb->head to be a page fragment"

This allows GRO, TCP coalescing, and splice() to be more efficient.

Incidentally, this also removes SLUB slow path contention in kfree()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-04-27 00:34:49 +00:00 committed by David S. Miller
parent d3836f21b0
commit 8d4057a938
2 changed files with 66 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

74
drivers/net/ethernet/broadcom/tg3.c
View File

@ -195,6 +195,15 @@ static inline void _tg3_flag_clear(enum TG3_FLAGS flag, unsigned long *bits)
#define TG3_RX_OFFSET(tp) (NET_SKB_PAD)
#endif
/* This driver uses the new build_skb() API providing a frag as skb->head
* This strategy permits better GRO aggregation, better TCP coalescing, and
* better splice() implementation (avoids a copy from head to a page), at
* minimal memory cost.
* In this 2048 bytes block, we have enough room to store the MTU=1500 frame
* and the struct skb_shared_info.
*/
#define TG3_FRAGSIZE 2048
/* minimum number of free TX descriptors required to wake up TX process */
#define TG3_TX_WAKEUP_THRESH(tnapi) ((tnapi)->tx_pending / 4)
#define TG3_TX_BD_DMA_MAX_2K 2048
@ -5617,17 +5626,48 @@ static void tg3_tx(struct tg3_napi *tnapi)
}
}
static void *tg3_frag_alloc(struct tg3_rx_prodring_set *tpr)
{
void *data;
if (tpr->rx_page_size < TG3_FRAGSIZE) {
struct page *page = alloc_page(GFP_ATOMIC);
if (!page)
return NULL;
atomic_add((PAGE_SIZE / TG3_FRAGSIZE) - 1, &page->_count);
tpr->rx_page_addr = page_address(page);
tpr->rx_page_size = PAGE_SIZE;
}
data = tpr->rx_page_addr;
tpr->rx_page_addr += TG3_FRAGSIZE;
tpr->rx_page_size -= TG3_FRAGSIZE;
return data;
}
static void tg3_frag_free(bool is_frag, void *data)
{
if (is_frag)
put_page(virt_to_head_page(data));
else
kfree(data);
}
static void tg3_rx_data_free(struct tg3 *tp, struct ring_info *ri, u32 map_sz)
{
unsigned int skb_size = SKB_DATA_ALIGN(map_sz + TG3_RX_OFFSET(tp)) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
if (!ri->data)
return;
pci_unmap_single(tp->pdev, dma_unmap_addr(ri, mapping),
map_sz, PCI_DMA_FROMDEVICE);
kfree(ri->data);
tg3_frag_free(skb_size <= TG3_FRAGSIZE, ri->data);
ri->data = NULL;
}
/* Returns size of skb allocated or < 0 on error.
*
* We only need to fill in the address because the other members
@ -5640,7 +5680,8 @@ static void tg3_rx_data_free(struct tg3 *tp, struct ring_info *ri, u32 map_sz)
* (to fetch the error flags, vlan tag, checksum, and opaque cookie).
*/
static int tg3_alloc_rx_data(struct tg3 *tp, struct tg3_rx_prodring_set *tpr,
u32 opaque_key, u32 dest_idx_unmasked)
u32 opaque_key, u32 dest_idx_unmasked,
unsigned int *frag_size)
{
struct tg3_rx_buffer_desc *desc;
struct ring_info *map;
@ -5675,7 +5716,13 @@ static int tg3_alloc_rx_data(struct tg3 *tp, struct tg3_rx_prodring_set *tpr,
*/
skb_size = SKB_DATA_ALIGN(data_size + TG3_RX_OFFSET(tp)) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
data = kmalloc(skb_size, GFP_ATOMIC);
if (skb_size <= TG3_FRAGSIZE) {
data = tg3_frag_alloc(tpr);
*frag_size = TG3_FRAGSIZE;
} else {
data = kmalloc(skb_size, GFP_ATOMIC);
*frag_size = 0;
}
if (!data)
return -ENOMEM;
@ -5683,8 +5730,8 @@ static int tg3_alloc_rx_data(struct tg3 *tp, struct tg3_rx_prodring_set *tpr,
data + TG3_RX_OFFSET(tp),
data_size,
PCI_DMA_FROMDEVICE);
if (pci_dma_mapping_error(tp->pdev, mapping)) {
kfree(data);
if (unlikely(pci_dma_mapping_error(tp->pdev, mapping))) {
tg3_frag_free(skb_size <= TG3_FRAGSIZE, data);
return -EIO;
}
@ -5835,18 +5882,19 @@ static int tg3_rx(struct tg3_napi *tnapi, int budget)
if (len > TG3_RX_COPY_THRESH(tp)) {
int skb_size;
unsigned int frag_size;
skb_size = tg3_alloc_rx_data(tp, tpr, opaque_key,
*post_ptr);
*post_ptr, &frag_size);
if (skb_size < 0)
goto drop_it;
pci_unmap_single(tp->pdev, dma_addr, skb_size,
PCI_DMA_FROMDEVICE);
skb = build_skb(data, 0);
skb = build_skb(data, frag_size);
if (!skb) {
kfree(data);
tg3_frag_free(frag_size != 0, data);
goto drop_it_no_recycle;
}
skb_reserve(skb, TG3_RX_OFFSET(tp));
@ -7279,7 +7327,10 @@ static int tg3_rx_prodring_alloc(struct tg3 *tp,
/* Now allocate fresh SKBs for each rx ring. */
for (i = 0; i < tp->rx_pending; i++) {
if (tg3_alloc_rx_data(tp, tpr, RXD_OPAQUE_RING_STD, i) < 0) {
unsigned int frag_size;
if (tg3_alloc_rx_data(tp, tpr, RXD_OPAQUE_RING_STD, i,
&frag_size) < 0) {
netdev_warn(tp->dev,
"Using a smaller RX standard ring. Only "
"%d out of %d buffers were allocated "
@ -7311,7 +7362,10 @@ static int tg3_rx_prodring_alloc(struct tg3 *tp,
}
for (i = 0; i < tp->rx_jumbo_pending; i++) {
if (tg3_alloc_rx_data(tp, tpr, RXD_OPAQUE_RING_JUMBO, i) < 0) {
unsigned int frag_size;
if (tg3_alloc_rx_data(tp, tpr, RXD_OPAQUE_RING_JUMBO, i,
&frag_size) < 0) {
netdev_warn(tp->dev,
"Using a smaller RX jumbo ring. Only %d "
"out of %d buffers were allocated "

2
drivers/net/ethernet/broadcom/tg3.h
View File

@ -2815,6 +2815,8 @@ struct tg3_rx_prodring_set {
struct ring_info *rx_jmb_buffers;
dma_addr_t rx_std_mapping;
dma_addr_t rx_jmb_mapping;
void *rx_page_addr;
unsigned int rx_page_size;
};
#define TG3_IRQ_MAX_VECS_RSS 5