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[PATCH] sky2: fragmented receive for large MTU

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Use hardware support for chained receive to break up large frames
into multiple pages. This avoids having to do a mult-page allocation
that can fail on a busy system due to fragmented memory.

For normal size MTU, this code behaves the same.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This commit is contained in:
Stephen Hemminger 2006-09-26 11:57:43 -07:00 committed by Jeff Garzik
parent 2bb8c26242
commit 14d0263fea
2 changed files with 220 additions and 82 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

292
drivers/net/sky2.c
View file

@ -56,13 +56,12 @@
/*
* The Yukon II chipset takes 64 bit command blocks (called list elements)
* that are organized into three (receive, transmit, status) different rings
* similar to Tigon3. A transmit can require several elements;
* a receive requires one (or two if using 64 bit dma).
* similar to Tigon3.
*/
#define RX_LE_SIZE 512
#define RX_LE_SIZE 1024
#define RX_LE_BYTES (RX_LE_SIZE*sizeof(struct sky2_rx_le))
#define RX_MAX_PENDING (RX_LE_SIZE/2 - 2)
#define RX_MAX_PENDING (RX_LE_SIZE/6 - 2)
#define RX_DEF_PENDING RX_MAX_PENDING
#define RX_SKB_ALIGN 8
#define RX_BUF_WRITE 16
@ -74,7 +73,6 @@
#define STATUS_RING_SIZE 2048 /* 2 ports * (TX + 2*RX) */
#define STATUS_LE_BYTES (STATUS_RING_SIZE*sizeof(struct sky2_status_le))
#define ETH_JUMBO_MTU 9000
#define TX_WATCHDOG (5 * HZ)
#define NAPI_WEIGHT 64
#define PHY_RETRIES 1000
@ -90,7 +88,7 @@ static int debug = -1; /* defaults above */
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
static int copybreak __read_mostly = 256;
static int copybreak __read_mostly = 128;
module_param(copybreak, int, 0);
MODULE_PARM_DESC(copybreak, "Receive copy threshold");
@ -803,12 +801,12 @@ static inline u32 high32(dma_addr_t a)
return sizeof(a) > sizeof(u32) ? (a >> 16) >> 16 : 0;
}
/* Build description to hardware about buffer */
static void sky2_rx_add(struct sky2_port *sky2, dma_addr_t map)
/* Build description to hardware for one receive segment */
static void sky2_rx_add(struct sky2_port *sky2, u8 op,
dma_addr_t map, unsigned len)
{
struct sky2_rx_le *le;
u32 hi = high32(map);
u16 len = sky2->rx_bufsize;
if (sky2->rx_addr64 != hi) {
le = sky2_next_rx(sky2);
@ -820,9 +818,52 @@ static void sky2_rx_add(struct sky2_port *sky2, dma_addr_t map)
le = sky2_next_rx(sky2);
le->addr = cpu_to_le32((u32) map);
le->length = cpu_to_le16(len);
le->opcode = OP_PACKET | HW_OWNER;
le->opcode = op | HW_OWNER;
}
/* Build description to hardware for one possibly fragmented skb */
static void sky2_rx_submit(struct sky2_port *sky2,
const struct rx_ring_info *re)
{
int i;
sky2_rx_add(sky2, OP_PACKET, re->data_addr, sky2->rx_data_size);
for (i = 0; i < skb_shinfo(re->skb)->nr_frags; i++)
sky2_rx_add(sky2, OP_BUFFER, re->frag_addr[i], PAGE_SIZE);
}
static void sky2_rx_map_skb(struct pci_dev *pdev, struct rx_ring_info *re,
unsigned size)
{
struct sk_buff *skb = re->skb;
int i;
re->data_addr = pci_map_single(pdev, skb->data, size, PCI_DMA_FROMDEVICE);
pci_unmap_len_set(re, data_size, size);
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
re->frag_addr[i] = pci_map_page(pdev,
skb_shinfo(skb)->frags[i].page,
skb_shinfo(skb)->frags[i].page_offset,
skb_shinfo(skb)->frags[i].size,
PCI_DMA_FROMDEVICE);
}
static void sky2_rx_unmap_skb(struct pci_dev *pdev, struct rx_ring_info *re)
{
struct sk_buff *skb = re->skb;
int i;
pci_unmap_single(pdev, re->data_addr, pci_unmap_len(re, data_size),
PCI_DMA_FROMDEVICE);
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
pci_unmap_page(pdev, re->frag_addr[i],
skb_shinfo(skb)->frags[i].size,
PCI_DMA_FROMDEVICE);
}
/* Tell chip where to start receive checksum.
* Actually has two checksums, but set both same to avoid possible byte
@ -886,9 +927,7 @@ static void sky2_rx_clean(struct sky2_port *sky2)
struct rx_ring_info *re = sky2->rx_ring + i;
if (re->skb) {
pci_unmap_single(sky2->hw->pdev,
re->mapaddr, sky2->rx_bufsize,
PCI_DMA_FROMDEVICE);
sky2_rx_unmap_skb(sky2->hw->pdev, re);
kfree_skb(re->skb);
re->skb = NULL;
}
@ -969,38 +1008,57 @@ static void sky2_vlan_rx_kill_vid(struct net_device *dev, unsigned short vid)
#endif
/*
* Allocate an skb for receiving. If the MTU is large enough
* make the skb non-linear with a fragment list of pages.
*
* It appears the hardware has a bug in the FIFO logic that
* cause it to hang if the FIFO gets overrun and the receive buffer
* is not 64 byte aligned. The buffer returned from netdev_alloc_skb is
* aligned except if slab debugging is enabled.
*/
static inline struct sk_buff *sky2_alloc_skb(struct net_device *dev,
unsigned int length,
gfp_t gfp_mask)
static struct sk_buff *sky2_rx_alloc(struct sky2_port *sky2)
{
struct sk_buff *skb;
unsigned long p;
int i;
skb = __netdev_alloc_skb(dev, length + RX_SKB_ALIGN, gfp_mask);
if (likely(skb)) {
unsigned long p = (unsigned long) skb->data;
skb_reserve(skb, ALIGN(p, RX_SKB_ALIGN) - p);
skb = netdev_alloc_skb(sky2->netdev, sky2->rx_data_size + RX_SKB_ALIGN);
if (!skb)
goto nomem;
p = (unsigned long) skb->data;
skb_reserve(skb, ALIGN(p, RX_SKB_ALIGN) - p);
for (i = 0; i < sky2->rx_nfrags; i++) {
struct page *page = alloc_page(GFP_ATOMIC);
if (!page)
goto free_partial;
skb_fill_page_desc(skb, i, page, 0, PAGE_SIZE);
}
return skb;
free_partial:
kfree_skb(skb);
nomem:
return NULL;
}
/*
* Allocate and setup receiver buffer pool.
* In case of 64 bit dma, there are 2X as many list elements
* available as ring entries
* and need to reserve one list element so we don't wrap around.
* Normal case this ends up creating one list element for skb
* in the receive ring. Worst case if using large MTU and each
* allocation falls on a different 64 bit region, that results
* in 6 list elements per ring entry.
* One element is used for checksum enable/disable, and one
* extra to avoid wrap.
*/
static int sky2_rx_start(struct sky2_port *sky2)
{
struct sky2_hw *hw = sky2->hw;
struct rx_ring_info *re;
unsigned rxq = rxqaddr[sky2->port];
int i;
unsigned thresh;
unsigned i, size, space, thresh;
sky2->rx_put = sky2->rx_next = 0;
sky2_qset(hw, rxq);
@ -1013,27 +1071,56 @@ static int sky2_rx_start(struct sky2_port *sky2)
sky2_prefetch_init(hw, rxq, sky2->rx_le_map, RX_LE_SIZE - 1);
rx_set_checksum(sky2);
for (i = 0; i < sky2->rx_pending; i++) {
struct rx_ring_info *re = sky2->rx_ring + i;
re->skb = sky2_alloc_skb(sky2->netdev, sky2->rx_bufsize,
GFP_KERNEL);
/* Space needed for frame data + headers rounded up */
size = ALIGN(sky2->netdev->mtu + ETH_HLEN + VLAN_HLEN, 8)
+ 8;
/* Stopping point for hardware truncation */
thresh = (size - 8) / sizeof(u32);
/* Account for overhead of skb - to avoid order > 0 allocation */
space = SKB_DATA_ALIGN(size) + NET_SKB_PAD
+ sizeof(struct skb_shared_info);
sky2->rx_nfrags = space >> PAGE_SHIFT;
BUG_ON(sky2->rx_nfrags > ARRAY_SIZE(re->frag_addr));
if (sky2->rx_nfrags != 0) {
/* Compute residue after pages */
space = sky2->rx_nfrags << PAGE_SHIFT;
if (space < size)
size -= space;
else
size = 0;
/* Optimize to handle small packets and headers */
if (size < copybreak)
size = copybreak;
if (size < ETH_HLEN)
size = ETH_HLEN;
}
sky2->rx_data_size = size;
/* Fill Rx ring */
for (i = 0; i < sky2->rx_pending; i++) {
re = sky2->rx_ring + i;
re->skb = sky2_rx_alloc(sky2);
if (!re->skb)
goto nomem;
re->mapaddr = pci_map_single(hw->pdev, re->skb->data,
sky2->rx_bufsize, PCI_DMA_FROMDEVICE);
sky2_rx_add(sky2, re->mapaddr);
sky2_rx_map_skb(hw->pdev, re, sky2->rx_data_size);
sky2_rx_submit(sky2, re);
}
/*
* The receiver hangs if it receives frames larger than the
* packet buffer. As a workaround, truncate oversize frames, but
* the register is limited to 9 bits, so if you do frames > 2052
* you better get the MTU right!
*/
thresh = (sky2->rx_bufsize - 8) / sizeof(u32);
if (thresh > 0x1ff)
sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_OFF);
else {
@ -1041,7 +1128,6 @@ static int sky2_rx_start(struct sky2_port *sky2)
sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_ON);
}
/* Tell chip about available buffers */
sky2_write16(hw, Y2_QADDR(rxq, PREF_UNIT_PUT_IDX), sky2->rx_put);
return 0;
@ -1743,15 +1829,6 @@ static void sky2_tx_timeout(struct net_device *dev)
}
}
/* Want receive buffer size to be multiple of 64 bits
* and incl room for vlan and truncation
*/
static inline unsigned sky2_buf_size(int mtu)
{
return ALIGN(mtu + ETH_HLEN + VLAN_HLEN, 8) + 8;
}
static int sky2_change_mtu(struct net_device *dev, int new_mtu)
{
struct sky2_port *sky2 = netdev_priv(dev);
@ -1786,7 +1863,7 @@ static int sky2_change_mtu(struct net_device *dev, int new_mtu)
sky2_rx_clean(sky2);
dev->mtu = new_mtu;
sky2->rx_bufsize = sky2_buf_size(new_mtu);
mode = DATA_BLIND_VAL(DATA_BLIND_DEF) |
GM_SMOD_VLAN_ENA | IPG_DATA_VAL(IPG_DATA_DEF);
@ -1812,9 +1889,93 @@ static int sky2_change_mtu(struct net_device *dev, int new_mtu)
return err;
}
/* For small just reuse existing skb for next receive */
static struct sk_buff *receive_copy(struct sky2_port *sky2,
const struct rx_ring_info *re,
unsigned length)
{
struct sk_buff *skb;
skb = netdev_alloc_skb(sky2->netdev, length + 2);
if (likely(skb)) {
skb_reserve(skb, 2);
pci_dma_sync_single_for_cpu(sky2->hw->pdev, re->data_addr,
length, PCI_DMA_FROMDEVICE);
memcpy(skb->data, re->skb->data, length);
skb->ip_summed = re->skb->ip_summed;
skb->csum = re->skb->csum;
pci_dma_sync_single_for_device(sky2->hw->pdev, re->data_addr,
length, PCI_DMA_FROMDEVICE);
re->skb->ip_summed = CHECKSUM_NONE;
__skb_put(skb, length);
}
return skb;
}
/* Adjust length of skb with fragments to match received data */
static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space,
unsigned int length)
{
int i, num_frags;
unsigned int size;
/* put header into skb */
size = min(length, hdr_space);
skb->tail += size;
skb->len += size;
length -= size;
num_frags = skb_shinfo(skb)->nr_frags;
for (i = 0; i < num_frags; i++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
if (length == 0) {
/* don't need this page */
__free_page(frag->page);
--skb_shinfo(skb)->nr_frags;
} else {
size = min(length, (unsigned) PAGE_SIZE);
frag->size = size;
skb->data_len += size;
skb->truesize += size;
skb->len += size;
length -= size;
}
}
}
/* Normal packet - take skb from ring element and put in a new one */
static struct sk_buff *receive_new(struct sky2_port *sky2,
struct rx_ring_info *re,
unsigned int length)
{
struct sk_buff *skb, *nskb;
unsigned hdr_space = sky2->rx_data_size;
pr_debug(PFX "receive new length=%d\n", length);
/* Don't be tricky about reusing pages (yet) */
nskb = sky2_rx_alloc(sky2);
if (unlikely(!nskb))
return NULL;
skb = re->skb;
sky2_rx_unmap_skb(sky2->hw->pdev, re);
prefetch(skb->data);
re->skb = nskb;
sky2_rx_map_skb(sky2->hw->pdev, re, hdr_space);
if (skb_shinfo(skb)->nr_frags)
skb_put_frags(skb, hdr_space, length);
else
skb_put(skb, hdr_space);
return skb;
}
/*
* Receive one packet.
* For small packets or errors, just reuse existing skb.
* For larger packets, get new buffer.
*/
static struct sk_buff *sky2_receive(struct net_device *dev,
@ -1840,40 +2001,12 @@ static struct sk_buff *sky2_receive(struct net_device *dev,
if (length > dev->mtu + ETH_HLEN)
goto oversize;
if (length < copybreak) {
skb = netdev_alloc_skb(dev, length + 2);
if (!skb)
goto resubmit;
skb_reserve(skb, 2);
pci_dma_sync_single_for_cpu(sky2->hw->pdev, re->mapaddr,
length, PCI_DMA_FROMDEVICE);
memcpy(skb->data, re->skb->data, length);
skb->ip_summed = re->skb->ip_summed;
skb->csum = re->skb->csum;
pci_dma_sync_single_for_device(sky2->hw->pdev, re->mapaddr,
length, PCI_DMA_FROMDEVICE);
} else {
struct sk_buff *nskb;
nskb = sky2_alloc_skb(dev, sky2->rx_bufsize, GFP_ATOMIC);
if (!nskb)
goto resubmit;
skb = re->skb;
re->skb = nskb;
pci_unmap_single(sky2->hw->pdev, re->mapaddr,
sky2->rx_bufsize, PCI_DMA_FROMDEVICE);
prefetch(skb->data);
re->mapaddr = pci_map_single(sky2->hw->pdev, nskb->data,
sky2->rx_bufsize, PCI_DMA_FROMDEVICE);
}
skb_put(skb, length);
if (length < copybreak)
skb = receive_copy(sky2, re, length);
else
skb = receive_new(sky2, re, length);
resubmit:
re->skb->ip_summed = CHECKSUM_NONE;
sky2_rx_add(sky2, re->mapaddr);
sky2_rx_submit(sky2, re);
return skb;
@ -3125,7 +3258,6 @@ static __devinit struct net_device *sky2_init_netdev(struct sky2_hw *hw,
spin_lock_init(&sky2->phy_lock);
sky2->tx_pending = TX_DEF_PENDING;
sky2->rx_pending = RX_DEF_PENDING;
sky2->rx_bufsize = sky2_buf_size(ETH_DATA_LEN);
hw->dev[port] = dev;

10
drivers/net/sky2.h
View file

@ -4,6 +4,8 @@
#ifndef _SKY2_H
#define _SKY2_H
#define ETH_JUMBO_MTU 9000 /* Maximum MTU supported */
/* PCI device specific config registers */
enum {
PCI_DEV_REG1 = 0x40,
@ -1779,7 +1781,9 @@ struct tx_ring_info {
struct rx_ring_info {
struct sk_buff *skb;
dma_addr_t mapaddr;
dma_addr_t data_addr;
DECLARE_PCI_UNMAP_ADDR(data_size);
dma_addr_t frag_addr[ETH_JUMBO_MTU >> PAGE_SHIFT];
};
struct sky2_port {
@ -1804,7 +1808,9 @@ struct sky2_port {
u16 rx_next; /* next re to check */
u16 rx_put; /* next le index to use */
u16 rx_pending;
u16 rx_bufsize;
u16 rx_data_size;
u16 rx_nfrags;
#ifdef SKY2_VLAN_TAG_USED
u16 rx_tag;
struct vlan_group *vlgrp;