I modified the sky2 driver to do fragmented receive for large MTU.
The hardware supports breaking receive into chunks, so this version allocates
some header space in the skb data up to two pages (assuming 4K page size) for
the extra data.
It doesn't go into fragmented mode until it thinks the alloc_skb will cause
a order 1 allocation. For 1500 byte MTU the effective result is the same.
For systems with 64k pages there is no point in fragmenting.
The patch is part of a bigger set of changes, so it is really for comment
only at this point.
---
drivers/net/sky2.c | 293 ++++++++++++++++++++++++++++++++++++++---------------
drivers/net/sky2.h | 10 +
2 files changed, 221 insertions(+), 82 deletions(-)
--- sky2.orig/drivers/net/sky2.c 2006-09-01 14:16:23.000000000 -0700
+++ sky2/drivers/net/sky2.c 2006-09-01 14:16:24.000000000 -0700
@@ -50,19 +50,21 @@
#include "sky2.h"
#define DRV_NAME "sky2"
-#define DRV_VERSION "1.7"
+#define DRV_VERSION "1.10"
#define PFX DRV_NAME " "
/*
* 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.
+ * A transmit can require up to 40 ring elements (4 + 18 * 2)
+ * a jumbo receive requires 6 elements (3 * 2)
+ * Ring sizes must be a power of 2.
*/
-#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 +76,6 @@
#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 +91,7 @@
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");
@@ -814,12 +815,12 @@
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);
@@ -831,9 +832,52 @@
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
@@ -897,9 +941,7 @@
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;
}
@@ -980,38 +1022,57 @@
#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);
@@ -1024,27 +1085,54 @@
sky2_prefetch_init(hw, rxq, sky2->rx_le_map, RX_LE_SIZE - 1);
rx_set_checksum(sky2);
+
+ /* 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 2 allocation */
+ space = SKB_DATA_ALIGN(size) + 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++) {
- struct rx_ring_info *re = sky2->rx_ring + i;
+ re = sky2->rx_ring + i;
- re->skb = sky2_alloc_skb(sky2->netdev, sky2->rx_bufsize,
- GFP_KERNEL);
+ 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 {
@@ -1052,7 +1140,6 @@
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;
@@ -1770,15 +1857,6 @@
}
}
-
-/* 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);
@@ -1813,7 +1891,7 @@
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);
@@ -1839,9 +1917,93 @@
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,
@@ -1867,40 +2029,12 @@
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;
@@ -3153,7 +3287,6 @@
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;
--- sky2.orig/drivers/net/sky2.h 2006-09-01 14:16:23.000000000 -0700
+++ sky2/drivers/net/sky2.h 2006-09-01 14:16:24.000000000 -0700
@@ -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,
@@ -1791,7 +1793,9 @@
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 {
@@ -1817,7 +1821,9 @@
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;
--
VGER BF report: U 0.5
-
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