[PATCH 1/14] Spidernet DMA coalescing
Linas Vepstas
linas at austin.ibm.com
Thu Dec 14 08:06:59 EST 2006
The current driver code performs 512 DMA mappings of a bunch of
32-byte ring descriptor structures. This is silly, as they are
all in contiguous memory. This patch changes the code to
dma_map_coherent() each rx/tx ring as a whole.
Signed-off-by: Linas Vepstas <linas at austin.ibm.com>
Cc: James K Lewis <jklewis at us.ibm.com>
Cc: Arnd Bergmann <arnd at arndb.de>
----
drivers/net/spider_net.c | 103 +++++++++++++++++----------------------
drivers/net/spider_net.h | 17 +-----
drivers/net/spider_net_ethtool.c | 4 -
3 files changed, 54 insertions(+), 70 deletions(-)
Index: linux-2.6.19-git7/drivers/net/spider_net.c
===================================================================
--- linux-2.6.19-git7.orig/drivers/net/spider_net.c 2006-12-13 11:55:53.000000000 -0600
+++ linux-2.6.19-git7/drivers/net/spider_net.c 2006-12-13 13:04:04.000000000 -0600
@@ -280,72 +280,67 @@ spider_net_free_chain(struct spider_net_
{
struct spider_net_descr *descr;
- for (descr = chain->tail; !descr->bus_addr; descr = descr->next) {
- pci_unmap_single(card->pdev, descr->bus_addr,
- SPIDER_NET_DESCR_SIZE, PCI_DMA_BIDIRECTIONAL);
+ descr = chain->ring;
+ do {
descr->bus_addr = 0;
- }
+ descr->next_descr_addr = 0;
+ descr = descr->next;
+ } while (descr != chain->ring);
+
+ dma_free_coherent(&card->pdev->dev, chain->num_desc,
+ chain->ring, chain->dma_addr);
}
/**
- * spider_net_init_chain - links descriptor chain
+ * spider_net_init_chain - alloc and link descriptor chain
* @card: card structure
* @chain: address of chain
- * @start_descr: address of descriptor array
- * @no: number of descriptors
*
- * we manage a circular list that mirrors the hardware structure,
+ * We manage a circular list that mirrors the hardware structure,
* except that the hardware uses bus addresses.
*
- * returns 0 on success, <0 on failure
+ * Returns 0 on success, <0 on failure
*/
static int
spider_net_init_chain(struct spider_net_card *card,
- struct spider_net_descr_chain *chain,
- struct spider_net_descr *start_descr,
- int no)
+ struct spider_net_descr_chain *chain)
{
int i;
struct spider_net_descr *descr;
dma_addr_t buf;
+ size_t alloc_size;
- descr = start_descr;
- memset(descr, 0, sizeof(*descr) * no);
+ alloc_size = chain->num_desc * sizeof (struct spider_net_descr);
- /* set up the hardware pointers in each descriptor */
- for (i=0; i<no; i++, descr++) {
- descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
+ chain->ring = dma_alloc_coherent(&card->pdev->dev, alloc_size,
+ &chain->dma_addr, GFP_KERNEL);
- buf = pci_map_single(card->pdev, descr,
- SPIDER_NET_DESCR_SIZE,
- PCI_DMA_BIDIRECTIONAL);
+ if (!chain->ring)
+ return -ENOMEM;
- if (pci_dma_mapping_error(buf))
- goto iommu_error;
+ descr = chain->ring;
+ memset(descr, 0, alloc_size);
+
+ /* Set up the hardware pointers in each descriptor */
+ buf = chain->dma_addr;
+ for (i=0; i < chain->num_desc; i++, descr++) {
+ descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
descr->bus_addr = buf;
+ descr->next_descr_addr = 0;
descr->next = descr + 1;
descr->prev = descr - 1;
+ buf += sizeof(struct spider_net_descr);
}
/* do actual circular list */
- (descr-1)->next = start_descr;
- start_descr->prev = descr-1;
+ (descr-1)->next = chain->ring;
+ chain->ring->prev = descr-1;
spin_lock_init(&chain->lock);
- chain->head = start_descr;
- chain->tail = start_descr;
-
+ chain->head = chain->ring;
+ chain->tail = chain->ring;
return 0;
-
-iommu_error:
- descr = start_descr;
- for (i=0; i < no; i++, descr++)
- if (descr->bus_addr)
- pci_unmap_single(card->pdev, descr->bus_addr,
- SPIDER_NET_DESCR_SIZE,
- PCI_DMA_BIDIRECTIONAL);
- return -ENOMEM;
}
/**
@@ -707,7 +702,7 @@ spider_net_set_low_watermark(struct spid
}
/* If TX queue is short, don't even bother with interrupts */
- if (cnt < card->num_tx_desc/4)
+ if (cnt < card->tx_chain.num_desc/4)
return cnt;
/* Set low-watermark 3/4th's of the way into the queue. */
@@ -1652,26 +1647,25 @@ spider_net_open(struct net_device *netde
{
struct spider_net_card *card = netdev_priv(netdev);
struct spider_net_descr *descr;
- int i, result;
+ int result;
- result = -ENOMEM;
- if (spider_net_init_chain(card, &card->tx_chain, card->descr,
- card->num_tx_desc))
+ result = spider_net_init_chain(card, &card->tx_chain);
+ if (result)
goto alloc_tx_failed;
-
card->low_watermark = NULL;
- /* rx_chain is after tx_chain, so offset is descr + tx_count */
- if (spider_net_init_chain(card, &card->rx_chain,
- card->descr + card->num_tx_desc,
- card->num_rx_desc))
+ result = spider_net_init_chain(card, &card->rx_chain);
+ if (result)
goto alloc_rx_failed;
- descr = card->rx_chain.head;
- for (i=0; i < card->num_rx_desc; i++, descr++)
+ /* Make a ring of of bus addresses */
+ descr = card->rx_chain.ring;
+ do {
descr->next_descr_addr = descr->next->bus_addr;
+ descr = descr->next;
+ } while (descr != card->rx_chain.ring);
- /* allocate rx skbs */
+ /* Allocate rx skbs */
if (spider_net_alloc_rx_skbs(card))
goto alloc_skbs_failed;
@@ -1924,6 +1918,7 @@ spider_net_stop(struct net_device *netde
/* release chains */
spider_net_release_tx_chain(card, 1);
+ spider_net_free_rx_chain_contents(card);
spider_net_free_chain(card, &card->tx_chain);
spider_net_free_chain(card, &card->rx_chain);
@@ -2054,8 +2049,8 @@ spider_net_setup_netdev(struct spider_ne
card->options.rx_csum = SPIDER_NET_RX_CSUM_DEFAULT;
- card->num_tx_desc = tx_descriptors;
- card->num_rx_desc = rx_descriptors;
+ card->tx_chain.num_desc = tx_descriptors;
+ card->rx_chain.num_desc = rx_descriptors;
spider_net_setup_netdev_ops(netdev);
@@ -2104,12 +2099,8 @@ spider_net_alloc_card(void)
{
struct net_device *netdev;
struct spider_net_card *card;
- size_t alloc_size;
- alloc_size = sizeof (*card) +
- sizeof (struct spider_net_descr) * rx_descriptors +
- sizeof (struct spider_net_descr) * tx_descriptors;
- netdev = alloc_etherdev(alloc_size);
+ netdev = alloc_etherdev(sizeof(struct spider_net_card));
if (!netdev)
return NULL;
Index: linux-2.6.19-git7/drivers/net/spider_net.h
===================================================================
--- linux-2.6.19-git7.orig/drivers/net/spider_net.h 2006-12-13 11:55:53.000000000 -0600
+++ linux-2.6.19-git7/drivers/net/spider_net.h 2006-12-13 12:04:02.000000000 -0600
@@ -378,6 +378,9 @@ struct spider_net_descr_chain {
spinlock_t lock;
struct spider_net_descr *head;
struct spider_net_descr *tail;
+ struct spider_net_descr *ring;
+ int num_desc;
+ dma_addr_t dma_addr;
};
/* descriptor data_status bits */
@@ -397,8 +400,6 @@ struct spider_net_descr_chain {
* 701b8000 would be correct, but every packets gets that flag */
#define SPIDER_NET_DESTROY_RX_FLAGS 0x700b8000
-#define SPIDER_NET_DESCR_SIZE 32
-
/* this will be bigger some time */
struct spider_net_options {
int rx_csum; /* for rx: if 0 ip_summed=NONE,
@@ -441,25 +442,17 @@ struct spider_net_card {
struct spider_net_descr_chain rx_chain;
struct spider_net_descr *low_watermark;
- struct net_device_stats netdev_stats;
-
- struct spider_net_options options;
-
- spinlock_t intmask_lock;
struct tasklet_struct rxram_full_tl;
struct timer_list tx_timer;
-
struct work_struct tx_timeout_task;
atomic_t tx_timeout_task_counter;
wait_queue_head_t waitq;
/* for ethtool */
int msg_enable;
- int num_rx_desc;
- int num_tx_desc;
+ struct net_device_stats netdev_stats;
struct spider_net_extra_stats spider_stats;
-
- struct spider_net_descr descr[0];
+ struct spider_net_options options;
};
#define pr_err(fmt,arg...) \
Index: linux-2.6.19-git7/drivers/net/spider_net_ethtool.c
===================================================================
--- linux-2.6.19-git7.orig/drivers/net/spider_net_ethtool.c 2006-11-29 15:57:37.000000000 -0600
+++ linux-2.6.19-git7/drivers/net/spider_net_ethtool.c 2006-12-13 12:59:25.000000000 -0600
@@ -158,9 +158,9 @@ spider_net_ethtool_get_ringparam(struct
struct spider_net_card *card = netdev->priv;
ering->tx_max_pending = SPIDER_NET_TX_DESCRIPTORS_MAX;
- ering->tx_pending = card->num_tx_desc;
+ ering->tx_pending = card->tx_chain.num_desc;
ering->rx_max_pending = SPIDER_NET_RX_DESCRIPTORS_MAX;
- ering->rx_pending = card->num_rx_desc;
+ ering->rx_pending = card->rx_chain.num_desc;
}
static int spider_net_get_stats_count(struct net_device *netdev)
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