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Date: Tue, 01 Mar 2011 01:21:30 +0000
From: Ben Hutchings <bhutchings@...arflare.com>
To: David Miller <davem@...emloft.net>
Cc: linux-net-drivers@...arflare.com, netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next-2.6] sfc: Reduce size of efx_rx_buffer by
unionising skb and page
From: Steve Hodgson <shodgson@...arflare.com>
[bwh: Forward-ported to net-next-2.6.]
Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
---
drivers/net/sfc/net_driver.h | 8 +++-
drivers/net/sfc/rx.c | 96 +++++++++++++++++++----------------------
2 files changed, 51 insertions(+), 53 deletions(-)
diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index 15b9068..59ff32a 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -216,13 +216,17 @@ struct efx_tx_queue {
* If both this and skb are %NULL, the buffer slot is currently free.
* @data: Pointer to ethernet header
* @len: Buffer length, in bytes.
+ * @is_page: Indicates if @page is valid. If false, @skb is valid.
*/
struct efx_rx_buffer {
dma_addr_t dma_addr;
- struct sk_buff *skb;
- struct page *page;
+ union {
+ struct sk_buff *skb;
+ struct page *page;
+ } u;
char *data;
unsigned int len;
+ bool is_page;
};
/**
diff --git a/drivers/net/sfc/rx.c b/drivers/net/sfc/rx.c
index 3925fd6..bcbd2ec 100644
--- a/drivers/net/sfc/rx.c
+++ b/drivers/net/sfc/rx.c
@@ -129,6 +129,7 @@ static int efx_init_rx_buffers_skb(struct efx_rx_queue *rx_queue)
struct efx_nic *efx = rx_queue->efx;
struct net_device *net_dev = efx->net_dev;
struct efx_rx_buffer *rx_buf;
+ struct sk_buff *skb;
int skb_len = efx->rx_buffer_len;
unsigned index, count;
@@ -136,24 +137,24 @@ static int efx_init_rx_buffers_skb(struct efx_rx_queue *rx_queue)
index = rx_queue->added_count & rx_queue->ptr_mask;
rx_buf = efx_rx_buffer(rx_queue, index);
- rx_buf->skb = netdev_alloc_skb(net_dev, skb_len);
- if (unlikely(!rx_buf->skb))
+ rx_buf->u.skb = skb = netdev_alloc_skb(net_dev, skb_len);
+ if (unlikely(!skb))
return -ENOMEM;
- rx_buf->page = NULL;
/* Adjust the SKB for padding and checksum */
- skb_reserve(rx_buf->skb, NET_IP_ALIGN);
+ skb_reserve(skb, NET_IP_ALIGN);
+ rx_buf->data = (char *)skb->data;
rx_buf->len = skb_len - NET_IP_ALIGN;
- rx_buf->data = (char *)rx_buf->skb->data;
- rx_buf->skb->ip_summed = CHECKSUM_UNNECESSARY;
+ rx_buf->is_page = false;
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
rx_buf->dma_addr = pci_map_single(efx->pci_dev,
rx_buf->data, rx_buf->len,
PCI_DMA_FROMDEVICE);
if (unlikely(pci_dma_mapping_error(efx->pci_dev,
rx_buf->dma_addr))) {
- dev_kfree_skb_any(rx_buf->skb);
- rx_buf->skb = NULL;
+ dev_kfree_skb_any(skb);
+ rx_buf->u.skb = NULL;
return -EIO;
}
@@ -211,10 +212,10 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue)
index = rx_queue->added_count & rx_queue->ptr_mask;
rx_buf = efx_rx_buffer(rx_queue, index);
rx_buf->dma_addr = dma_addr + EFX_PAGE_IP_ALIGN;
- rx_buf->skb = NULL;
- rx_buf->page = page;
+ rx_buf->u.page = page;
rx_buf->data = page_addr + EFX_PAGE_IP_ALIGN;
rx_buf->len = efx->rx_buffer_len - EFX_PAGE_IP_ALIGN;
+ rx_buf->is_page = true;
++rx_queue->added_count;
++rx_queue->alloc_page_count;
++state->refcnt;
@@ -235,19 +236,17 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue)
static void efx_unmap_rx_buffer(struct efx_nic *efx,
struct efx_rx_buffer *rx_buf)
{
- if (rx_buf->page) {
+ if (rx_buf->is_page && rx_buf->u.page) {
struct efx_rx_page_state *state;
- EFX_BUG_ON_PARANOID(rx_buf->skb);
-
- state = page_address(rx_buf->page);
+ state = page_address(rx_buf->u.page);
if (--state->refcnt == 0) {
pci_unmap_page(efx->pci_dev,
state->dma_addr,
efx_rx_buf_size(efx),
PCI_DMA_FROMDEVICE);
}
- } else if (likely(rx_buf->skb)) {
+ } else if (!rx_buf->is_page && rx_buf->u.skb) {
pci_unmap_single(efx->pci_dev, rx_buf->dma_addr,
rx_buf->len, PCI_DMA_FROMDEVICE);
}
@@ -256,12 +255,12 @@ static void efx_unmap_rx_buffer(struct efx_nic *efx,
static void efx_free_rx_buffer(struct efx_nic *efx,
struct efx_rx_buffer *rx_buf)
{
- if (rx_buf->page) {
- __free_pages(rx_buf->page, efx->rx_buffer_order);
- rx_buf->page = NULL;
- } else if (likely(rx_buf->skb)) {
- dev_kfree_skb_any(rx_buf->skb);
- rx_buf->skb = NULL;
+ if (rx_buf->is_page && rx_buf->u.page) {
+ __free_pages(rx_buf->u.page, efx->rx_buffer_order);
+ rx_buf->u.page = NULL;
+ } else if (!rx_buf->is_page && rx_buf->u.skb) {
+ dev_kfree_skb_any(rx_buf->u.skb);
+ rx_buf->u.skb = NULL;
}
}
@@ -277,7 +276,7 @@ static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue,
static void efx_resurrect_rx_buffer(struct efx_rx_queue *rx_queue,
struct efx_rx_buffer *rx_buf)
{
- struct efx_rx_page_state *state = page_address(rx_buf->page);
+ struct efx_rx_page_state *state = page_address(rx_buf->u.page);
struct efx_rx_buffer *new_buf;
unsigned fill_level, index;
@@ -292,16 +291,16 @@ static void efx_resurrect_rx_buffer(struct efx_rx_queue *rx_queue,
}
++state->refcnt;
- get_page(rx_buf->page);
+ get_page(rx_buf->u.page);
index = rx_queue->added_count & rx_queue->ptr_mask;
new_buf = efx_rx_buffer(rx_queue, index);
new_buf->dma_addr = rx_buf->dma_addr ^ (PAGE_SIZE >> 1);
- new_buf->skb = NULL;
- new_buf->page = rx_buf->page;
+ new_buf->u.page = rx_buf->u.page;
new_buf->data = (void *)
((__force unsigned long)rx_buf->data ^ (PAGE_SIZE >> 1));
new_buf->len = rx_buf->len;
+ new_buf->is_page = true;
++rx_queue->added_count;
}
@@ -315,16 +314,15 @@ static void efx_recycle_rx_buffer(struct efx_channel *channel,
struct efx_rx_buffer *new_buf;
unsigned index;
- if (rx_buf->page != NULL && efx->rx_buffer_len <= EFX_RX_HALF_PAGE &&
- page_count(rx_buf->page) == 1)
+ if (rx_buf->is_page && efx->rx_buffer_len <= EFX_RX_HALF_PAGE &&
+ page_count(rx_buf->u.page) == 1)
efx_resurrect_rx_buffer(rx_queue, rx_buf);
index = rx_queue->added_count & rx_queue->ptr_mask;
new_buf = efx_rx_buffer(rx_queue, index);
memcpy(new_buf, rx_buf, sizeof(*new_buf));
- rx_buf->page = NULL;
- rx_buf->skb = NULL;
+ rx_buf->u.page = NULL;
++rx_queue->added_count;
}
@@ -428,7 +426,7 @@ static void efx_rx_packet__check_len(struct efx_rx_queue *rx_queue,
* data at the end of the skb will be trashed. So
* we have no choice but to leak the fragment.
*/
- *leak_packet = (rx_buf->skb != NULL);
+ *leak_packet = !rx_buf->is_page;
efx_schedule_reset(efx, RESET_TYPE_RX_RECOVERY);
} else {
if (net_ratelimit())
@@ -454,13 +452,12 @@ static void efx_rx_packet_gro(struct efx_channel *channel,
gro_result_t gro_result;
/* Pass the skb/page into the GRO engine */
- if (rx_buf->page) {
+ if (rx_buf->is_page) {
struct efx_nic *efx = channel->efx;
- struct page *page = rx_buf->page;
+ struct page *page = rx_buf->u.page;
struct sk_buff *skb;
- EFX_BUG_ON_PARANOID(rx_buf->skb);
- rx_buf->page = NULL;
+ rx_buf->u.page = NULL;
skb = napi_get_frags(napi);
if (!skb) {
@@ -487,11 +484,10 @@ static void efx_rx_packet_gro(struct efx_channel *channel,
gro_result = napi_gro_frags(napi);
} else {
- struct sk_buff *skb = rx_buf->skb;
+ struct sk_buff *skb = rx_buf->u.skb;
- EFX_BUG_ON_PARANOID(!skb);
EFX_BUG_ON_PARANOID(!checksummed);
- rx_buf->skb = NULL;
+ rx_buf->u.skb = NULL;
gro_result = napi_gro_receive(napi, skb);
}
@@ -514,8 +510,6 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
rx_buf = efx_rx_buffer(rx_queue, index);
EFX_BUG_ON_PARANOID(!rx_buf->data);
- EFX_BUG_ON_PARANOID(rx_buf->skb && rx_buf->page);
- EFX_BUG_ON_PARANOID(!(rx_buf->skb || rx_buf->page));
/* This allows the refill path to post another buffer.
* EFX_RXD_HEAD_ROOM ensures that the slot we are using
@@ -587,32 +581,32 @@ void __efx_rx_packet(struct efx_channel *channel,
return;
}
- if (rx_buf->skb) {
- prefetch(skb_shinfo(rx_buf->skb));
+ if (!rx_buf->is_page) {
+ skb = rx_buf->u.skb;
+
+ prefetch(skb_shinfo(skb));
- skb_reserve(rx_buf->skb, efx->type->rx_buffer_hash_size);
- skb_put(rx_buf->skb, rx_buf->len);
+ skb_reserve(skb, efx->type->rx_buffer_hash_size);
+ skb_put(skb, rx_buf->len);
if (efx->net_dev->features & NETIF_F_RXHASH)
- rx_buf->skb->rxhash = efx_rx_buf_hash(rx_buf);
+ skb->rxhash = efx_rx_buf_hash(rx_buf);
/* Move past the ethernet header. rx_buf->data still points
* at the ethernet header */
- rx_buf->skb->protocol = eth_type_trans(rx_buf->skb,
- efx->net_dev);
+ skb->protocol = eth_type_trans(skb, efx->net_dev);
- skb_record_rx_queue(rx_buf->skb, channel->channel);
+ skb_record_rx_queue(skb, channel->channel);
}
- if (likely(checksummed || rx_buf->page)) {
+ if (likely(checksummed || rx_buf->is_page)) {
efx_rx_packet_gro(channel, rx_buf, checksummed);
return;
}
/* We now own the SKB */
- skb = rx_buf->skb;
- rx_buf->skb = NULL;
- EFX_BUG_ON_PARANOID(!skb);
+ skb = rx_buf->u.skb;
+ rx_buf->u.skb = NULL;
/* Set the SKB flags */
skb_checksum_none_assert(skb);
--
1.5.4
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
--
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