[Intel-wired-lan] [RFC PATCH 09/20] igb: Break out Rx buffer page management
Alexander Duyck
alexander.duyck at gmail.com
Mon Dec 19 20:11:34 UTC 2016
From: Alexander Duyck <alexander.h.duyck at intel.com>
At this point we have 2 to 3 paths that can be taken depending on what Rx
modes are enabled. In order to better support that and improve the
maintainability I am breaking out the common bits from those paths and
making them into their own functions.
Signed-off-by: Alexander Duyck <alexander.h.duyck at intel.com>
---
drivers/net/ethernet/intel/igb/igb_main.c | 227 +++++++++++++++--------------
1 file changed, 115 insertions(+), 112 deletions(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index ddc2c2788959..cea252fc7582 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -6868,11 +6868,10 @@ static inline bool igb_page_is_reserved(struct page *page)
return (page_to_nid(page) != numa_mem_id()) || page_is_pfmemalloc(page);
}
-static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer,
- struct page *page,
- const unsigned int truesize)
+static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer)
{
- unsigned int pagecnt_bias = rx_buffer->pagecnt_bias--;
+ unsigned int pagecnt_bias = rx_buffer->pagecnt_bias;
+ struct page *page = rx_buffer->page;
/* avoid re-using remote pages */
if (unlikely(igb_page_is_reserved(page)))
@@ -6880,14 +6879,9 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer,
#if (PAGE_SIZE < 8192)
/* if we are only owner of page we can reuse it */
- if (unlikely(page_ref_count(page) != pagecnt_bias))
+ if (unlikely((page_ref_count(page) - pagecnt_bias) > 1))
return false;
-
- /* flip page offset to other buffer */
- rx_buffer->page_offset ^= truesize;
#else
- /* move offset up to the next cache line */
- rx_buffer->page_offset += truesize;
#define IGB_LAST_OFFSET \
(SKB_WITH_OVERHEAD(PAGE_SIZE) - IGB_RXBUFFER_2048)
@@ -6899,7 +6893,7 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer,
* the pagecnt_bias and page count so that we fully restock the
* number of references the driver holds.
*/
- if (unlikely(pagecnt_bias == 1)) {
+ if (unlikely(!pagecnt_bias)) {
page_ref_add(page, USHRT_MAX);
rx_buffer->pagecnt_bias = USHRT_MAX;
}
@@ -6911,26 +6905,16 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer,
* igb_add_rx_frag - Add contents of Rx buffer to sk_buff
* @rx_ring: rx descriptor ring to transact packets on
* @rx_buffer: buffer containing page to add
- * @rx_desc: descriptor containing length of buffer written by hardware
* @skb: sk_buff to place the data into
+ * @size: size of buffer to be added
*
* This function will add the data contained in rx_buffer->page to the skb.
- * This is done either through a direct copy if the data in the buffer is
- * less than the skb header size, otherwise it will just attach the page as
- * a frag to the skb.
- *
- * The function will then update the page offset if necessary and return
- * true if the buffer can be reused by the adapter.
**/
-static bool igb_add_rx_frag(struct igb_ring *rx_ring,
+static void igb_add_rx_frag(struct igb_ring *rx_ring,
struct igb_rx_buffer *rx_buffer,
- unsigned int size,
- union e1000_adv_rx_desc *rx_desc,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ unsigned int size)
{
- struct page *page = rx_buffer->page;
- unsigned char *va = page_address(page) + rx_buffer->page_offset;
- unsigned int pull_len;
#if (PAGE_SIZE < 8192)
unsigned int truesize = igb_rx_pg_size(rx_ring) / 2;
#else
@@ -6938,9 +6922,39 @@ static bool igb_add_rx_frag(struct igb_ring *rx_ring,
SKB_DATA_ALIGN(IGB_SKB_PAD + size) :
SKB_DATA_ALIGN(size);
#endif
+ skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_buffer->page,
+ rx_buffer->page_offset, size, truesize);
+#if (PAGE_SIZE < 8192)
+ rx_buffer->page_offset ^= truesize;
+#else
+ rx_buffer->page_offset += truesize;
+#endif
+}
+
+static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
+ struct igb_rx_buffer *rx_buffer,
+ union e1000_adv_rx_desc *rx_desc,
+ unsigned int size)
+{
+ void *va = page_address(rx_buffer->page) + rx_buffer->page_offset;
+#if (PAGE_SIZE < 8192)
+ unsigned int truesize = igb_rx_pg_size(rx_ring) / 2;
+#else
+ unsigned int truesize = SKB_DATA_ALIGN(size);
+#endif
+ unsigned int headlen;
+ struct sk_buff *skb;
- if (unlikely(skb_is_nonlinear(skb)))
- goto add_tail_frag;
+ /* prefetch first cache line of first page */
+ prefetch(va);
+#if L1_CACHE_BYTES < 128
+ prefetch(va + L1_CACHE_BYTES);
+#endif
+
+ /* allocate a skb to store the frags */
+ skb = napi_alloc_skb(&rx_ring->q_vector->napi, IGB_RX_HDR_LEN);
+ if (unlikely(!skb))
+ return NULL;
if (unlikely(igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP))) {
igb_ptp_rx_pktstamp(rx_ring->q_vector, va, skb);
@@ -6948,95 +6962,31 @@ static bool igb_add_rx_frag(struct igb_ring *rx_ring,
size -= IGB_TS_HDR_LEN;
}
- if (likely(size <= IGB_RX_HDR_LEN)) {
- memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long)));
-
- /* page is not reserved, we can reuse buffer as-is */
- if (likely(!igb_page_is_reserved(page)))
- return true;
-
- /* this page cannot be reused so discard it */
- return false;
- }
-
- /* we need the header to contain the greater of either ETH_HLEN or
- * 60 bytes if the skb->len is less than 60 for skb_pad.
- */
- pull_len = eth_get_headlen(va, IGB_RX_HDR_LEN);
+ /* Determine available headroom for copy */
+ headlen = size;
+ if (headlen > IGB_RX_HDR_LEN)
+ headlen = eth_get_headlen(va, IGB_RX_HDR_LEN);
+ else
+ headlen = size;
/* align pull length to size of long to optimize memcpy performance */
- memcpy(__skb_put(skb, pull_len), va, ALIGN(pull_len, sizeof(long)));
+ memcpy(__skb_put(skb, headlen), va, ALIGN(headlen, sizeof(long)));
/* update all of the pointers */
- va += pull_len;
- size -= pull_len;
-
-add_tail_frag:
- skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
- va - page_address(page), size, truesize);
-
- return igb_can_reuse_rx_page(rx_buffer, page, truesize);
-}
-
-static struct sk_buff *igb_fetch_rx_buffer(struct igb_ring *rx_ring,
- union e1000_adv_rx_desc *rx_desc,
- struct sk_buff *skb)
-{
- unsigned int size = le16_to_cpu(rx_desc->wb.upper.length);
- struct igb_rx_buffer *rx_buffer;
- struct page *page;
-
- rx_buffer = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
- page = rx_buffer->page;
- prefetchw(page);
-
- /* we are reusing so sync this buffer for CPU use */
- dma_sync_single_range_for_cpu(rx_ring->dev,
- rx_buffer->dma,
- rx_buffer->page_offset,
- size,
- DMA_FROM_DEVICE);
-
- if (likely(!skb)) {
- void *va = page_address(page) + rx_buffer->page_offset;
-
- /* prefetch first cache line of first page */
- prefetch(va);
-#if L1_CACHE_BYTES < 128
- prefetch(va + L1_CACHE_BYTES);
+ size -= headlen;
+ if (size) {
+ skb_add_rx_frag(skb, 0, rx_buffer->page,
+ (va + headlen) - page_address(rx_buffer->page),
+ size, truesize);
+#if (PAGE_SIZE < 8192)
+ rx_buffer->page_offset ^= truesize;
+#else
+ rx_buffer->page_offset += truesize;
#endif
-
- /* allocate a skb to store the frags */
- skb = napi_alloc_skb(&rx_ring->q_vector->napi, IGB_RX_HDR_LEN);
- if (unlikely(!skb)) {
- rx_ring->rx_stats.alloc_failed++;
- return NULL;
- }
-
- /* we will be copying header into skb->data in
- * pskb_may_pull so it is in our interest to prefetch
- * it now to avoid a possible cache miss
- */
- prefetchw(skb->data);
- }
-
- /* pull page into skb */
- if (igb_add_rx_frag(rx_ring, rx_buffer, size, rx_desc, skb)) {
- /* hand second half of page back to the ring */
- igb_reuse_rx_page(rx_ring, rx_buffer);
} else {
- /* We are not reusing the buffer so unmap it and free
- * any references we are holding to it
- */
- dma_unmap_page_attrs(rx_ring->dev, rx_buffer->dma,
- igb_rx_pg_size(rx_ring), DMA_FROM_DEVICE,
- IGB_RX_DMA_ATTR);
- __page_frag_cache_drain(page, rx_buffer->pagecnt_bias);
+ rx_buffer->pagecnt_bias++;
}
- /* clear contents of rx_buffer */
- rx_buffer->page = NULL;
-
return skb;
}
@@ -7194,6 +7144,47 @@ static void igb_process_skb_fields(struct igb_ring *rx_ring,
skb->protocol = eth_type_trans(skb, rx_ring->netdev);
}
+static struct igb_rx_buffer *igb_get_rx_buffer(struct igb_ring *rx_ring,
+ const unsigned int size)
+{
+ struct igb_rx_buffer *rx_buffer;
+
+ rx_buffer = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
+ prefetchw(rx_buffer->page);
+
+ /* we are reusing so sync this buffer for CPU use */
+ dma_sync_single_range_for_cpu(rx_ring->dev,
+ rx_buffer->dma,
+ rx_buffer->page_offset,
+ size,
+ DMA_FROM_DEVICE);
+
+ rx_buffer->pagecnt_bias--;
+
+ return rx_buffer;
+}
+
+static void igb_put_rx_buffer(struct igb_ring *rx_ring,
+ struct igb_rx_buffer *rx_buffer)
+{
+ if (igb_can_reuse_rx_page(rx_buffer)) {
+ /* hand second half of page back to the ring */
+ igb_reuse_rx_page(rx_ring, rx_buffer);
+ } else {
+ /* We are not reusing the buffer so unmap it and free
+ * any references we are holding to it
+ */
+ dma_unmap_page_attrs(rx_ring->dev, rx_buffer->dma,
+ igb_rx_pg_size(rx_ring), DMA_FROM_DEVICE,
+ IGB_RX_DMA_ATTR);
+ __page_frag_cache_drain(rx_buffer->page,
+ rx_buffer->pagecnt_bias);
+ }
+
+ /* clear contents of rx_buffer */
+ rx_buffer->page = NULL;
+}
+
static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
{
struct igb_ring *rx_ring = q_vector->rx.ring;
@@ -7203,6 +7194,8 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
while (likely(total_packets < budget)) {
union e1000_adv_rx_desc *rx_desc;
+ struct igb_rx_buffer *rx_buffer;
+ unsigned int size;
/* return some buffers to hardware, one at a time is too slow */
if (cleaned_count >= IGB_RX_BUFFER_WRITE) {
@@ -7211,8 +7204,8 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
}
rx_desc = IGB_RX_DESC(rx_ring, rx_ring->next_to_clean);
-
- if (!rx_desc->wb.upper.length)
+ size = le16_to_cpu(rx_desc->wb.upper.length);
+ if (!size)
break;
/* This memory barrier is needed to keep us from reading
@@ -7221,13 +7214,23 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
*/
dma_rmb();
+ rx_buffer = igb_get_rx_buffer(rx_ring, size);
+
/* retrieve a buffer from the ring */
- skb = igb_fetch_rx_buffer(rx_ring, rx_desc, skb);
+ if (skb)
+ igb_add_rx_frag(rx_ring, rx_buffer, skb, size);
+ else
+ skb = igb_construct_skb(rx_ring, rx_buffer,
+ rx_desc, size);
/* exit if we failed to retrieve a buffer */
- if (!skb)
+ if (!skb) {
+ rx_ring->rx_stats.alloc_failed++;
+ rx_buffer->pagecnt_bias++;
break;
+ }
+ igb_put_rx_buffer(rx_ring, rx_buffer);
cleaned_count++;
/* fetch next buffer in frame if non-eop */
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