[PATCH RFC v1 05/15] ixgbe: add XDP frame size to driver

Jesper Dangaard Brouer
2020-03-17T17:29:55Z

The ixgbe driver uses different memory models depending on PAGE_SIZE at
compile time. For PAGE_SIZE 4K it uses page splitting, meaning for
normal MTU frame size is 2048 bytes (and headroom 192 bytes).
For PAGE_SIZE larger than 4K, driver advance its rx_buffer->page_offset
with the frame size "truesize".

When driver enable XDP it uses build_skb() which provides the necessary
tailroom for XDP-redirect.

When XDP frame size doesn't depend on RX packet size (4K case), then
xdp.frame_sz can be updated once outside the main NAPI loop.

Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
drivers/net/ethernet/intel/ixgbe/ixgbe.h | 17 +++++++++++++++++
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 18 ++++++++++--------
2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 2833e4f041ce..943b643b6ed8 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -417,6 +417,23 @@ static inline unsigned int ixgbe_rx_pg_order(struct ixgbe_ring *ring)
}
#define ixgbe_rx_pg_size(_ring) (PAGE_SIZE << ixgbe_rx_pg_order(_ring))

+static inline unsigned int ixgbe_rx_frame_truesize(struct ixgbe_ring *rx_ring,
+ unsigned int size)
+{
+ unsigned int truesize;
+
+#if (PAGE_SIZE < 8192)
+ truesize = ixgbe_rx_pg_size(rx_ring) / 2; /* Must be power-of-2 */
+#else
+ /* Notice XDP must use build_skb() mode */
+ truesize = ring_uses_build_skb(rx_ring) ?
+ SKB_DATA_ALIGN(IXGBE_SKB_PAD + size) +
+ SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) :
+ SKB_DATA_ALIGN(size);
+#endif
+ return truesize;
+}
+
#define IXGBE_ITR_ADAPTIVE_MIN_INC 2
#define IXGBE_ITR_ADAPTIVE_MIN_USECS 10
#define IXGBE_ITR_ADAPTIVE_MAX_USECS 126
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index ea6834bae04c..f505ed8c9dc1 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -2248,16 +2248,10 @@ static void ixgbe_rx_buffer_flip(struct ixgbe_ring *rx_ring,
struct ixgbe_rx_buffer *rx_buffer,
unsigned int size)
{
+ unsigned int truesize = ixgbe_rx_frame_truesize(rx_ring, size);
#if (PAGE_SIZE < 8192)
- unsigned int truesize = ixgbe_rx_pg_size(rx_ring) / 2;
-
rx_buffer->page_offset ^= truesize;
#else
- unsigned int truesize = ring_uses_build_skb(rx_ring) ?
- SKB_DATA_ALIGN(IXGBE_SKB_PAD + size) +
- SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) :
- SKB_DATA_ALIGN(size);
-
rx_buffer->page_offset += truesize;
#endif
}
@@ -2291,6 +2285,11 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,

xdp.rxq = &rx_ring->xdp_rxq;

+ /* Frame size depend on rx_ring setup when PAGE_SIZE=4K */
+#if (PAGE_SIZE < 8192)
+ xdp.frame_sz = ixgbe_rx_frame_truesize(rx_ring, 0);
+#endif
+
while (likely(total_rx_packets < budget)) {
union ixgbe_adv_rx_desc *rx_desc;
struct ixgbe_rx_buffer *rx_buffer;
@@ -2324,7 +2323,10 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
xdp.data_hard_start = xdp.data -
ixgbe_rx_offset(rx_ring);
xdp.data_end = xdp.data + size;
-
+#if (PAGE_SIZE > 4096)
+ /* At larger PAGE_SIZE, frame_sz depend on size */
+ xdp.frame_sz = ixgbe_rx_frame_truesize(rx_ring, size);
+#endif
skb = ixgbe_run_xdp(adapter, rx_ring, &xdp);
}