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Message-Id: <1592832083-23249-2-git-send-email-magnus.karlsson@intel.com>
Date: Mon, 22 Jun 2020 15:21:22 +0200
From: Magnus Karlsson <magnus.karlsson@...el.com>
To: magnus.karlsson@...el.com, bjorn.topel@...el.com,
intel-wired-lan@...ts.osuosl.org, jeffrey.t.kirsher@...el.com
Cc: maciej.fijalkowski@...el.com, maciejromanfijalkowski@...il.com,
netdev@...r.kernel.org
Subject: [PATCH net-next 1/2] i40e: optimize AF_XDP Tx completion path
Improve the performance of the AF_XDP zero-copy Tx completion
path. When there are no XDP buffers being sent using XDP_TX or
XDP_REDIRECT, we do not have go through the SW ring to clean up any
entries since the AF_XDP path does not use these. In these cases, just
fast forward the next-to-use counter and skip going through the SW
ring. The limit on the maximum number of entries to complete is also
removed since the algorithm is now O(1). To simplify the code path, the
maximum number of entries to complete for the XDP path is therefore
also increased from 256 to 512 (the default number of Tx HW
descriptors). This should be fine since the completion in the XDP path
is faster than in the SKB path that has 256 as the maximum number.
This patch provides around 4% throughput improvement for the l2fwd
application in xdpsock on my machine.
Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
---
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 1 +
drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 +
drivers/net/ethernet/intel/i40e/i40e_xsk.c | 34 ++++++++++++++++-------------
3 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index f9555c8..0ce9d1e 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -3538,6 +3538,7 @@ static int i40e_xmit_xdp_ring(struct xdp_frame *xdpf,
*/
smp_wmb();
+ xdp_ring->xdp_tx_active++;
i++;
if (i == xdp_ring->count)
i = 0;
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index 5c25597..c16fcd9 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -371,6 +371,7 @@ struct i40e_ring {
/* used in interrupt processing */
u16 next_to_use;
u16 next_to_clean;
+ u16 xdp_tx_active;
u8 atr_sample_rate;
u8 atr_count;
diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 7276580..c8cd6a6 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -378,6 +378,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
**/
static bool i40e_xmit_zc(struct i40e_ring *xdp_ring, unsigned int budget)
{
+ unsigned int sent_frames = 0, total_bytes = 0;
struct i40e_tx_desc *tx_desc = NULL;
struct i40e_tx_buffer *tx_bi;
bool work_done = true;
@@ -408,6 +409,9 @@ static bool i40e_xmit_zc(struct i40e_ring *xdp_ring, unsigned int budget)
| I40E_TX_DESC_CMD_EOP,
0, desc.len, 0);
+ sent_frames++;
+ total_bytes += tx_bi->bytecount;
+
xdp_ring->next_to_use++;
if (xdp_ring->next_to_use == xdp_ring->count)
xdp_ring->next_to_use = 0;
@@ -420,6 +424,7 @@ static bool i40e_xmit_zc(struct i40e_ring *xdp_ring, unsigned int budget)
i40e_xdp_ring_update_tail(xdp_ring);
xsk_umem_consume_tx_done(xdp_ring->xsk_umem);
+ i40e_update_tx_stats(xdp_ring, sent_frames, total_bytes);
}
return !!budget && work_done;
@@ -434,6 +439,7 @@ static void i40e_clean_xdp_tx_buffer(struct i40e_ring *tx_ring,
struct i40e_tx_buffer *tx_bi)
{
xdp_return_frame(tx_bi->xdpf);
+ tx_ring->xdp_tx_active--;
dma_unmap_single(tx_ring->dev,
dma_unmap_addr(tx_bi, dma),
dma_unmap_len(tx_bi, len), DMA_TO_DEVICE);
@@ -450,24 +456,23 @@ static void i40e_clean_xdp_tx_buffer(struct i40e_ring *tx_ring,
bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi,
struct i40e_ring *tx_ring, int napi_budget)
{
- unsigned int ntc, total_bytes = 0, budget = vsi->work_limit;
- u32 i, completed_frames, frames_ready, xsk_frames = 0;
+ unsigned int ntc, budget = vsi->work_limit;
struct xdp_umem *umem = tx_ring->xsk_umem;
+ u32 i, completed_frames, xsk_frames = 0;
u32 head_idx = i40e_get_head(tx_ring);
bool work_done = true, xmit_done;
struct i40e_tx_buffer *tx_bi;
if (head_idx < tx_ring->next_to_clean)
head_idx += tx_ring->count;
- frames_ready = head_idx - tx_ring->next_to_clean;
+ completed_frames = head_idx - tx_ring->next_to_clean;
- if (frames_ready == 0) {
+ if (completed_frames == 0)
goto out_xmit;
- } else if (frames_ready > budget) {
- completed_frames = budget;
- work_done = false;
- } else {
- completed_frames = frames_ready;
+
+ if (likely(!tx_ring->xdp_tx_active)) {
+ xsk_frames = completed_frames;
+ goto skip;
}
ntc = tx_ring->next_to_clean;
@@ -475,18 +480,18 @@ bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi,
for (i = 0; i < completed_frames; i++) {
tx_bi = &tx_ring->tx_bi[ntc];
- if (tx_bi->xdpf)
+ if (tx_bi->xdpf) {
i40e_clean_xdp_tx_buffer(tx_ring, tx_bi);
- else
+ tx_bi->xdpf = NULL;
+ } else {
xsk_frames++;
-
- tx_bi->xdpf = NULL;
- total_bytes += tx_bi->bytecount;
+ }
if (++ntc >= tx_ring->count)
ntc = 0;
}
+skip:
tx_ring->next_to_clean += completed_frames;
if (unlikely(tx_ring->next_to_clean >= tx_ring->count))
tx_ring->next_to_clean -= tx_ring->count;
@@ -495,7 +500,6 @@ bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi,
xsk_umem_complete_tx(umem, xsk_frames);
i40e_arm_wb(tx_ring, vsi, budget);
- i40e_update_tx_stats(tx_ring, completed_frames, total_bytes);
out_xmit:
if (xsk_umem_uses_need_wakeup(tx_ring->xsk_umem))
--
2.7.4
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