[PATCH net-next 0/4] i40e: small improvements on XDP path

[PATCH net-next 0/4] i40e: small improvements on XDP path

[Cristian Dumitrescu]

This patchset introduces some small and straightforward improvements
to the Intel i40e driver XDP path. Each improvement is fully described
in its associated patch.

Cristian Dumitrescu (4):
  i40e: remove unnecessary memory writes of the next to clean pointer
  i40e: remove unnecessary cleaned_count updates
  i40e: remove the redundant buffer info updates
  i40: consolidate handling of XDP program actions

 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 149 +++++++++++----------
 1 file changed, 79 insertions(+), 70 deletions(-)

-- 
2.25.1

[PATCH net-next 1/4] i40e: remove unnecessary memory writes of the next to clean pointer

[Cristian Dumitrescu]

For performance reasons, avoid writing the ring next-to-clean pointer
value back to memory on every update, as it is not really necessary.
Instead, simply read it at initialization into a local copy, update
the local copy as necessary and write the local copy back to memory
after the last update.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 30 ++++++++--------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 47eb9c584a12..dc11ecd1a55c 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -261,18 +261,6 @@ static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring,
 	return skb;
 }
 
-/**
- * i40e_inc_ntc: Advance the next_to_clean index
- * @rx_ring: Rx ring
- **/
-static void i40e_inc_ntc(struct i40e_ring *rx_ring)
-{
-	u32 ntc = rx_ring->next_to_clean + 1;
-
-	ntc = (ntc < rx_ring->count) ? ntc : 0;
-	rx_ring->next_to_clean = ntc;
-}
-
 /**
  * i40e_clean_rx_irq_zc - Consumes Rx packets from the hardware ring
  * @rx_ring: Rx ring
@@ -284,6 +272,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 {
 	unsigned int total_rx_bytes = 0, total_rx_packets = 0;
 	u16 cleaned_count = I40E_DESC_UNUSED(rx_ring);
+	u16 next_to_clean = rx_ring->next_to_clean;
+	u16 count_mask = rx_ring->count - 1;
 	unsigned int xdp_res, xdp_xmit = 0;
 	bool failure = false;
 	struct sk_buff *skb;
@@ -294,7 +284,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		unsigned int size;
 		u64 qword;
 
-		rx_desc = I40E_RX_DESC(rx_ring, rx_ring->next_to_clean);
+		rx_desc = I40E_RX_DESC(rx_ring, next_to_clean);
 		qword = le64_to_cpu(rx_desc->wb.qword1.status_error_len);
 
 		/* This memory barrier is needed to keep us from reading
@@ -307,11 +297,11 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 			i40e_clean_programming_status(rx_ring,
 						      rx_desc->raw.qword[0],
 						      qword);
-			bi = i40e_rx_bi(rx_ring, rx_ring->next_to_clean);
+			bi = i40e_rx_bi(rx_ring, next_to_clean);
 			xsk_buff_free(*bi);
 			*bi = NULL;
 			cleaned_count++;
-			i40e_inc_ntc(rx_ring);
+			next_to_clean = (next_to_clean + 1) & count_mask;
 			continue;
 		}
 
@@ -320,7 +310,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		if (!size)
 			break;
 
-		bi = i40e_rx_bi(rx_ring, rx_ring->next_to_clean);
+		bi = i40e_rx_bi(rx_ring, next_to_clean);
 		(*bi)->data_end = (*bi)->data + size;
 		xsk_buff_dma_sync_for_cpu(*bi, rx_ring->xsk_pool);
 
@@ -336,7 +326,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 			total_rx_packets++;
 
 			cleaned_count++;
-			i40e_inc_ntc(rx_ring);
+			next_to_clean = (next_to_clean + 1) & count_mask;
 			continue;
 		}
 
@@ -355,7 +345,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		}
 
 		cleaned_count++;
-		i40e_inc_ntc(rx_ring);
+		next_to_clean = (next_to_clean + 1) & count_mask;
 
 		if (eth_skb_pad(skb))
 			continue;
@@ -367,6 +357,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		napi_gro_receive(&rx_ring->q_vector->napi, skb);
 	}
 
+	rx_ring->next_to_clean = next_to_clean;
+
 	if (cleaned_count >= I40E_RX_BUFFER_WRITE)
 		failure = !i40e_alloc_rx_buffers_zc(rx_ring, cleaned_count);
 
@@ -374,7 +366,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 	i40e_update_rx_stats(rx_ring, total_rx_bytes, total_rx_packets);
 
 	if (xsk_uses_need_wakeup(rx_ring->xsk_pool)) {
-		if (failure || rx_ring->next_to_clean == rx_ring->next_to_use)
+		if (failure || next_to_clean == rx_ring->next_to_use)
 			xsk_set_rx_need_wakeup(rx_ring->xsk_pool);
 		else
 			xsk_clear_rx_need_wakeup(rx_ring->xsk_pool);
-- 
2.25.1

[PATCH net-next 2/4] i40e: remove unnecessary cleaned_count updates

[Cristian Dumitrescu]

For performance reasons, remove the redundant updates of the cleaned_count
variable, as its value can be computed based on the ring next-to-clean
variable, which is consistently udpated.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index dc11ecd1a55c..453ef30d9498 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -300,7 +300,6 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 			bi = i40e_rx_bi(rx_ring, next_to_clean);
 			xsk_buff_free(*bi);
 			*bi = NULL;
-			cleaned_count++;
 			next_to_clean = (next_to_clean + 1) & count_mask;
 			continue;
 		}
@@ -325,7 +324,6 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 			total_rx_bytes += size;
 			total_rx_packets++;
 
-			cleaned_count++;
 			next_to_clean = (next_to_clean + 1) & count_mask;
 			continue;
 		}
@@ -344,7 +342,6 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 			break;
 		}
 
-		cleaned_count++;
 		next_to_clean = (next_to_clean + 1) & count_mask;
 
 		if (eth_skb_pad(skb))
@@ -358,6 +355,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 	}
 
 	rx_ring->next_to_clean = next_to_clean;
+	cleaned_count = (next_to_clean - rx_ring->next_to_use - 1) & count_mask;
 
 	if (cleaned_count >= I40E_RX_BUFFER_WRITE)
 		failure = !i40e_alloc_rx_buffers_zc(rx_ring, cleaned_count);
-- 
2.25.1

[PATCH net-next 3/4] i40e: remove the redundant buffer info updates

[Cristian Dumitrescu]

For performace reasons, remove the redundant buffer info updates
(*bi = NULL). The buffers ready to be cleaned can easily be tracked
based on the ring next-to-clean variable, which is consistently
updated.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 33 +++++++++-------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 453ef30d9498..1167496a2e08 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -280,7 +280,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 
 	while (likely(total_rx_packets < (unsigned int)budget)) {
 		union i40e_rx_desc *rx_desc;
-		struct xdp_buff **bi;
+		struct xdp_buff *bi;
 		unsigned int size;
 		u64 qword;
 
@@ -297,9 +297,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 			i40e_clean_programming_status(rx_ring,
 						      rx_desc->raw.qword[0],
 						      qword);
-			bi = i40e_rx_bi(rx_ring, next_to_clean);
-			xsk_buff_free(*bi);
-			*bi = NULL;
+			bi = *i40e_rx_bi(rx_ring, next_to_clean);
+			xsk_buff_free(bi);
 			next_to_clean = (next_to_clean + 1) & count_mask;
 			continue;
 		}
@@ -309,18 +308,17 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		if (!size)
 			break;
 
-		bi = i40e_rx_bi(rx_ring, next_to_clean);
-		(*bi)->data_end = (*bi)->data + size;
-		xsk_buff_dma_sync_for_cpu(*bi, rx_ring->xsk_pool);
+		bi = *i40e_rx_bi(rx_ring, next_to_clean);
+		bi->data_end = bi->data + size;
+		xsk_buff_dma_sync_for_cpu(bi, rx_ring->xsk_pool);
 
-		xdp_res = i40e_run_xdp_zc(rx_ring, *bi);
+		xdp_res = i40e_run_xdp_zc(rx_ring, bi);
 		if (xdp_res) {
 			if (xdp_res & (I40E_XDP_TX | I40E_XDP_REDIR))
 				xdp_xmit |= xdp_res;
 			else
-				xsk_buff_free(*bi);
+				xsk_buff_free(bi);
 
-			*bi = NULL;
 			total_rx_bytes += size;
 			total_rx_packets++;
 
@@ -335,8 +333,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		 * BIT(I40E_RXD_QW1_ERROR_SHIFT). This is due to that
 		 * SBP is *not* set in PRT_SBPVSI (default not set).
 		 */
-		skb = i40e_construct_skb_zc(rx_ring, *bi);
-		*bi = NULL;
+		skb = i40e_construct_skb_zc(rx_ring, bi);
 		if (!skb) {
 			rx_ring->rx_stats.alloc_buff_failed++;
 			break;
@@ -594,16 +591,14 @@ int i40e_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
 
 void i40e_xsk_clean_rx_ring(struct i40e_ring *rx_ring)
 {
-	u16 i;
-
-	for (i = 0; i < rx_ring->count; i++) {
-		struct xdp_buff *rx_bi = *i40e_rx_bi(rx_ring, i);
+	u16 count_mask = rx_ring->count - 1;
+	u16 ntc = rx_ring->next_to_clean;
+	u16 ntu = rx_ring->next_to_use;
 
-		if (!rx_bi)
-			continue;
+	for ( ; ntc != ntu; ntc = (ntc + 1)  & count_mask) {
+		struct xdp_buff *rx_bi = *i40e_rx_bi(rx_ring, ntc);
 
 		xsk_buff_free(rx_bi);
-		rx_bi = NULL;
 	}
 }
 
-- 
2.25.1

[PATCH net-next 4/4] i40: consolidate handling of XDP program actions

[Cristian Dumitrescu]

Consolidate the actions performed on the packet based on the XDP
program result into a separate function that is easier to read and
maintain. Simplify the i40e_construct_skb_zc function, so that the
input xdp buffer is always freed, regardless of whether the output
skb is successfully created or not. Simplify the behavior of the
i40e_clean_rx_irq_zc function, so that the current packet descriptor
is dropped when function i40_construct_skb_zc returns an error as
opposed to re-processing the same description on the next invocation.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 98 ++++++++++++++--------
 1 file changed, 61 insertions(+), 37 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 1167496a2e08..470b8600adb1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -250,17 +250,70 @@ static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring,
 			       xdp->data_end - xdp->data_hard_start,
 			       GFP_ATOMIC | __GFP_NOWARN);
 	if (unlikely(!skb))
-		return NULL;
+		goto out;
 
 	skb_reserve(skb, xdp->data - xdp->data_hard_start);
 	memcpy(__skb_put(skb, datasize), xdp->data, datasize);
 	if (metasize)
 		skb_metadata_set(skb, metasize);
 
+out:
 	xsk_buff_free(xdp);
 	return skb;
 }
 
+static void i40e_handle_xdp_result_zc(struct i40e_ring *rx_ring,
+				      struct xdp_buff *xdp_buff,
+				      union i40e_rx_desc *rx_desc,
+				      unsigned int *rx_packets,
+				      unsigned int *rx_bytes,
+				      unsigned int size,
+				      unsigned int xdp_res)
+{
+	struct sk_buff *skb;
+
+	*rx_packets = 1;
+	*rx_bytes = size;
+
+	if (likely(xdp_res == I40E_XDP_REDIR) || xdp_res == I40E_XDP_TX)
+		return;
+
+	if (xdp_res == I40E_XDP_CONSUMED) {
+		xsk_buff_free(xdp_buff);
+		return;
+	}
+
+	if (xdp_res == I40E_XDP_PASS) {
+		/* NB! We are not checking for errors using
+		 * i40e_test_staterr with
+		 * BIT(I40E_RXD_QW1_ERROR_SHIFT). This is due to that
+		 * SBP is *not* set in PRT_SBPVSI (default not set).
+		 */
+		skb = i40e_construct_skb_zc(rx_ring, xdp_buff);
+		if (!skb) {
+			rx_ring->rx_stats.alloc_buff_failed++;
+			*rx_packets = 0;
+			*rx_bytes = 0;
+			return;
+		}
+
+		if (eth_skb_pad(skb)) {
+			*rx_packets = 0;
+			*rx_bytes = 0;
+			return;
+		}
+
+		*rx_bytes = skb->len;
+		i40e_process_skb_fields(rx_ring, rx_desc, skb);
+		napi_gro_receive(&rx_ring->q_vector->napi, skb);
+		return;
+	}
+
+	/* Should never get here, as all valid cases have been handled already.
+	 */
+	WARN_ON_ONCE(1);
+}
+
 /**
  * i40e_clean_rx_irq_zc - Consumes Rx packets from the hardware ring
  * @rx_ring: Rx ring
@@ -276,10 +329,11 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 	u16 count_mask = rx_ring->count - 1;
 	unsigned int xdp_res, xdp_xmit = 0;
 	bool failure = false;
-	struct sk_buff *skb;
 
 	while (likely(total_rx_packets < (unsigned int)budget)) {
 		union i40e_rx_desc *rx_desc;
+		unsigned int rx_packets;
+		unsigned int rx_bytes;
 		struct xdp_buff *bi;
 		unsigned int size;
 		u64 qword;
@@ -313,42 +367,12 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
 		xsk_buff_dma_sync_for_cpu(bi, rx_ring->xsk_pool);
 
 		xdp_res = i40e_run_xdp_zc(rx_ring, bi);
-		if (xdp_res) {
-			if (xdp_res & (I40E_XDP_TX | I40E_XDP_REDIR))
-				xdp_xmit |= xdp_res;
-			else
-				xsk_buff_free(bi);
-
-			total_rx_bytes += size;
-			total_rx_packets++;
-
-			next_to_clean = (next_to_clean + 1) & count_mask;
-			continue;
-		}
-
-		/* XDP_PASS path */
-
-		/* NB! We are not checking for errors using
-		 * i40e_test_staterr with
-		 * BIT(I40E_RXD_QW1_ERROR_SHIFT). This is due to that
-		 * SBP is *not* set in PRT_SBPVSI (default not set).
-		 */
-		skb = i40e_construct_skb_zc(rx_ring, bi);
-		if (!skb) {
-			rx_ring->rx_stats.alloc_buff_failed++;
-			break;
-		}
-
+		i40e_handle_xdp_result_zc(rx_ring, bi, rx_desc, &rx_packets,
+					  &rx_bytes, size, xdp_res);
+		total_rx_packets += rx_packets;
+		total_rx_bytes += rx_bytes;
+		xdp_xmit |= xdp_res & (I40E_XDP_TX | I40E_XDP_REDIR);
 		next_to_clean = (next_to_clean + 1) & count_mask;
-
-		if (eth_skb_pad(skb))
-			continue;
-
-		total_rx_bytes += skb->len;
-		total_rx_packets++;
-
-		i40e_process_skb_fields(rx_ring, rx_desc, skb);
-		napi_gro_receive(&rx_ring->q_vector->napi, skb);
 	}
 
 	rx_ring->next_to_clean = next_to_clean;
-- 
2.25.1

Re: [PATCH net-next 0/4] i40e: small improvements on XDP path

[Saeed Mahameed]

On Thu, 2021-01-14 at 14:33 +0000, Cristian Dumitrescu wrote:
> This patchset introduces some small and straightforward improvements
> to the Intel i40e driver XDP path. Each improvement is fully
> described
> in its associated patch.
> 
> Cristian Dumitrescu (4):
>   i40e: remove unnecessary memory writes of the next to clean pointer
>   i40e: remove unnecessary cleaned_count updates
>   i40e: remove the redundant buffer info updates
>   i40: consolidate handling of XDP program actions
> 
>  drivers/net/ethernet/intel/i40e/i40e_xsk.c | 149 +++++++++++------
> ----
>  1 file changed, 79 insertions(+), 70 deletions(-)
> 
FWIW,
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>

Re: [PATCH net-next 0/4] i40e: small improvements on XDP path

[Magnus Karlsson]

On Thu, Jan 14, 2021 at 3:34 PM Cristian Dumitrescu
<cristian.dumitrescu@intel.com> wrote:
>
> This patchset introduces some small and straightforward improvements
> to the Intel i40e driver XDP path. Each improvement is fully described
> in its associated patch.
>
> Cristian Dumitrescu (4):
>   i40e: remove unnecessary memory writes of the next to clean pointer
>   i40e: remove unnecessary cleaned_count updates
>   i40e: remove the redundant buffer info updates
>   i40: consolidate handling of XDP program actions
>
>  drivers/net/ethernet/intel/i40e/i40e_xsk.c | 149 +++++++++++----------
>  1 file changed, 79 insertions(+), 70 deletions(-)
>
> --
> 2.25.1
>

Thank you for these clean ups Cristian!

For the series:

Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>

Re: [PATCH net-next 0/4] i40e: small improvements on XDP path

[Jakub Kicinski]

On Mon, 18 Jan 2021 08:31:23 +0100 Magnus Karlsson wrote:
> On Thu, Jan 14, 2021 at 3:34 PM Cristian Dumitrescu
> <cristian.dumitrescu@intel.com> wrote:
> >
> > This patchset introduces some small and straightforward improvements
> > to the Intel i40e driver XDP path. Each improvement is fully described
> > in its associated patch.
> 
> Thank you for these clean ups Cristian!
> 
> For the series:
> 
> Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>

FWIW since this series is 100% driver code I'm expecting it will 
come downstream via Tony's tree. Please LMK if that's not the case.

Re: [PATCH net-next 0/4] i40e: small improvements on XDP path

[Maciej Fijalkowski]

On Mon, Jan 18, 2021 at 10:32:33AM -0800, Jakub Kicinski wrote:
> On Mon, 18 Jan 2021 08:31:23 +0100 Magnus Karlsson wrote:
> > On Thu, Jan 14, 2021 at 3:34 PM Cristian Dumitrescu
> > <cristian.dumitrescu@intel.com> wrote:
> > >
> > > This patchset introduces some small and straightforward improvements
> > > to the Intel i40e driver XDP path. Each improvement is fully described
> > > in its associated patch.
> > 
> > Thank you for these clean ups Cristian!
> > 
> > For the series:
> > 
> > Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
> 
> FWIW since this series is 100% driver code I'm expecting it will 
> come downstream via Tony's tree. Please LMK if that's not the case.

I just realized that this set got somewhat abandonded. Tony, can you pick
this? I wouldn't be surprised if it wouldn't apply cleanly anymore since
it has been almost 4 months since the initial submission, but let's see...
Otherwise we probably would have to ask Cristian to re-submit directly to
IWL I guess.

Re: [PATCH net-next 0/4] i40e: small improvements on XDP path

[Nguyen, Anthony L]

On Sat, 2021-05-08 at 00:11 +0200, Maciej Fijalkowski wrote:
> On Mon, Jan 18, 2021 at 10:32:33AM -0800, Jakub Kicinski wrote:
> > On Mon, 18 Jan 2021 08:31:23 +0100 Magnus Karlsson wrote:
> > > On Thu, Jan 14, 2021 at 3:34 PM Cristian Dumitrescu
> > > <cristian.dumitrescu@intel.com> wrote:
> > > > 
> > > > This patchset introduces some small and straightforward
> > > > improvements
> > > > to the Intel i40e driver XDP path. Each improvement is fully
> > > > described
> > > > in its associated patch.
> > > 
> > > Thank you for these clean ups Cristian!
> > > 
> > > For the series:
> > > 
> > > Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
> > 
> > FWIW since this series is 100% driver code I'm expecting it will 
> > come downstream via Tony's tree. Please LMK if that's not the case.
> 
> I just realized that this set got somewhat abandonded. Tony, can you
> pick
> this? I wouldn't be surprised if it wouldn't apply cleanly anymore
> since
> it has been almost 4 months since the initial submission, but let's
> see...
> Otherwise we probably would have to ask Cristian to re-submit
> directly to
> IWL I guess.

If I'm not mistaken, these were sent and accepted in this request.

https://lore.kernel.org/netdev/20210209022323.2440775-1-anthony.l.nguyen@intel.com/

Thanks,
Tony