From mboxrd@z Thu Jan 1 00:00:00 1970 From: Samudrala, Sridhar Date: Tue, 23 Jun 2020 18:08:37 -0700 Subject: [Intel-wired-lan] [PATCH net-next v2 1/3] i40e: optimize AF_XDP Tx completion path In-Reply-To: <1592905458-850-2-git-send-email-magnus.karlsson@intel.com> References: <1592905458-850-1-git-send-email-magnus.karlsson@intel.com> <1592905458-850-2-git-send-email-magnus.karlsson@intel.com> Message-ID: <8cf93eaa-9c0d-3b5c-e9e2-1d95dd2fd1d8@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On 6/23/2020 2:44 AM, Magnus Karlsson wrote: > 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 Reviewed-by: Sridhar Samudrala > --- > drivers/net/ethernet/intel/i40e/i40e_txrx.c | 3 +- > drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 + > drivers/net/ethernet/intel/i40e/i40e_xsk.c | 43 +++++++++++++++-------------- > drivers/net/ethernet/intel/i40e/i40e_xsk.h | 3 +- > 4 files changed, 27 insertions(+), 23 deletions(-) > > diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c > index f9555c8..9334abd 100644 > --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c > +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c > @@ -2580,7 +2580,7 @@ int i40e_napi_poll(struct napi_struct *napi, int budget) > */ > i40e_for_each_ring(ring, q_vector->tx) { > bool wd = ring->xsk_umem ? > - i40e_clean_xdp_tx_irq(vsi, ring, budget) : > + i40e_clean_xdp_tx_irq(vsi, ring) : > i40e_clean_tx_irq(vsi, ring, budget); > > if (!wd) { > @@ -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..86635f5 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); > @@ -447,27 +453,25 @@ static void i40e_clean_xdp_tx_buffer(struct i40e_ring *tx_ring, > * > * Returns true if cleanup/tranmission is done. > **/ > -bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, > - struct i40e_ring *tx_ring, int napi_budget) > +bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring) > { > - 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; > + bool xmit_done; > > 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 +479,18 @@ 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; > @@ -494,8 +498,7 @@ bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, > if (xsk_frames) > xsk_umem_complete_tx(umem, xsk_frames); > > - i40e_arm_wb(tx_ring, vsi, budget); > - i40e_update_tx_stats(tx_ring, completed_frames, total_bytes); > + i40e_arm_wb(tx_ring, vsi, completed_frames); > > out_xmit: > if (xsk_umem_uses_need_wakeup(tx_ring->xsk_umem)) > @@ -503,7 +506,7 @@ bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, > > xmit_done = i40e_xmit_zc(tx_ring, budget); > > - return work_done && xmit_done; > + return xmit_done; > } > > /** > diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.h b/drivers/net/ethernet/intel/i40e/i40e_xsk.h > index ea919a7d..c524c14 100644 > --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.h > +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.h > @@ -15,8 +15,7 @@ int i40e_xsk_umem_setup(struct i40e_vsi *vsi, struct xdp_umem *umem, > bool i40e_alloc_rx_buffers_zc(struct i40e_ring *rx_ring, u16 cleaned_count); > int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget); > > -bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, > - struct i40e_ring *tx_ring, int napi_budget); > +bool i40e_clean_xdp_tx_irq(struct i40e_vsi *vsi, struct i40e_ring *tx_ring); > int i40e_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags); > int i40e_alloc_rx_bi_zc(struct i40e_ring *rx_ring); > void i40e_clear_rx_bi_zc(struct i40e_ring *rx_ring); >