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Date: Fri, 21 Jan 2022 14:17:42 +0100
From: Alexander Lobakin <alexandr.lobakin@...el.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc: Alexander Lobakin <alexandr.lobakin@...el.com>,
bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
netdev@...r.kernel.org, magnus.karlsson@...el.com
Subject: Re: [PATCH bpf-next v3 6/7] ice: xsk: improve AF_XDP ZC Tx and use batching API
From: Alexander Lobakin <alexandr.lobakin@...el.com>
Date: Fri, 21 Jan 2022 13:54:47 +0100
> From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
> Date: Fri, 21 Jan 2022 13:00:10 +0100
>
> > Apply the logic that was done for regular XDP from commit 9610bd988df9
> > ("ice: optimize XDP_TX workloads") to the ZC side of the driver. On top
> > of that, introduce batching to Tx that is inspired by i40e's
> > implementation with adjustments to the cleaning logic - take into the
> > account NAPI budget in ice_clean_xdp_irq_zc().
> >
> > Separating the stats structs onto separate cache lines seemed to improve
> > the performance.
> >
> > Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
> > ---
> > drivers/net/ethernet/intel/ice/ice_txrx.c | 2 +-
> > drivers/net/ethernet/intel/ice/ice_txrx.h | 2 +-
> > drivers/net/ethernet/intel/ice/ice_xsk.c | 256 ++++++++++++++--------
> > drivers/net/ethernet/intel/ice/ice_xsk.h | 27 ++-
> > 4 files changed, 186 insertions(+), 101 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
> > index bfb9158b10a4..7ab8c700c884 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_txrx.c
> > +++ b/drivers/net/ethernet/intel/ice/ice_txrx.c
> > @@ -1463,7 +1463,7 @@ int ice_napi_poll(struct napi_struct *napi, int budget)
> > bool wd;
> >
> > if (tx_ring->xsk_pool)
> > - wd = ice_clean_tx_irq_zc(tx_ring, budget);
> > + wd = ice_xmit_zc(tx_ring, ICE_DESC_UNUSED(tx_ring), budget);
> > else if (ice_ring_is_xdp(tx_ring))
> > wd = true;
> > else
> > diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.h b/drivers/net/ethernet/intel/ice/ice_txrx.h
> > index 09c8ad2f7403..191f9b8c50ee 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_txrx.h
> > +++ b/drivers/net/ethernet/intel/ice/ice_txrx.h
> > @@ -322,9 +322,9 @@ struct ice_tx_ring {
> > u16 count; /* Number of descriptors */
> > u16 q_index; /* Queue number of ring */
> > /* stats structs */
> > + struct ice_txq_stats tx_stats;
> > struct ice_q_stats stats;
> > struct u64_stats_sync syncp;
> > - struct ice_txq_stats tx_stats;
> >
> > /* CL3 - 3rd cacheline starts here */
> > struct rcu_head rcu; /* to avoid race on free */
> > diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
> > index 0463fc594d08..4b6e54f75af6 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_xsk.c
> > +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
> > @@ -671,134 +671,208 @@ int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget)
> > }
> >
> > /**
> > - * ice_xmit_zc - Completes AF_XDP entries, and cleans XDP entries
> > + * ice_clean_xdp_tx_buf - Free and unmap XDP Tx buffer
> > * @xdp_ring: XDP Tx ring
> > - * @budget: max number of frames to xmit
> > - *
> > - * Returns true if cleanup/transmission is done.
> > + * @tx_buf: Tx buffer to clean
> > */
> > -static bool ice_xmit_zc(struct ice_tx_ring *xdp_ring, int budget)
> > +static void
> > +ice_clean_xdp_tx_buf(struct ice_tx_ring *xdp_ring, struct ice_tx_buf *tx_buf)
> > {
> > - struct ice_tx_desc *tx_desc = NULL;
> > - bool work_done = true;
> > - struct xdp_desc desc;
> > - dma_addr_t dma;
> > -
> > - while (likely(budget-- > 0)) {
> > - struct ice_tx_buf *tx_buf;
> > -
> > - if (unlikely(!ICE_DESC_UNUSED(xdp_ring))) {
> > - xdp_ring->tx_stats.tx_busy++;
> > - work_done = false;
> > - break;
> > - }
> > + xdp_return_frame((struct xdp_frame *)tx_buf->raw_buf);
> > + dma_unmap_single(xdp_ring->dev, dma_unmap_addr(tx_buf, dma),
> > + dma_unmap_len(tx_buf, len), DMA_TO_DEVICE);
> > + dma_unmap_len_set(tx_buf, len, 0);
> > +}
> >
> > - tx_buf = &xdp_ring->tx_buf[xdp_ring->next_to_use];
> > +/**
> > + * ice_clean_xdp_irq_zc - Reclaim resources after transmit completes on XDP ring
> > + * @xdp_ring: XDP ring to clean
> > + * @napi_budget: amount of descriptors that NAPI allows us to clean
> > + *
> > + * Returns count of cleaned descriptors
> > + */
> > +static u16 ice_clean_xdp_irq_zc(struct ice_tx_ring *xdp_ring, int napi_budget)
> > +{
> > + u16 tx_thresh = xdp_ring->tx_thresh;
> > + int budget = napi_budget / tx_thresh;
> > + u16 ntc = xdp_ring->next_to_clean;
> > + struct ice_tx_desc *next_dd_desc;
>
> @next_dd_desc is used only inside the `do { } while`, can be moved
> there the reduce the scope.
>
> > + u16 next_dd = xdp_ring->next_dd;
> > + u16 desc_cnt = xdp_ring->count;
> > + struct ice_tx_buf *tx_buf;
> > + u16 cleared_dds = 0;
> > + u32 xsk_frames = 0;
> > + u16 i;
>
> Same with these 5, from @desc_cnt to @i.
>
> >
> > - if (!xsk_tx_peek_desc(xdp_ring->xsk_pool, &desc))
> > + do {
> > + next_dd_desc = ICE_TX_DESC(xdp_ring, next_dd);
> > + if (!(next_dd_desc->cmd_type_offset_bsz &
> > + cpu_to_le64(ICE_TX_DESC_DTYPE_DESC_DONE)))
> > break;
> >
> > - dma = xsk_buff_raw_get_dma(xdp_ring->xsk_pool, desc.addr);
> > - xsk_buff_raw_dma_sync_for_device(xdp_ring->xsk_pool, dma,
> > - desc.len);
> > + cleared_dds++;
> > + xsk_frames = 0;
> >
> > - tx_buf->bytecount = desc.len;
> > + for (i = 0; i < tx_thresh; i++) {
> > + tx_buf = &xdp_ring->tx_buf[ntc];
> >
> > - tx_desc = ICE_TX_DESC(xdp_ring, xdp_ring->next_to_use);
> > - tx_desc->buf_addr = cpu_to_le64(dma);
> > - tx_desc->cmd_type_offset_bsz =
> > - ice_build_ctob(ICE_TXD_LAST_DESC_CMD, 0, desc.len, 0);
> > + if (tx_buf->raw_buf) {
> > + ice_clean_xdp_tx_buf(xdp_ring, tx_buf);
> > + tx_buf->raw_buf = NULL;
> > + } else {
> > + xsk_frames++;
> > + }
> >
> > - xdp_ring->next_to_use++;
> > - if (xdp_ring->next_to_use == xdp_ring->count)
> > - xdp_ring->next_to_use = 0;
> > - }
> > + ntc++;
> > + if (ntc >= xdp_ring->count)
> > + ntc = 0;
> > + }
> > + if (xsk_frames)
> > + xsk_tx_completed(xdp_ring->xsk_pool, xsk_frames);
> > + next_dd_desc->cmd_type_offset_bsz = 0;
> > + next_dd = next_dd + tx_thresh;
> > + if (next_dd >= desc_cnt)
> > + next_dd = tx_thresh - 1;
> > + } while (budget--);
> >
> > - if (tx_desc) {
> > - ice_xdp_ring_update_tail(xdp_ring);
> > - xsk_tx_release(xdp_ring->xsk_pool);
> > - }
> > + xdp_ring->next_to_clean = ntc;
> > + xdp_ring->next_dd = next_dd;
> >
> > - return budget > 0 && work_done;
> > + return cleared_dds * tx_thresh;
> > }
> >
> > /**
> > - * ice_clean_xdp_tx_buf - Free and unmap XDP Tx buffer
> > - * @xdp_ring: XDP Tx ring
> > - * @tx_buf: Tx buffer to clean
> > + * ice_xmit_pkt - produce a single HW Tx descriptor out of AF_XDP descriptor
> > + * @xdp_ring: XDP ring to produce the HW Tx descriptor on
> > + * @desc: AF_XDP descriptor to pull the DMA address and length from
> > + * @total_bytes: bytes accumulator that will be used for stats update
> > */
> > -static void
> > -ice_clean_xdp_tx_buf(struct ice_tx_ring *xdp_ring, struct ice_tx_buf *tx_buf)
> > +static void ice_xmit_pkt(struct ice_tx_ring *xdp_ring, struct xdp_desc *desc,
> > + unsigned int *total_bytes)
> > {
> > - xdp_return_frame((struct xdp_frame *)tx_buf->raw_buf);
> > - dma_unmap_single(xdp_ring->dev, dma_unmap_addr(tx_buf, dma),
> > - dma_unmap_len(tx_buf, len), DMA_TO_DEVICE);
> > - dma_unmap_len_set(tx_buf, len, 0);
> > + struct ice_tx_desc *tx_desc;
> > + dma_addr_t dma;
> > +
> > + dma = xsk_buff_raw_get_dma(xdp_ring->xsk_pool, desc->addr);
> > + xsk_buff_raw_dma_sync_for_device(xdp_ring->xsk_pool, dma, desc->len);
> > +
> > + tx_desc = ICE_TX_DESC(xdp_ring, xdp_ring->next_to_use++);
> > + tx_desc->buf_addr = cpu_to_le64(dma);
> > + tx_desc->cmd_type_offset_bsz = ice_build_ctob(ICE_TX_DESC_CMD_EOP,
> > + 0, desc->len, 0);
> > +
> > + *total_bytes += desc->len;
> > }
> >
> > /**
> > - * ice_clean_tx_irq_zc - Completes AF_XDP entries, and cleans XDP entries
> > - * @xdp_ring: XDP Tx ring
> > - * @budget: NAPI budget
> > - *
> > - * Returns true if cleanup/tranmission is done.
> > + * ice_xmit_pkt_batch - produce a batch of HW Tx descriptors out of AF_XDP descriptors
> > + * @xdp_ring: XDP ring to produce the HW Tx descriptors on
> > + * @descs: AF_XDP descriptors to pull the DMA addresses and lengths from
> > + * @total_bytes: bytes accumulator that will be used for stats update
> > */
> > -bool ice_clean_tx_irq_zc(struct ice_tx_ring *xdp_ring, int budget)
> > +static void ice_xmit_pkt_batch(struct ice_tx_ring *xdp_ring, struct xdp_desc *descs,
> > + unsigned int *total_bytes)
> > {
> > - int total_packets = 0, total_bytes = 0;
> > - s16 ntc = xdp_ring->next_to_clean;
> > + u16 tx_thresh = xdp_ring->tx_thresh;
> > + u16 ntu = xdp_ring->next_to_use;
> > struct ice_tx_desc *tx_desc;
> > - struct ice_tx_buf *tx_buf;
> > - u32 xsk_frames = 0;
> > - bool xmit_done;
> > + dma_addr_t dma;
>
> Same with @dma here.
>
> > + u32 i;
> >
> > - tx_desc = ICE_TX_DESC(xdp_ring, ntc);
> > - tx_buf = &xdp_ring->tx_buf[ntc];
> > - ntc -= xdp_ring->count;
> > + loop_unrolled_for(i = 0; i < PKTS_PER_BATCH; i++) {
> > + dma = xsk_buff_raw_get_dma(xdp_ring->xsk_pool, descs[i].addr);
> > + xsk_buff_raw_dma_sync_for_device(xdp_ring->xsk_pool, dma, descs[i].len);
> >
> > - do {
> > - if (!(tx_desc->cmd_type_offset_bsz &
> > - cpu_to_le64(ICE_TX_DESC_DTYPE_DESC_DONE)))
> > - break;
> > + tx_desc = ICE_TX_DESC(xdp_ring, ntu++);
> > + tx_desc->buf_addr = cpu_to_le64(dma);
> > + tx_desc->cmd_type_offset_bsz = ice_build_ctob(ICE_TX_DESC_CMD_EOP,
> > + 0, descs[i].len, 0);
> >
> > - total_bytes += tx_buf->bytecount;
> > - total_packets++;
> > + *total_bytes += descs[i].len;
> > + }
> >
> > - if (tx_buf->raw_buf) {
> > - ice_clean_xdp_tx_buf(xdp_ring, tx_buf);
> > - tx_buf->raw_buf = NULL;
> > - } else {
> > - xsk_frames++;
> > - }
> > + xdp_ring->next_to_use = ntu;
> >
> > - tx_desc->cmd_type_offset_bsz = 0;
> > - tx_buf++;
> > - tx_desc++;
> > - ntc++;
> > + if (xdp_ring->next_to_use > xdp_ring->next_rs) {
> > + tx_desc = ICE_TX_DESC(xdp_ring, xdp_ring->next_rs);
> > + tx_desc->cmd_type_offset_bsz |=
> > + cpu_to_le64(ICE_TX_DESC_CMD_RS << ICE_TXD_QW1_CMD_S);
> > + xdp_ring->next_rs += tx_thresh;
> > + }
> > +}
> >
> > - if (unlikely(!ntc)) {
> > - ntc -= xdp_ring->count;
> > - tx_buf = xdp_ring->tx_buf;
> > - tx_desc = ICE_TX_DESC(xdp_ring, 0);
> > - }
> > +/**
> > + * ice_fill_tx_hw_ring - produce the number of Tx descriptors onto ring
> > + * @xdp_ring: XDP ring to produce the HW Tx descriptors on
> > + * @descs: AF_XDP descriptors to pull the DMA addresses and lengths from
> > + * @nb_pkts: count of packets to be send
> > + * @total_bytes: bytes accumulator that will be used for stats update
> > + */
> > +static void ice_fill_tx_hw_ring(struct ice_tx_ring *xdp_ring, struct xdp_desc *descs,
> > + u32 nb_pkts, unsigned int *total_bytes)
> > +{
> > + u16 tx_thresh = xdp_ring->tx_thresh;
> > + struct ice_tx_desc *tx_desc;
>
> And @tx_desc as well.
>
> > + u32 batched, leftover, i;
> > +
> > + batched = nb_pkts & ~(PKTS_PER_BATCH - 1);
> > + leftover = nb_pkts & (PKTS_PER_BATCH - 1);
> > + for (i = 0; i < batched; i += PKTS_PER_BATCH)
> > + ice_xmit_pkt_batch(xdp_ring, &descs[i], total_bytes);
> > + for (i = batched; i < batched + leftover; i++)
Breh, I overlooked that. @i will equal @batched after exiting the
first loop, so the assignment here is redundant (probably harmless
tho if the compilers are smart enough).
> > + ice_xmit_pkt(xdp_ring, &descs[i], total_bytes);
> > +
> > + if (xdp_ring->next_to_use > xdp_ring->next_rs) {
> > + tx_desc = ICE_TX_DESC(xdp_ring, xdp_ring->next_rs);
> > + tx_desc->cmd_type_offset_bsz |=
> > + cpu_to_le64(ICE_TX_DESC_CMD_RS << ICE_TXD_QW1_CMD_S);
> > + xdp_ring->next_rs += tx_thresh;
> > + }
> > +}
> >
> > - prefetch(tx_desc);
> > +/**
> > + * ice_xmit_zc - take entries from XSK Tx ring and place them onto HW Tx ring
> > + * @xdp_ring: XDP ring to produce the HW Tx descriptors on
> > + * @budget: number of free descriptors on HW Tx ring that can be used
> > + * @napi_budget: amount of descriptors that NAPI allows us to clean
> > + *
> > + * Returns true if there is no more work that needs to be done, false otherwise
> > + */
> > +bool ice_xmit_zc(struct ice_tx_ring *xdp_ring, u32 budget, int napi_budget)
> > +{
> > + struct xdp_desc *descs = xdp_ring->xsk_pool->tx_descs;
> > + u16 tx_thresh = xdp_ring->tx_thresh;
> > + u32 nb_pkts, nb_processed = 0;
> > + unsigned int total_bytes = 0;
> > + struct ice_tx_desc *tx_desc;
>
> And this @tx_desc.
>
> >
> > - } while (likely(--budget));
> > + if (budget < tx_thresh)
> > + budget += ice_clean_xdp_irq_zc(xdp_ring, napi_budget);
> > +
> > + nb_pkts = xsk_tx_peek_release_desc_batch(xdp_ring->xsk_pool, budget);
> > + if (!nb_pkts)
> > + return true;
> > +
> > + if (xdp_ring->next_to_use + nb_pkts >= xdp_ring->count) {
> > + nb_processed = xdp_ring->count - xdp_ring->next_to_use;
> > + ice_fill_tx_hw_ring(xdp_ring, descs, nb_processed, &total_bytes);
> > + tx_desc = ICE_TX_DESC(xdp_ring, xdp_ring->next_rs);
> > + tx_desc->cmd_type_offset_bsz |=
> > + cpu_to_le64(ICE_TX_DESC_CMD_RS << ICE_TXD_QW1_CMD_S);
> > + xdp_ring->next_rs = tx_thresh - 1;
> > + xdp_ring->next_to_use = 0;
> > + }
> >
> > - ntc += xdp_ring->count;
> > - xdp_ring->next_to_clean = ntc;
> > + ice_fill_tx_hw_ring(xdp_ring, &descs[nb_processed], nb_pkts - nb_processed,
> > + &total_bytes);
> >
> > - if (xsk_frames)
> > - xsk_tx_completed(xdp_ring->xsk_pool, xsk_frames);
> > + ice_xdp_ring_update_tail(xdp_ring);
> > + ice_update_tx_ring_stats(xdp_ring, nb_pkts, total_bytes);
> >
> > if (xsk_uses_need_wakeup(xdp_ring->xsk_pool))
> > xsk_set_tx_need_wakeup(xdp_ring->xsk_pool);
> >
> > - ice_update_tx_ring_stats(xdp_ring, total_packets, total_bytes);
> > - xmit_done = ice_xmit_zc(xdp_ring, ICE_DFLT_IRQ_WORK);
> > -
> > - return budget > 0 && xmit_done;
> > + return nb_pkts < budget;
> > }
> >
> > /**
> > diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.h b/drivers/net/ethernet/intel/ice/ice_xsk.h
> > index 4c7bd8e9dfc4..0cbb5793b5b8 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_xsk.h
> > +++ b/drivers/net/ethernet/intel/ice/ice_xsk.h
> > @@ -6,19 +6,37 @@
> > #include "ice_txrx.h"
> > #include "ice.h"
> >
> > +#define PKTS_PER_BATCH 8
> > +
> > +#ifdef __clang__
> > +#define loop_unrolled_for _Pragma("clang loop unroll_count(8)") for
> > +#elif __GNUC__ >= 4
> > +#define loop_unrolled_for _Pragma("GCC unroll 8") for
> > +#else
> > +#define loop_unrolled_for for
> > +#endif
> > +
> > struct ice_vsi;
> >
> > #ifdef CONFIG_XDP_SOCKETS
> > int ice_xsk_pool_setup(struct ice_vsi *vsi, struct xsk_buff_pool *pool,
> > u16 qid);
> > int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget);
> > -bool ice_clean_tx_irq_zc(struct ice_tx_ring *xdp_ring, int budget);
> > int ice_xsk_wakeup(struct net_device *netdev, u32 queue_id, u32 flags);
> > bool ice_alloc_rx_bufs_zc(struct ice_rx_ring *rx_ring, u16 count);
> > bool ice_xsk_any_rx_ring_ena(struct ice_vsi *vsi);
> > void ice_xsk_clean_rx_ring(struct ice_rx_ring *rx_ring);
> > void ice_xsk_clean_xdp_ring(struct ice_tx_ring *xdp_ring);
> > +bool ice_xmit_zc(struct ice_tx_ring *xdp_ring, u32 budget, int napi_budget);
> > #else
> > +static inline bool
> > +ice_xmit_zc(struct ice_tx_ring __always_unused *xdp_ring,
> > + u32 __always_unused budget,
> > + int __always_unused napi_budget)
> > +{
> > + return false;
> > +}
> > +
> > static inline int
> > ice_xsk_pool_setup(struct ice_vsi __always_unused *vsi,
> > struct xsk_buff_pool __always_unused *pool,
> > @@ -34,13 +52,6 @@ ice_clean_rx_irq_zc(struct ice_rx_ring __always_unused *rx_ring,
> > return 0;
> > }
> >
> > -static inline bool
> > -ice_clean_tx_irq_zc(struct ice_tx_ring __always_unused *xdp_ring,
> > - int __always_unused budget)
> > -{
> > - return false;
> > -}
> > -
> > static inline bool
> > ice_alloc_rx_bufs_zc(struct ice_rx_ring __always_unused *rx_ring,
> > u16 __always_unused count)
> > --
> > 2.33.1
>
> Thanks,
> Al
Al
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