From 29322791bc8b4f42fc65734840826e3ddc30921e Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Thu, 1 Sep 2022 12:40:39 +0200 Subject: ice: xsk: change batched Tx descriptor cleaning AF_XDP Tx descriptor cleaning in ice driver currently works in a "lazy" way - descriptors are not cleaned immediately after send. We rather hold on with cleaning until we see that free space in ring drops below particular threshold. This was supposed to reduce the amount of unnecessary work related to cleaning and instead of keeping the ring empty, ring was rather saturated. In AF_XDP realm cleaning Tx descriptors implies producing them to CQ. This is a way of letting know user space that particular descriptor has been sent, as John points out in [0]. We tried to implement serial descriptor cleaning which would be used in conjunction with batched cleaning but it made code base more convoluted and probably harder to maintain in future. Therefore we step away from batched cleaning in a current form in favor of an approach where we set RS bit on every last descriptor from a batch and clean always at the beginning of ice_xmit_zc(). This means that we give up a bit of Tx performance, but this doesn't hurt l2fwd scenario which is way more meaningful than txonly as this can be treaten as AF_XDP based packet generator. l2fwd is not hurt due to the fact that Tx side is much faster than Rx and Rx is the one that has to catch Tx up. FWIW Tx descriptors are still produced in a batched way. [0]: https://lore.kernel.org/bpf/62b0a20232920_3573208ab@john.notmuch/ Fixes: 126cdfe1007a ("ice: xsk: Improve AF_XDP ZC Tx and use batching API") Signed-off-by: Maciej Fijalkowski Tested-by: George Kuruvinakunnel Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/ice/ice_xsk.c | 143 +++++++++++++------------------ 1 file changed, 61 insertions(+), 82 deletions(-) (limited to 'drivers/net/ethernet/intel/ice/ice_xsk.c') diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c index 03ce85f6e6df..8833b66b4e54 100644 --- a/drivers/net/ethernet/intel/ice/ice_xsk.c +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c @@ -788,69 +788,57 @@ ice_clean_xdp_tx_buf(struct ice_tx_ring *xdp_ring, struct ice_tx_buf *tx_buf) } /** - * 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 + * ice_clean_xdp_irq_zc - produce AF_XDP descriptors to CQ + * @xdp_ring: XDP Tx ring */ -static u16 ice_clean_xdp_irq_zc(struct ice_tx_ring *xdp_ring, int napi_budget) +static void ice_clean_xdp_irq_zc(struct ice_tx_ring *xdp_ring) { - u16 tx_thresh = ICE_RING_QUARTER(xdp_ring); - int budget = napi_budget / tx_thresh; - u16 next_dd = xdp_ring->next_dd; - u16 ntc, cleared_dds = 0; - - do { - struct ice_tx_desc *next_dd_desc; - u16 desc_cnt = xdp_ring->count; - struct ice_tx_buf *tx_buf; - u32 xsk_frames; - u16 i; - - 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; + u16 ntc = xdp_ring->next_to_clean; + struct ice_tx_desc *tx_desc; + u16 cnt = xdp_ring->count; + struct ice_tx_buf *tx_buf; + u16 xsk_frames = 0; + u16 last_rs; + int i; - cleared_dds++; - xsk_frames = 0; - if (likely(!xdp_ring->xdp_tx_active)) { - xsk_frames = tx_thresh; - goto skip; - } + last_rs = xdp_ring->next_to_use ? xdp_ring->next_to_use - 1 : cnt - 1; + tx_desc = ICE_TX_DESC(xdp_ring, last_rs); + if ((tx_desc->cmd_type_offset_bsz & + cpu_to_le64(ICE_TX_DESC_DTYPE_DESC_DONE))) { + if (last_rs >= ntc) + xsk_frames = last_rs - ntc + 1; + else + xsk_frames = last_rs + cnt - ntc + 1; + } - ntc = xdp_ring->next_to_clean; + if (!xsk_frames) + return; - for (i = 0; i < tx_thresh; i++) { - tx_buf = &xdp_ring->tx_buf[ntc]; + if (likely(!xdp_ring->xdp_tx_active)) + goto skip; - if (tx_buf->raw_buf) { - ice_clean_xdp_tx_buf(xdp_ring, tx_buf); - tx_buf->raw_buf = NULL; - } else { - xsk_frames++; - } + ntc = xdp_ring->next_to_clean; + for (i = 0; i < xsk_frames; i++) { + tx_buf = &xdp_ring->tx_buf[ntc]; - ntc++; - if (ntc >= xdp_ring->count) - ntc = 0; + if (tx_buf->raw_buf) { + ice_clean_xdp_tx_buf(xdp_ring, tx_buf); + tx_buf->raw_buf = NULL; + } else { + xsk_frames++; } + + ntc++; + if (ntc >= xdp_ring->count) + ntc = 0; + } skip: - xdp_ring->next_to_clean += tx_thresh; - if (xdp_ring->next_to_clean >= desc_cnt) - xdp_ring->next_to_clean -= desc_cnt; - 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); - - xdp_ring->next_dd = next_dd; - - return cleared_dds * tx_thresh; + tx_desc->cmd_type_offset_bsz = 0; + xdp_ring->next_to_clean += xsk_frames; + if (xdp_ring->next_to_clean >= cnt) + xdp_ring->next_to_clean -= cnt; + if (xsk_frames) + xsk_tx_completed(xdp_ring->xsk_pool, xsk_frames); } /** @@ -885,7 +873,6 @@ static void ice_xmit_pkt(struct ice_tx_ring *xdp_ring, struct xdp_desc *desc, static void ice_xmit_pkt_batch(struct ice_tx_ring *xdp_ring, struct xdp_desc *descs, unsigned int *total_bytes) { - u16 tx_thresh = ICE_RING_QUARTER(xdp_ring); u16 ntu = xdp_ring->next_to_use; struct ice_tx_desc *tx_desc; u32 i; @@ -905,13 +892,6 @@ static void ice_xmit_pkt_batch(struct ice_tx_ring *xdp_ring, struct xdp_desc *de } xdp_ring->next_to_use = ntu; - - 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; - } } /** @@ -924,7 +904,6 @@ static void ice_xmit_pkt_batch(struct ice_tx_ring *xdp_ring, struct xdp_desc *de 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 = ICE_RING_QUARTER(xdp_ring); u32 batched, leftover, i; batched = ALIGN_DOWN(nb_pkts, PKTS_PER_BATCH); @@ -933,54 +912,54 @@ static void ice_fill_tx_hw_ring(struct ice_tx_ring *xdp_ring, struct xdp_desc *d ice_xmit_pkt_batch(xdp_ring, &descs[i], total_bytes); for (; i < batched + leftover; i++) ice_xmit_pkt(xdp_ring, &descs[i], total_bytes); +} - if (xdp_ring->next_to_use > xdp_ring->next_rs) { - struct ice_tx_desc *tx_desc; +/** + * ice_set_rs_bit - set RS bit on last produced descriptor (one behind current NTU) + * @xdp_ring: XDP ring to produce the HW Tx descriptors on + */ +static void ice_set_rs_bit(struct ice_tx_ring *xdp_ring) +{ + u16 ntu = xdp_ring->next_to_use ? xdp_ring->next_to_use - 1 : xdp_ring->count - 1; + struct ice_tx_desc *tx_desc; - 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; - } + tx_desc = ICE_TX_DESC(xdp_ring, ntu); + tx_desc->cmd_type_offset_bsz |= + cpu_to_le64(ICE_TX_DESC_CMD_RS << ICE_TXD_QW1_CMD_S); } /** * 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) +bool ice_xmit_zc(struct ice_tx_ring *xdp_ring) { struct xdp_desc *descs = xdp_ring->xsk_pool->tx_descs; - u16 tx_thresh = ICE_RING_QUARTER(xdp_ring); u32 nb_pkts, nb_processed = 0; unsigned int total_bytes = 0; + int budget; + + ice_clean_xdp_irq_zc(xdp_ring); - if (budget < tx_thresh) - budget += ice_clean_xdp_irq_zc(xdp_ring, napi_budget); + budget = ICE_DESC_UNUSED(xdp_ring); + budget = min_t(u16, budget, ICE_RING_QUARTER(xdp_ring)); 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) { - struct ice_tx_desc *tx_desc; - 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; } ice_fill_tx_hw_ring(xdp_ring, &descs[nb_processed], nb_pkts - nb_processed, &total_bytes); + ice_set_rs_bit(xdp_ring); ice_xdp_ring_update_tail(xdp_ring); ice_update_tx_ring_stats(xdp_ring, nb_pkts, total_bytes); -- cgit v1.2.3