From: Hariprasad Shenai Date: Wed, 4 Feb 2015 10:02:52 +0000 (+0530) Subject: cxgb4: Add low latency socket busy_poll support X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=3a336cb17183b29827fdffaffb5e62f8912f5ca1;p=openwrt%2Fstaging%2Fblogic.git cxgb4: Add low latency socket busy_poll support cxgb_busy_poll, corresponding to ndo_busy_poll, gets called by the socket waiting for data. With busy_poll enabled, improvement is seen in latency numbers as observed by collecting netperf TCP_RR numbers. Below are latency number, with and without busy-poll, in a switched environment for a particular msg size: netperf command: netperf -4 -H -l 30 -t TCP_RR -- -r1,1 Latency without busy-poll: ~16.25 us Latency with busy-poll : ~08.79 us Based on original work by Kumar Sanghvi Signed-off-by: Hariprasad Shenai Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h index fb6980a09981..55019c93387d 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h +++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h @@ -476,6 +476,22 @@ struct sge_rspq { /* state for an SGE response queue */ struct adapter *adap; struct net_device *netdev; /* associated net device */ rspq_handler_t handler; +#ifdef CONFIG_NET_RX_BUSY_POLL +#define CXGB_POLL_STATE_IDLE 0 +#define CXGB_POLL_STATE_NAPI BIT(0) /* NAPI owns this poll */ +#define CXGB_POLL_STATE_POLL BIT(1) /* poll owns this poll */ +#define CXGB_POLL_STATE_NAPI_YIELD BIT(2) /* NAPI yielded this poll */ +#define CXGB_POLL_STATE_POLL_YIELD BIT(3) /* poll yielded this poll */ +#define CXGB_POLL_YIELD (CXGB_POLL_STATE_NAPI_YIELD | \ + CXGB_POLL_STATE_POLL_YIELD) +#define CXGB_POLL_LOCKED (CXGB_POLL_STATE_NAPI | \ + CXGB_POLL_STATE_POLL) +#define CXGB_POLL_USER_PEND (CXGB_POLL_STATE_POLL | \ + CXGB_POLL_STATE_POLL_YIELD) + unsigned int bpoll_state; + spinlock_t bpoll_lock; /* lock for busy poll */ +#endif /* CONFIG_NET_RX_BUSY_POLL */ + }; struct sge_eth_stats { /* Ethernet queue statistics */ @@ -880,6 +896,102 @@ static inline struct adapter *netdev2adap(const struct net_device *dev) return netdev2pinfo(dev)->adapter; } +#ifdef CONFIG_NET_RX_BUSY_POLL +static inline void cxgb_busy_poll_init_lock(struct sge_rspq *q) +{ + spin_lock_init(&q->bpoll_lock); + q->bpoll_state = CXGB_POLL_STATE_IDLE; +} + +static inline bool cxgb_poll_lock_napi(struct sge_rspq *q) +{ + bool rc = true; + + spin_lock(&q->bpoll_lock); + if (q->bpoll_state & CXGB_POLL_LOCKED) { + q->bpoll_state |= CXGB_POLL_STATE_NAPI_YIELD; + rc = false; + } else { + q->bpoll_state = CXGB_POLL_STATE_NAPI; + } + spin_unlock(&q->bpoll_lock); + return rc; +} + +static inline bool cxgb_poll_unlock_napi(struct sge_rspq *q) +{ + bool rc = false; + + spin_lock(&q->bpoll_lock); + if (q->bpoll_state & CXGB_POLL_STATE_POLL_YIELD) + rc = true; + q->bpoll_state = CXGB_POLL_STATE_IDLE; + spin_unlock(&q->bpoll_lock); + return rc; +} + +static inline bool cxgb_poll_lock_poll(struct sge_rspq *q) +{ + bool rc = true; + + spin_lock_bh(&q->bpoll_lock); + if (q->bpoll_state & CXGB_POLL_LOCKED) { + q->bpoll_state |= CXGB_POLL_STATE_POLL_YIELD; + rc = false; + } else { + q->bpoll_state |= CXGB_POLL_STATE_POLL; + } + spin_unlock_bh(&q->bpoll_lock); + return rc; +} + +static inline bool cxgb_poll_unlock_poll(struct sge_rspq *q) +{ + bool rc = false; + + spin_lock_bh(&q->bpoll_lock); + if (q->bpoll_state & CXGB_POLL_STATE_POLL_YIELD) + rc = true; + q->bpoll_state = CXGB_POLL_STATE_IDLE; + spin_unlock_bh(&q->bpoll_lock); + return rc; +} + +static inline bool cxgb_poll_busy_polling(struct sge_rspq *q) +{ + return q->bpoll_state & CXGB_POLL_USER_PEND; +} +#else +static inline void cxgb_busy_poll_init_lock(struct sge_rspq *q) +{ +} + +static inline bool cxgb_poll_lock_napi(struct sge_rspq *q) +{ + return true; +} + +static inline bool cxgb_poll_unlock_napi(struct sge_rspq *q) +{ + return false; +} + +static inline bool cxgb_poll_lock_poll(struct sge_rspq *q) +{ + return false; +} + +static inline bool cxgb_poll_unlock_poll(struct sge_rspq *q) +{ + return false; +} + +static inline bool cxgb_poll_busy_polling(struct sge_rspq *q) +{ + return false; +} +#endif /* CONFIG_NET_RX_BUSY_POLL */ + void t4_os_portmod_changed(const struct adapter *adap, int port_id); void t4_os_link_changed(struct adapter *adap, int port_id, int link_stat); @@ -908,6 +1020,7 @@ irqreturn_t t4_sge_intr_msix(int irq, void *cookie); int t4_sge_init(struct adapter *adap); void t4_sge_start(struct adapter *adap); void t4_sge_stop(struct adapter *adap); +int cxgb_busy_poll(struct napi_struct *napi); extern int dbfifo_int_thresh; #define for_each_port(adapter, iter) \ diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c index 5bf490a781aa..041742b5e0e8 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c +++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c @@ -923,8 +923,14 @@ static void quiesce_rx(struct adapter *adap) for (i = 0; i < ARRAY_SIZE(adap->sge.ingr_map); i++) { struct sge_rspq *q = adap->sge.ingr_map[i]; - if (q && q->handler) + if (q && q->handler) { napi_disable(&q->napi); + local_bh_disable(); + while (!cxgb_poll_lock_napi(q)) + mdelay(1); + local_bh_enable(); + } + } } @@ -940,8 +946,10 @@ static void enable_rx(struct adapter *adap) if (!q) continue; - if (q->handler) + if (q->handler) { + cxgb_busy_poll_init_lock(q); napi_enable(&q->napi); + } /* 0-increment GTS to start the timer and enable interrupts */ t4_write_reg(adap, MYPF_REG(SGE_PF_GTS_A), SEINTARM_V(q->intr_params) | @@ -4563,6 +4571,10 @@ static const struct net_device_ops cxgb4_netdev_ops = { #ifdef CONFIG_NET_POLL_CONTROLLER .ndo_poll_controller = cxgb_netpoll, #endif +#ifdef CONFIG_NET_RX_BUSY_POLL + .ndo_busy_poll = cxgb_busy_poll, +#endif + }; void t4_fatal_err(struct adapter *adap) diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c b/drivers/net/ethernet/chelsio/cxgb4/sge.c index 619156112b21..b4b9f6048fe7 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/sge.c +++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c @@ -43,6 +43,9 @@ #include #include #include +#ifdef CONFIG_NET_RX_BUSY_POLL +#include +#endif /* CONFIG_NET_RX_BUSY_POLL */ #include "cxgb4.h" #include "t4_regs.h" #include "t4_values.h" @@ -1720,6 +1723,7 @@ static void do_gro(struct sge_eth_rxq *rxq, const struct pkt_gl *gl, skb->truesize += skb->data_len; skb->ip_summed = CHECKSUM_UNNECESSARY; skb_record_rx_queue(skb, rxq->rspq.idx); + skb_mark_napi_id(skb, &rxq->rspq.napi); if (rxq->rspq.netdev->features & NETIF_F_RXHASH) skb_set_hash(skb, (__force u32)pkt->rsshdr.hash_val, PKT_HASH_TYPE_L3); @@ -1763,6 +1767,7 @@ int t4_ethrx_handler(struct sge_rspq *q, const __be64 *rsp, csum_ok = pkt->csum_calc && !pkt->err_vec && (q->netdev->features & NETIF_F_RXCSUM); if ((pkt->l2info & htonl(RXF_TCP_F)) && + !(cxgb_poll_busy_polling(q)) && (q->netdev->features & NETIF_F_GRO) && csum_ok && !pkt->ip_frag) { do_gro(rxq, si, pkt); return 0; @@ -1801,6 +1806,7 @@ int t4_ethrx_handler(struct sge_rspq *q, const __be64 *rsp, __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), ntohs(pkt->vlan)); rxq->stats.vlan_ex++; } + skb_mark_napi_id(skb, &q->napi); netif_receive_skb(skb); return 0; } @@ -1963,6 +1969,38 @@ static int process_responses(struct sge_rspq *q, int budget) return budget - budget_left; } +#ifdef CONFIG_NET_RX_BUSY_POLL +int cxgb_busy_poll(struct napi_struct *napi) +{ + struct sge_rspq *q = container_of(napi, struct sge_rspq, napi); + unsigned int params, work_done; + u32 val; + + if (!cxgb_poll_lock_poll(q)) + return LL_FLUSH_BUSY; + + work_done = process_responses(q, 4); + params = QINTR_TIMER_IDX(TIMERREG_COUNTER0_X) | QINTR_CNT_EN; + q->next_intr_params = params; + val = CIDXINC_V(work_done) | SEINTARM_V(params); + + /* If we don't have access to the new User GTS (T5+), use the old + * doorbell mechanism; otherwise use the new BAR2 mechanism. + */ + if (unlikely(!q->bar2_addr)) + t4_write_reg(q->adap, MYPF_REG(SGE_PF_GTS_A), + val | INGRESSQID_V((u32)q->cntxt_id)); + else { + writel(val | INGRESSQID_V(q->bar2_qid), + q->bar2_addr + SGE_UDB_GTS); + wmb(); + } + + cxgb_poll_unlock_poll(q); + return work_done; +} +#endif /* CONFIG_NET_RX_BUSY_POLL */ + /** * napi_rx_handler - the NAPI handler for Rx processing * @napi: the napi instance @@ -1978,9 +2016,13 @@ static int napi_rx_handler(struct napi_struct *napi, int budget) { unsigned int params; struct sge_rspq *q = container_of(napi, struct sge_rspq, napi); - int work_done = process_responses(q, budget); + int work_done; u32 val; + if (!cxgb_poll_lock_napi(q)) + return budget; + + work_done = process_responses(q, budget); if (likely(work_done < budget)) { int timer_index; @@ -2018,6 +2060,7 @@ static int napi_rx_handler(struct napi_struct *napi, int budget) q->bar2_addr + SGE_UDB_GTS); wmb(); } + cxgb_poll_unlock_napi(q); return work_done; } @@ -2341,6 +2384,7 @@ int t4_sge_alloc_rxq(struct adapter *adap, struct sge_rspq *iq, bool fwevtq, goto err; netif_napi_add(dev, &iq->napi, napi_rx_handler, 64); + napi_hash_add(&iq->napi); iq->cur_desc = iq->desc; iq->cidx = 0; iq->gen = 1; @@ -2598,6 +2642,7 @@ static void free_rspq_fl(struct adapter *adap, struct sge_rspq *rq, rq->cntxt_id, fl_id, 0xffff); dma_free_coherent(adap->pdev_dev, (rq->size + 1) * rq->iqe_len, rq->desc, rq->phys_addr); + napi_hash_del(&rq->napi); netif_napi_del(&rq->napi); rq->netdev = NULL; rq->cntxt_id = rq->abs_id = 0; diff --git a/drivers/net/ethernet/chelsio/cxgb4/t4_values.h b/drivers/net/ethernet/chelsio/cxgb4/t4_values.h index a40484432ebf..997ec87470c7 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/t4_values.h +++ b/drivers/net/ethernet/chelsio/cxgb4/t4_values.h @@ -59,6 +59,7 @@ /* GTS register */ #define SGE_TIMERREGS 6 +#define TIMERREG_COUNTER0_X 0 /* T5 and later support a new BAR2-based doorbell mechanism for Egress Queues. * The User Doorbells are each 128 bytes in length with a Simple Doorbell at