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Message-Id: <1423044172-23586-1-git-send-email-hariprasad@chelsio.com>
Date: Wed, 4 Feb 2015 15:32:52 +0530
From: Hariprasad Shenai <hariprasad@...lsio.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, leedom@...lsio.com, anish@...lsio.com,
nirranjan@...lsio.com, kumaras@...lsio.com,
Hariprasad Shenai <hariprasad@...lsio.com>
Subject: [PATCHv2 net-next] 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 <ip> -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 <kumaras@...lsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@...lsio.com>
---
V2: fix napi poll return value for repoll, thanks to pointers by
Eric Dumazet <eric.dumazet@...il.com>
drivers/net/ethernet/chelsio/cxgb4/cxgb4.h | 113 +++++++++++++++++++++++
drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c | 16 +++-
drivers/net/ethernet/chelsio/cxgb4/sge.c | 47 +++++++++-
drivers/net/ethernet/chelsio/cxgb4/t4_values.h | 1 +
4 files changed, 174 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
index fb6980a..55019c9 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 5bf490a..041742b 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 6191561..b4b9f60 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c
@@ -43,6 +43,9 @@
#include <linux/export.h>
#include <net/ipv6.h>
#include <net/tcp.h>
+#ifdef CONFIG_NET_RX_BUSY_POLL
+#include <net/busy_poll.h>
+#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 a404844..997ec87 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
--
1.7.1
--
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