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Date: Wed, 18 Jun 2014 13:08:07 +0530
From: Govindarajulu Varadarajan <_govind@....com>
To: davem@...emloft.net, netdev@...r.kernel.org
Cc: ssujith@...co.com, benve@...co.com,
Govindarajulu Varadarajan <_govind@....com>
Subject: [PATCH net-next v2 7/8] enic: add low latency socket busy_poll support
This patch adds support for low latency busy_poll.
* Introduce drivers ndo_busy_poll function enic_busy_poll, which is called by
socket waiting for data.
* Introduce locking between napi_poll nad busy_poll
* enic_busy_poll cleans up all the rx pkts possible. While in busy_poll, rq
holds the state ENIC_POLL_STATE_POLL. While in napi_poll, rq holds the state
ENIC_POLL_STATE_NAPI.
* in napi_poll we return if we are in busy_poll. Incase of INTx & msix, we just
service wq and return if busy_poll is going on.
Signed-off-by: Govindarajulu Varadarajan <_govind@....com>
---
drivers/net/ethernet/cisco/enic/enic_main.c | 85 ++++++++++++++++---
drivers/net/ethernet/cisco/enic/vnic_rq.h | 122 ++++++++++++++++++++++++++++
2 files changed, 195 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
index 5448df2..d4918ee 100644
--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -42,6 +42,9 @@
#ifdef CONFIG_RFS_ACCEL
#include <linux/cpu_rmap.h>
#endif
+#ifdef CONFIG_NET_RX_BUSY_POLL
+#include <net/busy_poll.h>
+#endif
#include "cq_enet_desc.h"
#include "vnic_dev.h"
@@ -1053,10 +1056,12 @@ static void enic_rq_indicate_buf(struct vnic_rq *rq,
if (vlan_stripped)
__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlan_tci);
- if (netdev->features & NETIF_F_GRO)
- napi_gro_receive(&enic->napi[q_number], skb);
- else
+ skb_mark_napi_id(skb, &enic->napi[rq->index]);
+ if (enic_poll_busy_polling(rq) ||
+ !(netdev->features & NETIF_F_GRO))
netif_receive_skb(skb);
+ else
+ napi_gro_receive(&enic->napi[q_number], skb);
if (enic->rx_coalesce_setting.use_adaptive_rx_coalesce)
enic_intr_update_pkt_size(&cq->pkt_size_counter,
bytes_written);
@@ -1093,16 +1098,22 @@ static int enic_poll(struct napi_struct *napi, int budget)
unsigned int work_done, rq_work_done = 0, wq_work_done;
int err;
- /* Service RQ (first) and WQ
- */
+ wq_work_done = vnic_cq_service(&enic->cq[cq_wq], wq_work_to_do,
+ enic_wq_service, NULL);
+
+ if (!enic_poll_lock_napi(&enic->rq[cq_rq])) {
+ if (wq_work_done > 0)
+ vnic_intr_return_credits(&enic->intr[intr],
+ wq_work_done,
+ 0 /* dont unmask intr */,
+ 0 /* dont reset intr timer */);
+ return rq_work_done;
+ }
if (budget > 0)
rq_work_done = vnic_cq_service(&enic->cq[cq_rq],
rq_work_to_do, enic_rq_service, NULL);
- wq_work_done = vnic_cq_service(&enic->cq[cq_wq],
- wq_work_to_do, enic_wq_service, NULL);
-
/* Accumulate intr event credits for this polling
* cycle. An intr event is the completion of a
* a WQ or RQ packet.
@@ -1134,6 +1145,7 @@ static int enic_poll(struct napi_struct *napi, int budget)
napi_complete(napi);
vnic_intr_unmask(&enic->intr[intr]);
}
+ enic_poll_unlock_napi(&enic->rq[cq_rq]);
return rq_work_done;
}
@@ -1234,6 +1246,34 @@ static void enic_set_rx_cpu_rmap(struct enic *enic)
#endif /* CONFIG_RFS_ACCEL */
+#ifdef CONFIG_NET_RX_BUSY_POLL
+int enic_busy_poll(struct napi_struct *napi)
+{
+ struct net_device *netdev = napi->dev;
+ struct enic *enic = netdev_priv(netdev);
+ unsigned int rq = (napi - &enic->napi[0]);
+ unsigned int cq = enic_cq_rq(enic, rq);
+ unsigned int intr = enic_msix_rq_intr(enic, rq);
+ unsigned int work_to_do = -1; /* clean all pkts possible */
+ unsigned int work_done;
+
+ if (!enic_poll_lock_poll(&enic->rq[rq]))
+ return LL_FLUSH_BUSY;
+ work_done = vnic_cq_service(&enic->cq[cq], work_to_do,
+ enic_rq_service, NULL);
+
+ if (work_done > 0)
+ vnic_intr_return_credits(&enic->intr[intr],
+ work_done, 0, 0);
+ vnic_rq_fill(&enic->rq[rq], enic_rq_alloc_buf);
+ if (enic->rx_coalesce_setting.use_adaptive_rx_coalesce)
+ enic_calc_int_moderation(enic, &enic->rq[rq]);
+ enic_poll_unlock_poll(&enic->rq[rq]);
+
+ return work_done;
+}
+#endif /* CONFIG_NET_RX_BUSY_POLL */
+
static int enic_poll_msix(struct napi_struct *napi, int budget)
{
struct net_device *netdev = napi->dev;
@@ -1245,6 +1285,8 @@ static int enic_poll_msix(struct napi_struct *napi, int budget)
unsigned int work_done = 0;
int err;
+ if (!enic_poll_lock_napi(&enic->rq[rq]))
+ return work_done;
/* Service RQ
*/
@@ -1290,6 +1332,7 @@ static int enic_poll_msix(struct napi_struct *napi, int budget)
enic_set_int_moderation(enic, &enic->rq[rq]);
vnic_intr_unmask(&enic->intr[intr]);
}
+ enic_poll_unlock_napi(&enic->rq[rq]);
return work_done;
}
@@ -1538,8 +1581,10 @@ static int enic_open(struct net_device *netdev)
netif_tx_wake_all_queues(netdev);
- for (i = 0; i < enic->rq_count; i++)
+ for (i = 0; i < enic->rq_count; i++) {
+ enic_busy_poll_init_lock(&enic->rq[i]);
napi_enable(&enic->napi[i]);
+ }
enic_dev_enable(enic);
@@ -1578,8 +1623,13 @@ static int enic_stop(struct net_device *netdev)
enic_dev_disable(enic);
- for (i = 0; i < enic->rq_count; i++)
+ local_bh_disable();
+ for (i = 0; i < enic->rq_count; i++) {
napi_disable(&enic->napi[i]);
+ while (!enic_poll_lock_napi(&enic->rq[i]))
+ mdelay(1);
+ }
+ local_bh_enable();
netif_carrier_off(netdev);
netif_tx_disable(netdev);
@@ -2070,6 +2120,9 @@ static const struct net_device_ops enic_netdev_dynamic_ops = {
#ifdef CONFIG_RFS_ACCEL
.ndo_rx_flow_steer = enic_rx_flow_steer,
#endif
+#ifdef CONFIG_NET_RX_BUSY_POLL
+ .ndo_busy_poll = enic_busy_poll,
+#endif
};
static const struct net_device_ops enic_netdev_ops = {
@@ -2093,14 +2146,19 @@ static const struct net_device_ops enic_netdev_ops = {
#ifdef CONFIG_RFS_ACCEL
.ndo_rx_flow_steer = enic_rx_flow_steer,
#endif
+#ifdef CONFIG_NET_RX_BUSY_POLL
+ .ndo_busy_poll = enic_busy_poll,
+#endif
};
static void enic_dev_deinit(struct enic *enic)
{
unsigned int i;
- for (i = 0; i < enic->rq_count; i++)
+ for (i = 0; i < enic->rq_count; i++) {
+ napi_hash_del(&enic->napi[i]);
netif_napi_del(&enic->napi[i]);
+ }
enic_free_vnic_resources(enic);
enic_clear_intr_mode(enic);
@@ -2166,11 +2224,14 @@ static int enic_dev_init(struct enic *enic)
switch (vnic_dev_get_intr_mode(enic->vdev)) {
default:
netif_napi_add(netdev, &enic->napi[0], enic_poll, 64);
+ napi_hash_add(&enic->napi[0]);
break;
case VNIC_DEV_INTR_MODE_MSIX:
- for (i = 0; i < enic->rq_count; i++)
+ for (i = 0; i < enic->rq_count; i++) {
netif_napi_add(netdev, &enic->napi[i],
enic_poll_msix, 64);
+ napi_hash_add(&enic->napi[i]);
+ }
break;
}
diff --git a/drivers/net/ethernet/cisco/enic/vnic_rq.h b/drivers/net/ethernet/cisco/enic/vnic_rq.h
index ee7bc95..8111d52 100644
--- a/drivers/net/ethernet/cisco/enic/vnic_rq.h
+++ b/drivers/net/ethernet/cisco/enic/vnic_rq.h
@@ -85,6 +85,21 @@ struct vnic_rq {
struct vnic_rq_buf *to_clean;
void *os_buf_head;
unsigned int pkts_outstanding;
+#ifdef CONFIG_NET_RX_BUSY_POLL
+#define ENIC_POLL_STATE_IDLE 0
+#define ENIC_POLL_STATE_NAPI (1 << 0) /* NAPI owns this poll */
+#define ENIC_POLL_STATE_POLL (1 << 1) /* poll owns this poll */
+#define ENIC_POLL_STATE_NAPI_YIELD (1 << 2) /* NAPI yielded this poll */
+#define ENIC_POLL_STATE_POLL_YIELD (1 << 3) /* poll yielded this poll */
+#define ENIC_POLL_YIELD (ENIC_POLL_STATE_NAPI_YIELD | \
+ ENIC_POLL_STATE_POLL_YIELD)
+#define ENIC_POLL_LOCKED (ENIC_POLL_STATE_NAPI | \
+ ENIC_POLL_STATE_POLL)
+#define ENIC_POLL_USER_PEND (ENIC_POLL_STATE_POLL | \
+ ENIC_POLL_STATE_POLL_YIELD)
+ unsigned int bpoll_state;
+ spinlock_t bpoll_lock;
+#endif /* CONFIG_NET_RX_BUSY_POLL */
};
static inline unsigned int vnic_rq_desc_avail(struct vnic_rq *rq)
@@ -197,6 +212,113 @@ static inline int vnic_rq_fill(struct vnic_rq *rq,
return 0;
}
+#ifdef CONFIG_NET_RX_BUSY_POLL
+static inline void enic_busy_poll_init_lock(struct vnic_rq *rq)
+{
+ spin_lock_init(&rq->bpoll_lock);
+ rq->bpoll_state = ENIC_POLL_STATE_IDLE;
+}
+
+static inline bool enic_poll_lock_napi(struct vnic_rq *rq)
+{
+ bool rc = true;
+
+ spin_lock(&rq->bpoll_lock);
+ if (rq->bpoll_state & ENIC_POLL_LOCKED) {
+ WARN_ON(rq->bpoll_state & ENIC_POLL_STATE_NAPI);
+ rq->bpoll_state |= ENIC_POLL_STATE_NAPI_YIELD;
+ rc = false;
+ } else {
+ rq->bpoll_state = ENIC_POLL_STATE_NAPI;
+ }
+ spin_unlock(&rq->bpoll_lock);
+
+ return rc;
+}
+
+static inline bool enic_poll_unlock_napi(struct vnic_rq *rq)
+{
+ bool rc = false;
+
+ spin_lock(&rq->bpoll_lock);
+ WARN_ON(rq->bpoll_state &
+ (ENIC_POLL_STATE_POLL | ENIC_POLL_STATE_NAPI_YIELD));
+ if (rq->bpoll_state & ENIC_POLL_STATE_POLL_YIELD)
+ rc = true;
+ rq->bpoll_state = ENIC_POLL_STATE_IDLE;
+ spin_unlock(&rq->bpoll_lock);
+
+ return rc;
+}
+
+static inline bool enic_poll_lock_poll(struct vnic_rq *rq)
+{
+ bool rc = true;
+
+ spin_lock_bh(&rq->bpoll_lock);
+ if (rq->bpoll_state & ENIC_POLL_LOCKED) {
+ rq->bpoll_state |= ENIC_POLL_STATE_POLL_YIELD;
+ rc = false;
+ } else {
+ rq->bpoll_state |= ENIC_POLL_STATE_POLL;
+ }
+ spin_unlock_bh(&rq->bpoll_lock);
+
+ return rc;
+}
+
+static inline bool enic_poll_unlock_poll(struct vnic_rq *rq)
+{
+ bool rc = false;
+
+ spin_lock_bh(&rq->bpoll_lock);
+ WARN_ON(rq->bpoll_state & ENIC_POLL_STATE_NAPI);
+ if (rq->bpoll_state & ENIC_POLL_STATE_POLL_YIELD)
+ rc = true;
+ rq->bpoll_state = ENIC_POLL_STATE_IDLE;
+ spin_unlock_bh(&rq->bpoll_lock);
+
+ return rc;
+}
+
+static inline bool enic_poll_busy_polling(struct vnic_rq *rq)
+{
+ WARN_ON(!(rq->bpoll_state & ENIC_POLL_LOCKED));
+ return rq->bpoll_state & ENIC_POLL_USER_PEND;
+}
+
+#else
+
+static inline void enic_busy_poll_init_lock(struct vnic_rq *rq)
+{
+}
+
+static inline bool enic_poll_lock_napi(struct vnic_rq *rq)
+{
+ return true;
+}
+
+static inline bool enic_poll_unlock_napi(struct vnic_rq *rq)
+{
+ return false;
+}
+
+static inline bool enic_poll_lock_poll(struct vnic_rq *rq)
+{
+ return false;
+}
+
+static inline bool enic_poll_unlock_poll(struct vnic_rq *rq)
+{
+ return false;
+}
+
+static inline bool enic_poll_ll_polling(struct vnic_rq *rq)
+{
+ return false;
+}
+#endif /* CONFIG_NET_RX_BUSY_POLL */
+
void vnic_rq_free(struct vnic_rq *rq);
int vnic_rq_alloc(struct vnic_dev *vdev, struct vnic_rq *rq, unsigned int index,
unsigned int desc_count, unsigned int desc_size);
--
2.0.0
--
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