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enic: use atomic_t instead of spin_lock in busy poll

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We use spinlock to access a single flag. We can avoid spin_locks by using
atomic variable and atomic_cmpxchg(). Use atomic_cmpxchg to set the flag
for idle to poll. And a simple atomic_set to unlock (set idle from poll).

In napi poll, if gro is enabled, we call napi_gro_receive() to deliver the
packets. Before we call napi_complete(), i.e while re-polling, if low
latency busy poll is called, we use netif_receive_skb() to deliver the packets.
At this point if there are some skb's held in GRO, busy poll could deliver the
packets out of order. So we call napi_gro_flush() to flush skbs before we
move the napi poll to idle.

Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Govindarajulu Varadarajan 2015-06-25 16:02:04 +05:30 committed by David S. Miller
parent 1298267b54
commit f586a33601
2 changed files with 29 additions and 66 deletions
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4
drivers/net/ethernet/cisco/enic/enic_main.c
View File

@ -1208,7 +1208,7 @@ 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]);
enic_poll_unlock_napi(&enic->rq[cq_rq], napi);
return rq_work_done;
}
@ -1414,7 +1414,7 @@ static int enic_poll_msix_rq(struct napi_struct *napi, int budget)
*/
enic_calc_int_moderation(enic, &enic->rq[rq]);
enic_poll_unlock_napi(&enic->rq[rq]);
enic_poll_unlock_napi(&enic->rq[rq], napi);
if (work_done < work_to_do) {
/* Some work done, but not enough to stay in polling,

91
drivers/net/ethernet/cisco/enic/vnic_rq.h
View File

@ -21,6 +21,7 @@
#define _VNIC_RQ_H_
#include <linux/pci.h>
#include <linux/netdevice.h>
#include "vnic_dev.h"
#include "vnic_cq.h"
@ -75,6 +76,12 @@ struct vnic_rq_buf {
uint64_t wr_id;
};
enum enic_poll_state {
ENIC_POLL_STATE_IDLE,
ENIC_POLL_STATE_NAPI,
ENIC_POLL_STATE_POLL
};
struct vnic_rq {
unsigned int index;
struct vnic_dev *vdev;
@ -86,19 +93,7 @@ struct vnic_rq {
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;
atomic_t bpoll_state;
#endif /* CONFIG_NET_RX_BUSY_POLL */
};
@ -215,76 +210,43 @@ static inline int vnic_rq_fill(struct vnic_rq *rq,
#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;
atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE);
}
static inline bool enic_poll_lock_napi(struct vnic_rq *rq)
{
bool rc = true;
int rc = atomic_cmpxchg(&rq->bpoll_state, ENIC_POLL_STATE_IDLE,
ENIC_POLL_STATE_NAPI);
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;
return (rc == ENIC_POLL_STATE_IDLE);
}
static inline bool enic_poll_unlock_napi(struct vnic_rq *rq)
static inline void enic_poll_unlock_napi(struct vnic_rq *rq,
struct napi_struct *napi)
{
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;
WARN_ON(atomic_read(&rq->bpoll_state) != ENIC_POLL_STATE_NAPI);
napi_gro_flush(napi, false);
atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE);
}
static inline bool enic_poll_lock_poll(struct vnic_rq *rq)
{
bool rc = true;
int rc = atomic_cmpxchg(&rq->bpoll_state, ENIC_POLL_STATE_IDLE,
ENIC_POLL_STATE_POLL);
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;
return (rc == ENIC_POLL_STATE_IDLE);
}
static inline bool enic_poll_unlock_poll(struct vnic_rq *rq)
static inline void 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;
WARN_ON(atomic_read(&rq->bpoll_state) != ENIC_POLL_STATE_POLL);
atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE);
}
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;
return atomic_read(&rq->bpoll_state) & ENIC_POLL_STATE_POLL;
}
#else
@ -298,7 +260,8 @@ static inline bool enic_poll_lock_napi(struct vnic_rq *rq)
return true;
}
static inline bool enic_poll_unlock_napi(struct vnic_rq *rq)
static inline bool enic_poll_unlock_napi(struct vnic_rq *rq,
struct napi_struct *napi)
{
return false;
}