diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/eventpoll.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 341251421ced..5420767c9b68 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -42,6 +42,7 @@ #include <linux/seq_file.h> #include <linux/compat.h> #include <linux/rculist.h> +#include <net/busy_poll.h> /* * LOCKING: @@ -224,6 +225,11 @@ struct eventpoll { /* used to optimize loop detection check */ int visited; struct list_head visited_list_link; + +#ifdef CONFIG_NET_RX_BUSY_POLL + /* used to track busy poll napi_id */ + unsigned int napi_id; +#endif }; /* Wait structure used by the poll hooks */ @@ -384,6 +390,77 @@ static inline int ep_events_available(struct eventpoll *ep) return !list_empty(&ep->rdllist) || ep->ovflist != EP_UNACTIVE_PTR; } +#ifdef CONFIG_NET_RX_BUSY_POLL +static bool ep_busy_loop_end(void *p, unsigned long start_time) +{ + struct eventpoll *ep = p; + + return ep_events_available(ep) || busy_loop_timeout(start_time); +} +#endif /* CONFIG_NET_RX_BUSY_POLL */ + +/* + * Busy poll if globally on and supporting sockets found && no events, + * busy loop will return if need_resched or ep_events_available. + * + * we must do our busy polling with irqs enabled + */ +static void ep_busy_loop(struct eventpoll *ep, int nonblock) +{ +#ifdef CONFIG_NET_RX_BUSY_POLL + unsigned int napi_id = READ_ONCE(ep->napi_id); + + if ((napi_id >= MIN_NAPI_ID) && net_busy_loop_on()) + napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep); +#endif +} + +static inline void ep_reset_busy_poll_napi_id(struct eventpoll *ep) +{ +#ifdef CONFIG_NET_RX_BUSY_POLL + if (ep->napi_id) + ep->napi_id = 0; +#endif +} + +/* + * Set epoll busy poll NAPI ID from sk. + */ +static inline void ep_set_busy_poll_napi_id(struct epitem *epi) +{ +#ifdef CONFIG_NET_RX_BUSY_POLL + struct eventpoll *ep; + unsigned int napi_id; + struct socket *sock; + struct sock *sk; + int err; + + if (!net_busy_loop_on()) + return; + + sock = sock_from_file(epi->ffd.file, &err); + if (!sock) + return; + + sk = sock->sk; + if (!sk) + return; + + napi_id = READ_ONCE(sk->sk_napi_id); + ep = epi->ep; + + /* Non-NAPI IDs can be rejected + * or + * Nothing to do if we already have this ID + */ + if (napi_id < MIN_NAPI_ID || napi_id == ep->napi_id) + return; + + /* record NAPI ID for use in next busy poll */ + ep->napi_id = napi_id; +#endif +} + /** * ep_call_nested - Perform a bound (possibly) nested call, by checking * that the recursion limit is not exceeded, and that @@ -1022,6 +1099,8 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k spin_lock_irqsave(&ep->lock, flags); + ep_set_busy_poll_napi_id(epi); + /* * If the event mask does not contain any poll(2) event, we consider the * descriptor to be disabled. This condition is likely the effect of the @@ -1363,6 +1442,9 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, /* We have to drop the new item inside our item list to keep track of it */ spin_lock_irqsave(&ep->lock, flags); + /* record NAPI ID of new item if present */ + ep_set_busy_poll_napi_id(epi); + /* If the file is already "ready" we drop it inside the ready list */ if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) { list_add_tail(&epi->rdllink, &ep->rdllist); @@ -1637,10 +1719,21 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, } fetch_events: + + if (!ep_events_available(ep)) + ep_busy_loop(ep, timed_out); + spin_lock_irqsave(&ep->lock, flags); if (!ep_events_available(ep)) { /* + * Busy poll timed out. Drop NAPI ID for now, we can add + * it back in when we have moved a socket with a valid NAPI + * ID onto the ready list. + */ + ep_reset_busy_poll_napi_id(ep); + + /* * We don't have any available event to return to the caller. * We need to sleep here, and we will be wake up by * ep_poll_callback() when events will become available. |