diff options
Diffstat (limited to 'include/net/busy_poll.h')
| -rw-r--r-- | include/net/busy_poll.h | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h new file mode 100644 index 00000000000..76f03408774 --- /dev/null +++ b/include/net/busy_poll.h @@ -0,0 +1,183 @@ +/* + * Low Latency Sockets + * Copyright(c) 2013 Intel Corporation. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. + * + * Author: Eliezer Tamir + * + * Contact Information: + * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net> + */ + +#ifndef _LINUX_NET_LL_POLL_H +#define _LINUX_NET_LL_POLL_H + +#include <linux/netdevice.h> +#include <net/ip.h> + +#ifdef CONFIG_NET_LL_RX_POLL + +struct napi_struct; +extern unsigned int sysctl_net_ll_read __read_mostly; +extern unsigned int sysctl_net_ll_poll __read_mostly; + +/* return values from ndo_ll_poll */ +#define LL_FLUSH_FAILED -1 +#define LL_FLUSH_BUSY -2 + +static inline bool net_busy_loop_on(void) +{ + return sysctl_net_ll_poll; +} + +/* a wrapper to make debug_smp_processor_id() happy + * we can use sched_clock() because we don't care much about precision + * we only care that the average is bounded + */ +#ifdef CONFIG_DEBUG_PREEMPT +static inline u64 busy_loop_us_clock(void) +{ + u64 rc; + + preempt_disable_notrace(); + rc = sched_clock(); + preempt_enable_no_resched_notrace(); + + return rc >> 10; +} +#else /* CONFIG_DEBUG_PREEMPT */ +static inline u64 busy_loop_us_clock(void) +{ + return sched_clock() >> 10; +} +#endif /* CONFIG_DEBUG_PREEMPT */ + +static inline unsigned long sk_busy_loop_end_time(struct sock *sk) +{ + return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec); +} + +/* in poll/select we use the global sysctl_net_ll_poll value */ +static inline unsigned long busy_loop_end_time(void) +{ + return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_ll_poll); +} + +static inline bool sk_can_busy_loop(struct sock *sk) +{ + return sk->sk_ll_usec && sk->sk_napi_id && + !need_resched() && !signal_pending(current); +} + + +static inline bool busy_loop_timeout(unsigned long end_time) +{ + unsigned long now = busy_loop_us_clock(); + + return time_after(now, end_time); +} + +/* when used in sock_poll() nonblock is known at compile time to be true + * so the loop and end_time will be optimized out + */ +static inline bool sk_busy_loop(struct sock *sk, int nonblock) +{ + unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0; + const struct net_device_ops *ops; + struct napi_struct *napi; + int rc = false; + + /* + * rcu read lock for napi hash + * bh so we don't race with net_rx_action + */ + rcu_read_lock_bh(); + + napi = napi_by_id(sk->sk_napi_id); + if (!napi) + goto out; + + ops = napi->dev->netdev_ops; + if (!ops->ndo_ll_poll) + goto out; + + do { + rc = ops->ndo_ll_poll(napi); + + if (rc == LL_FLUSH_FAILED) + break; /* permanent failure */ + + if (rc > 0) + /* local bh are disabled so it is ok to use _BH */ + NET_ADD_STATS_BH(sock_net(sk), + LINUX_MIB_LOWLATENCYRXPACKETS, rc); + + } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) && + !need_resched() && !busy_loop_timeout(end_time)); + + rc = !skb_queue_empty(&sk->sk_receive_queue); +out: + rcu_read_unlock_bh(); + return rc; +} + +/* used in the NIC receive handler to mark the skb */ +static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi) +{ + skb->napi_id = napi->napi_id; +} + +/* used in the protocol hanlder to propagate the napi_id to the socket */ +static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb) +{ + sk->sk_napi_id = skb->napi_id; +} + +#else /* CONFIG_NET_LL_RX_POLL */ +static inline unsigned long net_busy_loop_on(void) +{ + return 0; +} + +static inline unsigned long busy_loop_end_time(void) +{ + return 0; +} + +static inline bool sk_can_busy_loop(struct sock *sk) +{ + return false; +} + +static inline bool sk_busy_poll(struct sock *sk, int nonblock) +{ + return false; +} + +static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi) +{ +} + +static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb) +{ +} + +static inline bool busy_loop_timeout(unsigned long end_time) +{ + return true; +} + +#endif /* CONFIG_NET_LL_RX_POLL */ +#endif /* _LINUX_NET_LL_POLL_H */ |