2 * net busy poll support
3 * Copyright(c) 2013 Intel Corporation.
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
18 * Author: Eliezer Tamir
20 * Contact Information:
21 * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
24 #ifndef _LINUX_NET_BUSY_POLL_H
25 #define _LINUX_NET_BUSY_POLL_H
27 #include <linux/netdevice.h>
30 #ifdef CONFIG_NET_LL_RX_POLL
33 extern unsigned int sysctl_net_ll_read __read_mostly;
34 extern unsigned int sysctl_net_ll_poll __read_mostly;
36 /* return values from ndo_ll_poll */
37 #define LL_FLUSH_FAILED -1
38 #define LL_FLUSH_BUSY -2
40 static inline bool net_busy_loop_on(void)
42 return sysctl_net_ll_poll;
45 /* a wrapper to make debug_smp_processor_id() happy
46 * we can use sched_clock() because we don't care much about precision
47 * we only care that the average is bounded
49 #ifdef CONFIG_DEBUG_PREEMPT
50 static inline u64 busy_loop_us_clock(void)
54 preempt_disable_notrace();
56 preempt_enable_no_resched_notrace();
60 #else /* CONFIG_DEBUG_PREEMPT */
61 static inline u64 busy_loop_us_clock(void)
63 return sched_clock() >> 10;
65 #endif /* CONFIG_DEBUG_PREEMPT */
67 static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
69 return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
72 /* in poll/select we use the global sysctl_net_ll_poll value */
73 static inline unsigned long busy_loop_end_time(void)
75 return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_ll_poll);
78 static inline bool sk_can_busy_loop(struct sock *sk)
80 return sk->sk_ll_usec && sk->sk_napi_id &&
81 !need_resched() && !signal_pending(current);
85 static inline bool busy_loop_timeout(unsigned long end_time)
87 unsigned long now = busy_loop_us_clock();
89 return time_after(now, end_time);
92 /* when used in sock_poll() nonblock is known at compile time to be true
93 * so the loop and end_time will be optimized out
95 static inline bool sk_busy_loop(struct sock *sk, int nonblock)
97 unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
98 const struct net_device_ops *ops;
99 struct napi_struct *napi;
103 * rcu read lock for napi hash
104 * bh so we don't race with net_rx_action
108 napi = napi_by_id(sk->sk_napi_id);
112 ops = napi->dev->netdev_ops;
113 if (!ops->ndo_busy_poll)
117 rc = ops->ndo_busy_poll(napi);
119 if (rc == LL_FLUSH_FAILED)
120 break; /* permanent failure */
123 /* local bh are disabled so it is ok to use _BH */
124 NET_ADD_STATS_BH(sock_net(sk),
125 LINUX_MIB_LOWLATENCYRXPACKETS, rc);
127 } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
128 !need_resched() && !busy_loop_timeout(end_time));
130 rc = !skb_queue_empty(&sk->sk_receive_queue);
132 rcu_read_unlock_bh();
136 /* used in the NIC receive handler to mark the skb */
137 static inline void skb_mark_napi_id(struct sk_buff *skb,
138 struct napi_struct *napi)
140 skb->napi_id = napi->napi_id;
143 /* used in the protocol hanlder to propagate the napi_id to the socket */
144 static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
146 sk->sk_napi_id = skb->napi_id;
149 #else /* CONFIG_NET_LL_RX_POLL */
150 static inline unsigned long net_busy_loop_on(void)
155 static inline unsigned long busy_loop_end_time(void)
160 static inline bool sk_can_busy_loop(struct sock *sk)
165 static inline bool sk_busy_poll(struct sock *sk, int nonblock)
170 static inline void skb_mark_napi_id(struct sk_buff *skb,
171 struct napi_struct *napi)
175 static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
179 static inline bool busy_loop_timeout(unsigned long end_time)
184 #endif /* CONFIG_NET_LL_RX_POLL */
185 #endif /* _LINUX_NET_BUSY_POLL_H */