[deliverable/linux.git] / include / net / ll_poll.h

/*
 * 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>
 */

/*
 * For now this depends on CONFIG_X86_TSC
 */

#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_poll __read_mostly;

/* return values from ndo_ll_poll */
#define LL_FLUSH_FAILED		-1
#define LL_FLUSH_BUSY		-2

/* we don't mind a ~2.5% imprecision */
#define TSC_MHZ (tsc_khz >> 10)

static inline cycles_t ll_end_time(void)
{
	return (cycles_t)TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll)
			+ get_cycles();
}

static inline bool sk_valid_ll(struct sock *sk)
{
	return sysctl_net_ll_poll && sk->sk_napi_id &&
	       !need_resched() && !signal_pending(current);
}

static inline bool can_poll_ll(cycles_t end_time)
{
	return !time_after((unsigned long)get_cycles(),
			    (unsigned long)end_time);
}

static inline bool sk_poll_ll(struct sock *sk, int nonblock)
{
	cycles_t end_time = ll_end_time();
	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 (skb_queue_empty(&sk->sk_receive_queue)
			&& can_poll_ll(end_time) && !nonblock);

	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 cycles_t ll_end_time(void)
{
	return 0;
}

static inline bool sk_valid_ll(struct sock *sk)
{
	return false;
}

static inline bool sk_poll_ll(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 can_poll_ll(cycles_t end_time)
{
	return false;
}

#endif /* CONFIG_NET_LL_RX_POLL */
#endif /* _LINUX_NET_LL_POLL_H */
Commit	Line	Data
06021292 ET	1	/*
	2	* Low Latency Sockets
	3	* Copyright(c) 2013 Intel Corporation.
	4	*
	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.
	8	*
	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
	12	* more details.
	13	*
	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.
	17	*
	18	* Author: Eliezer Tamir
	19	*
	20	* Contact Information:
	21	* e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
	22	*/
	23
	24	/*
	25	* For now this depends on CONFIG_X86_TSC
	26	*/
	27
	28	#ifndef _LINUX_NET_LL_POLL_H
	29	#define _LINUX_NET_LL_POLL_H
	30
	31	#include <linux/netdevice.h>
	32	#include <net/ip.h>
	33
	34	#ifdef CONFIG_NET_LL_RX_POLL
	35
	36	struct napi_struct;
eb6db622	37	extern unsigned int sysctl_net_ll_poll __read_mostly;
06021292 ET	38
	39	/* return values from ndo_ll_poll */
	40	#define LL_FLUSH_FAILED -1
	41	#define LL_FLUSH_BUSY -2
	42
	43	/* we don't mind a ~2.5% imprecision */
	44	#define TSC_MHZ (tsc_khz >> 10)
	45
	46	static inline cycles_t ll_end_time(void)
	47	{
eb6db622 ET	48	return (cycles_t)TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll)
eb6db622 ET	49	+ get_cycles();
06021292 ET	50	}
	51
	52	static inline bool sk_valid_ll(struct sock *sk)
	53	{
	54	return sysctl_net_ll_poll && sk->sk_napi_id &&
	55	!need_resched() && !signal_pending(current);
	56	}
	57
	58	static inline bool can_poll_ll(cycles_t end_time)
	59	{
	60	return !time_after((unsigned long)get_cycles(),
	61	(unsigned long)end_time);
	62	}
	63
	64	static inline bool sk_poll_ll(struct sock *sk, int nonblock)
	65	{
	66	cycles_t end_time = ll_end_time();
	67	const struct net_device_ops *ops;
	68	struct napi_struct *napi;
	69	int rc = false;
	70
	71	/*
	72	* rcu read lock for napi hash
	73	* bh so we don't race with net_rx_action
	74	*/
	75	rcu_read_lock_bh();
	76
	77	napi = napi_by_id(sk->sk_napi_id);
	78	if (!napi)
	79	goto out;
	80
	81	ops = napi->dev->netdev_ops;
	82	if (!ops->ndo_ll_poll)
	83	goto out;
	84
	85	do {
	86
	87	rc = ops->ndo_ll_poll(napi);
	88
	89	if (rc == LL_FLUSH_FAILED)
	90	break; /* permanent failure */
	91
	92	if (rc > 0)
	93	/* local bh are disabled so it is ok to use _BH */
	94	NET_ADD_STATS_BH(sock_net(sk),
	95	LINUX_MIB_LOWLATENCYRXPACKETS, rc);
	96
	97	} while (skb_queue_empty(&sk->sk_receive_queue)
	98	&& can_poll_ll(end_time) && !nonblock);
	99
	100	rc = !skb_queue_empty(&sk->sk_receive_queue);
	101	out:
	102	rcu_read_unlock_bh();
	103	return rc;
	104	}
	105
	106	/* used in the NIC receive handler to mark the skb */
	107	static inline void skb_mark_ll(struct sk_buff skb, struct napi_struct napi)
	108	{
	109	skb->napi_id = napi->napi_id;
	110	}
	111
	112	/* used in the protocol hanlder to propagate the napi_id to the socket */
	113	static inline void sk_mark_ll(struct sock sk, struct sk_buff skb)
114	{
115	sk->sk_napi_id = skb->napi_id;
116	}
117
118	#else /* CONFIG_NET_LL_RX_POLL */
119
120	static inline cycles_t ll_end_time(void)
121	{
122	return 0;
123	}
124
125	static inline bool sk_valid_ll(struct sock *sk)
126	{
127	return false;
128	}
129
130	static inline bool sk_poll_ll(struct sock *sk, int nonblock)
131	{
132	return false;
133	}
134
135	static inline void skb_mark_ll(struct sk_buff skb, struct napi_struct napi)
136	{
137	}
138
139	static inline void sk_mark_ll(struct sock sk, struct sk_buff skb)
140	{
141	}
142
143	static inline bool can_poll_ll(cycles_t end_time)
144	{
145	return false;
146	}
147
148	#endif /* CONFIG_NET_LL_RX_POLL */
149	#endif /* _LINUX_NET_LL_POLL_H */