net: add low latency socket poll (06021292) · Commits · 戴 / test

Documentation/sysctl/net.txt

+7 −0

Original line number	Diff line number	Diff line
		@@ -50,6 +50,13 @@ The maximum number of packets that kernel can handle on a NAPI interrupt,
		it's a Per-CPU variable.
		Default: 64

		low_latency_poll
		----------------
		Low latency busy poll timeout. (needs CONFIG_NET_LL_RX_POLL)
		Approximate time in us to spin waiting for packets on the device queue.
		Recommended value is 50. May increase power usage.
		Default: 0 (off)

		rmem_default
		------------

include/linux/netdevice.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -971,6 +971,9 @@ struct net_device_ops {
		struct netpoll_info *info,
		gfp_t gfp);
		void (ndo_netpoll_cleanup)(struct net_device dev);
		#endif
		#ifdef CONFIG_NET_LL_RX_POLL
		int (ndo_ll_poll)(struct napi_struct dev);
		#endif
		int (ndo_set_vf_mac)(struct net_device dev,
		int queue, u8 *mac);

include/linux/skbuff.h

+6 −2

Original line number	Diff line number	Diff line
		@@ -386,6 +386,7 @@ typedef unsigned char *sk_buff_data_t;
		* @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
		* @dma_cookie: a cookie to one of several possible DMA operations
		* done by skb DMA functions
		* @napi_id: id of the NAPI struct this skb came from
		* @secmark: security marking
		* @mark: Generic packet mark
		* @dropcount: total number of sk_receive_queue overflows
		@@ -500,8 +501,11 @@ struct sk_buff {
		/* 7/9 bit hole (depending on ndisc_nodetype presence) */
		kmemcheck_bitfield_end(flags2);

		#ifdef CONFIG_NET_DMA
		#if defined CONFIG_NET_DMA \|\| defined CONFIG_NET_LL_RX_POLL
		union {
		unsigned int napi_id;
		dma_cookie_t dma_cookie;
		};
		#endif
		#ifdef CONFIG_NETWORK_SECMARK
		__u32 secmark;

include/net/ll_poll.h

0 → 100644

+148 −0

Original line number	Diff line number	Diff line
		/*
		* 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 long 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 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 */

include/net/sock.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -229,6 +229,7 @@ struct cg_proto;
		* @sk_omem_alloc: "o" is "option" or "other"
		* @sk_wmem_queued: persistent queue size
		* @sk_forward_alloc: space allocated forward
		* @sk_napi_id: id of the last napi context to receive data for sk
		* @sk_allocation: allocation mode
		* @sk_sndbuf: size of send buffer in bytes
		* @sk_flags: %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE,
		@@ -324,6 +325,9 @@ struct sock {
		int sk_forward_alloc;
		#ifdef CONFIG_RPS
		__u32 sk_rxhash;
		#endif
		#ifdef CONFIG_NET_LL_RX_POLL
		unsigned int sk_napi_id;
		#endif
		atomic_t sk_drops;
		int sk_rcvbuf;

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