[PATCH v7 net-next 0/5] net: low latency Ethernet device polling

[PATCH v7 net-next 0/5] net: low latency Ethernet device polling

[Eliezer Tamir]

more fixes.
Thank you all for your input.

-Eliezer

change log:
v7
- suggested by Ben Hutchings and Eric Dumazet:
  type fixes, static for globals in net/core.c,
  avoid napi_id collisions in napi_hash_add()

v6
- many small fixes suggested by Eric Dumazet:
  data locality, typos, documentation
  protect napi_hash insert/delete with a spinlock (napi_gen_id is no
  longer atomic_t since it's only accessed with the spinlock held.)
- added IPv6 TCP and UDP support (only minimally tested)

v5
- corrections suggested by Ben Hutchings:
  fixed typos, moved the config option and sysctl value from IPv4 to net
- moved sk_mark_ll() to the protocol handlers
- removed global id mechanism, replaced with a hashed napi_id.
  based on code sample from Eric Dumazet
  Note that ixgbe_free_q_vector() already waits an rcu grace period
  before freeing the q_vector, so nothing additional needs to be done
  when adding a call to napi_hash_del().
- simple poll/select support

v4
- removed separate config option for TCP as suggested Eric Dumazet.
- added linux mib counter for packets received through the low latency path,
  as suggested by Andi Kleen.
- re-allow module unloading, remove module param, use a global generation id
  instead to prevent the use of a stale napi pointer, as suggested
  by Eric Dumazet
- updated Documentation/networking/ip-sysctl.txt text

v3
- coding style changes suggested by Dave Miller

v2
- the sysctl knob is now in microseconds. The default value is now 0 (off).
- for now the code depends at configure time on CONFIG_I86_TSC 
- the napi reference in struct skb is now a union with the dma cookie
  since the former is only used on RX and the latter on TX,
  as suggested by Eric Dumazet.
- we do a better job at honoring non-blocking operations.
- removed busy-polling support for tcp_read_sock()
- remove dynamic disabling of GRO
- coding style fixes
- disallow unloading the device module after the feature has been used

Credit:
Jesse Brandeburg, Arun Chekhov Ilango, Julie Cummings,
Alexander Duyck, Eric Geisler, Jason Neighbors, Yadong Li,
Mike Polehn, Anil Vasudevan, Don Wood
Special thanks for finding bugs in earlier versions:
Willem de Bruijn and Andi Kleen

[PATCH v7 net-next 1/5] net: add napi_id and hash

[Eliezer Tamir]

Adds a napi_id and a hashing mechanism to lookup a napi by id.
This will be used by subsequent patches to implement low latency
Ethernet device polling.
Based on a code sample by Eric Dumazet.

Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

 include/linux/netdevice.h |   29 ++++++++++++++++++++++
 net/core/dev.c            |   59 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 0 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 8f967e3..39bbd46 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -324,12 +324,15 @@ struct napi_struct {
 	struct sk_buff		*gro_list;
 	struct sk_buff		*skb;
 	struct list_head	dev_list;
+	struct hlist_node	napi_hash_node;
+	unsigned int		napi_id;
 };
 
 enum {
 	NAPI_STATE_SCHED,	/* Poll is scheduled */
 	NAPI_STATE_DISABLE,	/* Disable pending */
 	NAPI_STATE_NPSVC,	/* Netpoll - don't dequeue from poll_list */
+	NAPI_STATE_HASHED,	/* In NAPI hash */
 };
 
 enum gro_result {
@@ -446,6 +449,32 @@ extern void __napi_complete(struct napi_struct *n);
 extern void napi_complete(struct napi_struct *n);
 
 /**
+ *	napi_by_id - lookup a NAPI by napi_id
+ *	@napi_id: hashed napi_id
+ *
+ * lookup @napi_id in napi_hash table
+ * must be called under rcu_read_lock()
+ */
+extern struct napi_struct *napi_by_id(unsigned int napi_id);
+
+/**
+ *	napi_hash_add - add a NAPI to global hashtable
+ *	@napi: napi context
+ *
+ * generate a new napi_id and store a @napi under it in napi_hash
+ */
+extern void napi_hash_add(struct napi_struct *napi);
+
+/**
+ *	napi_hash_del - remove a NAPI from global table
+ *	@napi: napi context
+ *
+ * Warning: caller must observe rcu grace period
+ * before freeing memory containing @napi
+ */
+extern void napi_hash_del(struct napi_struct *napi);
+
+/**
  *	napi_disable - prevent NAPI from scheduling
  *	@n: napi context
  *
diff --git a/net/core/dev.c b/net/core/dev.c
index d4d874a..f8388a0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -129,6 +129,7 @@
 #include <linux/inetdevice.h>
 #include <linux/cpu_rmap.h>
 #include <linux/static_key.h>
+#include <linux/hashtable.h>
 
 #include "net-sysfs.h"
 
@@ -166,6 +167,12 @@ static struct list_head offload_base __read_mostly;
 DEFINE_RWLOCK(dev_base_lock);
 EXPORT_SYMBOL(dev_base_lock);
 
+/* protects napi_hash addition/deletion and napi_gen_id */
+static DEFINE_SPINLOCK(napi_hash_lock);
+
+static unsigned int napi_gen_id;
+static DEFINE_HASHTABLE(napi_hash, 8);
+
 seqcount_t devnet_rename_seq;
 
 static inline void dev_base_seq_inc(struct net *net)
@@ -4136,6 +4143,58 @@ void napi_complete(struct napi_struct *n)
 }
 EXPORT_SYMBOL(napi_complete);
 
+/* must be called under rcu_read_lock(), as we dont take a reference */
+struct napi_struct *napi_by_id(unsigned int napi_id)
+{
+	unsigned int hash = napi_id % HASH_SIZE(napi_hash);
+	struct napi_struct *napi;
+
+	hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node)
+		if (napi->napi_id == napi_id)
+			return napi;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(napi_by_id);
+
+void napi_hash_add(struct napi_struct *napi)
+{
+	if (!test_and_set_bit(NAPI_STATE_HASHED, &napi->state)) {
+
+		spin_lock(&napi_hash_lock);
+
+		/* 0 is not a valid id, we also skip an id that is taken
+		 * we expect both events to be extremely rare
+		 */
+		napi->napi_id = 0;
+		while (!napi->napi_id) {
+			napi->napi_id = ++napi_gen_id;
+			if (napi_by_id(napi->napi_id))
+				napi->napi_id = 0;
+		}
+
+		hlist_add_head_rcu(&napi->napi_hash_node,
+			&napi_hash[napi->napi_id % HASH_SIZE(napi_hash)]);
+
+		spin_unlock(&napi_hash_lock);
+	}
+}
+EXPORT_SYMBOL_GPL(napi_hash_add);
+
+/* Warning : caller is responsible to make sure rcu grace period
+ * is respected before freeing memory containing @napi
+ */
+void napi_hash_del(struct napi_struct *napi)
+{
+	spin_lock(&napi_hash_lock);
+
+	if (test_and_clear_bit(NAPI_STATE_HASHED, &napi->state))
+		hlist_del_rcu(&napi->napi_hash_node);
+
+	spin_unlock(&napi_hash_lock);
+}
+EXPORT_SYMBOL_GPL(napi_hash_del);
+
 void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
 		    int (*poll)(struct napi_struct *, int), int weight)
 {


------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

[PATCH v7 net-next 2/5] net: implement support for low latency socket polling

[Eliezer Tamir]

Adds a new ndo_ll_poll method and the code that supports and uses it.
This method can be used by low latency applications to busy poll Ethernet
device queues directly from the socket code. The value of sysctl_net_ll_poll
controls how many microseconds to poll. Set to zero to disable.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

 Documentation/sysctl/net.txt |    7 ++
 fs/select.c                  |    7 ++
 include/linux/netdevice.h    |    3 +
 include/linux/skbuff.h       |    8 ++
 include/net/ll_poll.h        |  148 ++++++++++++++++++++++++++++++++++++++++++
 include/net/sock.h           |    4 +
 include/uapi/linux/snmp.h    |    1 
 net/Kconfig                  |   12 +++
 net/core/datagram.c          |    4 +
 net/core/skbuff.c            |    4 +
 net/core/sock.c              |    6 ++
 net/core/sysctl_net_core.c   |   10 +++
 net/ipv4/proc.c              |    1 
 net/ipv4/udp.c               |    6 +-
 net/ipv6/udp.c               |    6 +-
 net/socket.c                 |   16 ++++-
 16 files changed, 238 insertions(+), 5 deletions(-)
 create mode 100644 include/net/ll_poll.h

diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt
index c1f8640..85ab72d 100644
--- a/Documentation/sysctl/net.txt
+++ b/Documentation/sysctl/net.txt
@@ -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
 ------------
 
diff --git a/fs/select.c b/fs/select.c
index 8c1c96c..f116bf0 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -27,6 +27,7 @@
 #include <linux/rcupdate.h>
 #include <linux/hrtimer.h>
 #include <linux/sched/rt.h>
+#include <net/ll_poll.h>
 
 #include <asm/uaccess.h>
 
@@ -400,6 +401,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
 	poll_table *wait;
 	int retval, i, timed_out = 0;
 	unsigned long slack = 0;
+	cycles_t ll_time = ll_end_time();
 
 	rcu_read_lock();
 	retval = max_select_fd(n, fds);
@@ -486,6 +488,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
 			break;
 		}
 
+		if (can_poll_ll(ll_time))
+			continue;
 		/*
 		 * If this is the first loop and we have a timeout
 		 * given, then we convert to ktime_t and set the to
@@ -750,6 +754,7 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
 	ktime_t expire, *to = NULL;
 	int timed_out = 0, count = 0;
 	unsigned long slack = 0;
+	cycles_t ll_time = ll_end_time();
 
 	/* Optimise the no-wait case */
 	if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
@@ -795,6 +800,8 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
 		if (count || timed_out)
 			break;
 
+		if (can_poll_ll(ll_time))
+			continue;
 		/*
 		 * If this is the first loop and we have a timeout
 		 * given, then we convert to ktime_t and set the to
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 39bbd46..2ecb96d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -972,6 +972,9 @@ struct net_device_ops {
 						     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);
 	int			(*ndo_set_vf_vlan)(struct net_device *dev,
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 5f93119..86dfc3d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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
-	dma_cookie_t		dma_cookie;
+#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;
diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
new file mode 100644
index 0000000..949e139
--- /dev/null
+++ b/include/net/ll_poll.h
@@ -0,0 +1,148 @@
+/*
+ * 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 hander 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 0;
+}
+
+static inline bool sk_poll_ll(struct sock *sk, int nonblock)
+{
+	return 0;
+}
+
+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(unsigned long end_time)
+{
+	return false;
+}
+
+#endif /* CONFIG_NET_LL_RX_POLL */
+#endif /* _LINUX_NET_LL_POLL_H */
diff --git a/include/net/sock.h b/include/net/sock.h
index 66772cf..ac8e181 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -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,
@@ -325,6 +326,9 @@ struct sock {
 #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;
 
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index df2e8b4..26cbf76 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -253,6 +253,7 @@ enum
 	LINUX_MIB_TCPFASTOPENLISTENOVERFLOW,	/* TCPFastOpenListenOverflow */
 	LINUX_MIB_TCPFASTOPENCOOKIEREQD,	/* TCPFastOpenCookieReqd */
 	LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES, /* TCPSpuriousRtxHostQueues */
+	LINUX_MIB_LOWLATENCYRXPACKETS,		/* LowLatencyRxPackets */
 	__LINUX_MIB_MAX
 };
 
diff --git a/net/Kconfig b/net/Kconfig
index 523e43e..d6a9ce6 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -243,6 +243,18 @@ config NETPRIO_CGROUP
 	  Cgroup subsystem for use in assigning processes to network priorities on
 	  a per-interface basis
 
+config NET_LL_RX_POLL
+	bool "Low Latency Receive Poll"
+	depends on X86_TSC
+	default n
+	---help---
+	  Support Low Latency Receive Queue Poll.
+	  (For network card drivers which support this option.)
+	  When waiting for data in read or poll call directly into the the device driver
+	  to flush packets which may be pending on the device queues into the stack.
+
+	  If unsure, say N.
+
 config BQL
 	boolean
 	depends on SYSFS
diff --git a/net/core/datagram.c b/net/core/datagram.c
index b71423d..9cbaba9 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -56,6 +56,7 @@
 #include <net/sock.h>
 #include <net/tcp_states.h>
 #include <trace/events/skb.h>
+#include <net/ll_poll.h>
 
 /*
  *	Is a socket 'connection oriented' ?
@@ -207,6 +208,9 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 		}
 		spin_unlock_irqrestore(&queue->lock, cpu_flags);
 
+		if (sk_valid_ll(sk) && sk_poll_ll(sk, flags & MSG_DONTWAIT))
+			continue;
+
 		/* User doesn't want to wait */
 		error = -EAGAIN;
 		if (!timeo)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f45de07..674bcde 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -739,6 +739,10 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	new->vlan_tci		= old->vlan_tci;
 
 	skb_copy_secmark(new, old);
+
+#ifdef CONFIG_NET_LL_RX_POLL
+	new->napi_id	= old->napi_id;
+#endif
 }
 
 /*
diff --git a/net/core/sock.c b/net/core/sock.c
index 6ba327d..804fd5b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -139,6 +139,8 @@
 #include <net/tcp.h>
 #endif
 
+#include <net/ll_poll.h>
+
 static DEFINE_MUTEX(proto_list_mutex);
 static LIST_HEAD(proto_list);
 
@@ -2284,6 +2286,10 @@ void sock_init_data(struct socket *sock, struct sock *sk)
 
 	sk->sk_stamp = ktime_set(-1L, 0);
 
+#ifdef CONFIG_NET_LL_RX_POLL
+	sk->sk_napi_id		=	0;
+#endif
+
 	/*
 	 * Before updating sk_refcnt, we must commit prior changes to memory
 	 * (Documentation/RCU/rculist_nulls.txt for details)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 741db5fc..ae98c95 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -19,6 +19,7 @@
 #include <net/ip.h>
 #include <net/sock.h>
 #include <net/net_ratelimit.h>
+#include <net/ll_poll.h>
 
 static int one = 1;
 
@@ -284,6 +285,15 @@ static struct ctl_table net_core_table[] = {
 		.proc_handler	= flow_limit_table_len_sysctl
 	},
 #endif /* CONFIG_NET_FLOW_LIMIT */
+#ifdef CONFIG_NET_LL_RX_POLL
+	{
+		.procname	= "low_latency_poll",
+		.data		= &sysctl_net_ll_poll,
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec
+	},
+#endif
 #endif /* CONFIG_NET */
 	{
 		.procname	= "netdev_budget",
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 2a5bf86..6577a11 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -273,6 +273,7 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TCPFastOpenListenOverflow", LINUX_MIB_TCPFASTOPENLISTENOVERFLOW),
 	SNMP_MIB_ITEM("TCPFastOpenCookieReqd", LINUX_MIB_TCPFASTOPENCOOKIEREQD),
 	SNMP_MIB_ITEM("TCPSpuriousRtxHostQueues", LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES),
+	SNMP_MIB_ITEM("LowLatencyRxPackets", LINUX_MIB_LOWLATENCYRXPACKETS),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index aa5eff4..e7ab9c8 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -109,6 +109,7 @@
 #include <trace/events/udp.h>
 #include <linux/static_key.h>
 #include <trace/events/skb.h>
+#include <net/ll_poll.h>
 #include "udp_impl.h"
 
 struct udp_table udp_table __read_mostly;
@@ -1709,7 +1710,10 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 
 	if (sk != NULL) {
-		int ret = udp_queue_rcv_skb(sk, skb);
+		int ret;
+
+		sk_mark_ll(sk, skb);
+		ret = udp_queue_rcv_skb(sk, skb);
 		sock_put(sk);
 
 		/* a return value > 0 means to resubmit the input, but
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 42923b1..4035997 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -46,6 +46,7 @@
 #include <net/ip6_checksum.h>
 #include <net/xfrm.h>
 #include <net/inet6_hashtables.h>
+#include <net/ll_poll.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -841,7 +842,10 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	 */
 	sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 	if (sk != NULL) {
-		int ret = udpv6_queue_rcv_skb(sk, skb);
+		int ret;
+
+		sk_mark_ll(sk, skb);
+		ret = udpv6_queue_rcv_skb(sk, skb);
 		sock_put(sk);
 
 		/* a return value > 0 means to resubmit the input, but
diff --git a/net/socket.c b/net/socket.c
index 6b94633..02d0e15 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -104,6 +104,12 @@
 #include <linux/route.h>
 #include <linux/sockios.h>
 #include <linux/atalk.h>
+#include <net/ll_poll.h>
+
+#ifdef CONFIG_NET_LL_RX_POLL
+unsigned long sysctl_net_ll_poll __read_mostly;
+EXPORT_SYMBOL_GPL(sysctl_net_ll_poll);
+#endif
 
 static int sock_no_open(struct inode *irrelevant, struct file *dontcare);
 static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
@@ -1142,13 +1148,21 @@ EXPORT_SYMBOL(sock_create_lite);
 /* No kernel lock held - perfect */
 static unsigned int sock_poll(struct file *file, poll_table *wait)
 {
+	unsigned int poll_result;
 	struct socket *sock;
 
 	/*
 	 *      We can't return errors to poll, so it's either yes or no.
 	 */
 	sock = file->private_data;
-	return sock->ops->poll(file, sock, wait);
+
+	poll_result = sock->ops->poll(file, sock, wait);
+
+	if (!(poll_result & (POLLRDNORM | POLLERR | POLLRDHUP | POLLHUP)) &&
+		sk_valid_ll(sock->sk) && sk_poll_ll(sock->sk, 1))
+			poll_result = sock->ops->poll(file, sock, NULL);
+
+	return poll_result;
 }
 
 static int sock_mmap(struct file *file, struct vm_area_struct *vma)


------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

Re: [PATCH v7 net-next 2/5] net: implement support for low latency socket polling

[Amir Vadai]

On 30/05/2013 14:41, Eliezer Tamir wrote:
> diff --git a/fs/select.c b/fs/select.c
> index 8c1c96c..f116bf0 100644
> --- a/fs/select.c
> +++ b/fs/select.c
> @@ -27,6 +27,7 @@
>  #include <linux/rcupdate.h>
>  #include <linux/hrtimer.h>
>  #include <linux/sched/rt.h>
> +#include <net/ll_poll.h>
>  
>  #include <asm/uaccess.h>
>  
> @@ -400,6 +401,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
>  	poll_table *wait;
>  	int retval, i, timed_out = 0;
>  	unsigned long slack = 0;
> +	cycles_t ll_time = ll_end_time();
>  
>  	rcu_read_lock();
>  	retval = max_select_fd(n, fds);
> @@ -486,6 +488,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
>  			break;
>  		}
>  
> +		if (can_poll_ll(ll_time))
> +			continue;
I don't see here discrimination between sockets that you want to poll
and other sockets.
So it means that select will busy poll every type of file descriptor
instead of going to sleep.
Should have a condition with something like sk_valid_ll()

>  		/*
>  		 * If this is the first loop and we have a timeout
>  		 * given, then we convert to ktime_t and set the to


...

> +static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
> +{
> +}
> +
> +static inline bool can_poll_ll(unsigned long end_time)
should use here cycles_t too.

> +{
> +	return false;
> +}
> +
> +#endif /* CONFIG_NET_LL_RX_POLL */
> +#endif /* _LINUX_NET_LL_POLL_H */


Also, something general about this patch. I think you should split out
to separate patches all the users of the feature, like you did for TCP.
I would suggest small patches for UDP, select and poll.

Thanks,
Amir

Re: [PATCH v7 net-next 2/5] net: implement support for low latency socket polling

[Eliezer Tamir]

On 30/05/2013 18:07, Amir Vadai wrote:
> On 30/05/2013 14:41, Eliezer Tamir wrote:
>> diff --git a/fs/select.c b/fs/select.c
>> @@ -486,6 +488,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
>>   			break;
>>   		}
>>
>> +		if (can_poll_ll(ll_time))
>> +			continue;
> I don't see here discrimination between sockets that you want to poll
> and other sockets.
> So it means that select will busy poll every type of file descriptor
> instead of going to sleep.
> Should have a condition with something like sk_valid_ll()

As I said earlier, select and poll are far from complete.
We are working on this.
Right now when you turn this on, all sockets get the same treatment.
sk_valid_ll() can't work here, because we don't have a single socket to 
work with.

At the moment, I think the right way to solve this might be to add
new flags to poll.h So that select/poll can signal to sock_poll
that it wants to busy-wait and sock_poll can tell select/poll that
it has found a socket that can support it.

Remember that the information is dynamic so we can't know in advance
which sockets can busy-poll.

If anyone else has a suggestion I would really like to hear it.

>
>> +static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
>> +{
>> +}
>> +
>> +static inline bool can_poll_ll(unsigned long end_time)
> should use here cycles_t too.

yes

>
>> +{
>> +	return false;
>> +}
>> +
>> +#endif /* CONFIG_NET_LL_RX_POLL */
>> +#endif /* _LINUX_NET_LL_POLL_H */
>
>
> Also, something general about this patch. I think you should split out
> to separate patches all the users of the feature, like you did for TCP.
> I would suggest small patches for UDP, select and poll.

Splitting out the users of the features as you call it will only move 
out about 30 lines of patch, I think it will make reviewing harder since 
you will not be able to see the whole picture in one patch.
But if anyone else thinks this is a good idea, I will do it.

-Eliezer

------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

[PATCH v7 net-next 3/5] tcp: add TCP support for low latency receive poll.

[Eliezer Tamir]

Adds busy-poll support for TCP.
Copy the napi_id from an incomming skb to the sk in tcp_v[46]_rcv().
when there is no data in the socket we busy-poll in tcp_recvmsg().
This is a good example of how to add busy-poll support to new protocols.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

 net/ipv4/tcp.c      |    5 +++++
 net/ipv4/tcp_ipv4.c |    2 ++
 net/ipv6/tcp_ipv6.c |    2 ++
 3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1f58594..685a3ea 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -279,6 +279,7 @@
 
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
+#include <net/ll_poll.h>
 
 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
 
@@ -1551,6 +1552,10 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	struct sk_buff *skb;
 	u32 urg_hole = 0;
 
+	if (sk_valid_ll(sk) && skb_queue_empty(&sk->sk_receive_queue)
+	    && (sk->sk_state == TCP_ESTABLISHED))
+		sk_poll_ll(sk, nonblock);
+
 	lock_sock(sk);
 
 	err = -ENOTCONN;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d20ede0..35fd8bc 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -75,6 +75,7 @@
 #include <net/netdma.h>
 #include <net/secure_seq.h>
 #include <net/tcp_memcontrol.h>
+#include <net/ll_poll.h>
 
 #include <linux/inet.h>
 #include <linux/ipv6.h>
@@ -2011,6 +2012,7 @@ process:
 	if (sk_filter(sk, skb))
 		goto discard_and_relse;
 
+	sk_mark_ll(sk, skb);
 	skb->dev = NULL;
 
 	bh_lock_sock_nested(sk);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0a17ed9..5cffa5c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -63,6 +63,7 @@
 #include <net/inet_common.h>
 #include <net/secure_seq.h>
 #include <net/tcp_memcontrol.h>
+#include <net/ll_poll.h>
 
 #include <asm/uaccess.h>
 
@@ -1498,6 +1499,7 @@ process:
 	if (sk_filter(sk, skb))
 		goto discard_and_relse;
 
+	sk_mark_ll(sk, skb);
 	skb->dev = NULL;
 
 	bh_lock_sock_nested(sk);


------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

[PATCH v7 net-next 4/5] ixgbe: Add support for ndo_ll_poll

[Eliezer Tamir]

Add the ixgbe driver code implementing ndo_ll_poll.
Adds ndo_ll_poll method and locking between it and the napi poll.
When receiving a packet we use skb_mark_ll to record the napi it came from.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

 drivers/net/ethernet/intel/ixgbe/ixgbe.h      |  120 +++++++++++++++++++++++++
 drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c  |    2 
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |   63 +++++++++++--
 3 files changed, 177 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index ca93238..04fdbf6 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -52,6 +52,8 @@
 #include <linux/dca.h>
 #endif
 
+#include <net/ll_poll.h>
+
 /* common prefix used by pr_<> macros */
 #undef pr_fmt
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -356,9 +358,127 @@ struct ixgbe_q_vector {
 	struct rcu_head rcu;	/* to avoid race with update stats on free */
 	char name[IFNAMSIZ + 9];
 
+#ifdef CONFIG_NET_LL_RX_POLL
+	unsigned int state;
+#define IXGBE_QV_STATE_IDLE        0
+#define IXGBE_QV_STATE_NAPI	   1    /* NAPI owns this QV */
+#define IXGBE_QV_STATE_POLL	   2    /* poll owns this QV */
+#define IXGBE_QV_LOCKED (IXGBE_QV_STATE_NAPI | IXGBE_QV_STATE_POLL)
+#define IXGBE_QV_STATE_NAPI_YIELD  4    /* NAPI yielded this QV */
+#define IXGBE_QV_STATE_POLL_YIELD  8    /* poll yielded this QV */
+#define IXGBE_QV_YIELD (IXGBE_QV_STATE_NAPI_YIELD | IXGBE_QV_STATE_POLL_YIELD)
+#define IXGBE_QV_USER_PEND (IXGBE_QV_STATE_POLL | IXGBE_QV_STATE_POLL_YIELD)
+	spinlock_t lock;
+#endif  /* CONFIG_NET_LL_RX_POLL */
+
 	/* for dynamic allocation of rings associated with this q_vector */
 	struct ixgbe_ring ring[0] ____cacheline_internodealigned_in_smp;
 };
+#ifdef CONFIG_NET_LL_RX_POLL
+static inline void ixgbe_qv_init_lock(struct ixgbe_q_vector *q_vector)
+{
+
+	spin_lock_init(&q_vector->lock);
+	q_vector->state = IXGBE_QV_STATE_IDLE;
+}
+
+/* called from the device poll rutine to get ownership of a q_vector */
+static inline int ixgbe_qv_lock_napi(struct ixgbe_q_vector *q_vector)
+{
+	int rc = true;
+	spin_lock(&q_vector->lock);
+	if (q_vector->state & IXGBE_QV_LOCKED) {
+		WARN_ON(q_vector->state & IXGBE_QV_STATE_NAPI);
+		q_vector->state |= IXGBE_QV_STATE_NAPI_YIELD;
+		rc = false;
+	} else
+		/* we don't care if someone yielded */
+		q_vector->state = IXGBE_QV_STATE_NAPI;
+	spin_unlock(&q_vector->lock);
+	return rc;
+}
+
+/* returns true is someone tried to get the qv while napi had it */
+static inline int ixgbe_qv_unlock_napi(struct ixgbe_q_vector *q_vector)
+{
+	int rc = false;
+	spin_lock(&q_vector->lock);
+	WARN_ON(q_vector->state & (IXGBE_QV_STATE_POLL |
+			       IXGBE_QV_STATE_NAPI_YIELD));
+
+	if (q_vector->state & IXGBE_QV_STATE_POLL_YIELD)
+		rc = true;
+	q_vector->state = IXGBE_QV_STATE_IDLE;
+	spin_unlock(&q_vector->lock);
+	return rc;
+}
+
+/* called from ixgbe_low_latency_poll() */
+static inline int ixgbe_qv_lock_poll(struct ixgbe_q_vector *q_vector)
+{
+	int rc = true;
+	spin_lock_bh(&q_vector->lock);
+	if ((q_vector->state & IXGBE_QV_LOCKED)) {
+		q_vector->state |= IXGBE_QV_STATE_POLL_YIELD;
+		rc = false;
+	} else
+		/* preserve yield marks */
+		q_vector->state |= IXGBE_QV_STATE_POLL;
+	spin_unlock_bh(&q_vector->lock);
+	return rc;
+}
+
+/* returns true if someone tried to get the qv while it was locked */
+static inline int ixgbe_qv_unlock_poll(struct ixgbe_q_vector *q_vector)
+{
+	int rc = false;
+	spin_lock_bh(&q_vector->lock);
+	WARN_ON(q_vector->state & (IXGBE_QV_STATE_NAPI));
+
+	if (q_vector->state & IXGBE_QV_STATE_POLL_YIELD)
+		rc = true;
+	q_vector->state = IXGBE_QV_STATE_IDLE;
+	spin_unlock_bh(&q_vector->lock);
+	return rc;
+}
+
+/* true if a socket is polling, even if it did not get the lock */
+static inline int ixgbe_qv_ll_polling(struct ixgbe_q_vector *q_vector)
+{
+	WARN_ON(!(q_vector->state & IXGBE_QV_LOCKED));
+	return q_vector->state & IXGBE_QV_USER_PEND;
+}
+#else /* CONFIG_NET_LL_RX_POLL */
+static inline void ixgbe_qv_init_lock(struct ixgbe_q_vector *q_vector)
+{
+}
+
+static inline int ixgbe_qv_lock_napi(struct ixgbe_q_vector *q_vector)
+{
+	return true;
+}
+
+static inline int ixgbe_qv_unlock_napi(struct ixgbe_q_vector *q_vector)
+{
+	return false;
+}
+
+static inline int ixgbe_qv_lock_poll(struct ixgbe_q_vector *q_vector)
+{
+	return false;
+}
+
+static inline int ixgbe_qv_unlock_poll(struct ixgbe_q_vector *q_vector)
+{
+	return false;
+}
+
+static inline int ixgbe_qv_ll_polling(struct ixgbe_q_vector *q_vector)
+{
+	return false;
+}
+#endif /* CONFIG_NET_LL_RX_POLL */
+
 #ifdef CONFIG_IXGBE_HWMON
 
 #define IXGBE_HWMON_TYPE_LOC		0
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
index ef5f7a6..90b4e10 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
@@ -811,6 +811,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
 	/* initialize NAPI */
 	netif_napi_add(adapter->netdev, &q_vector->napi,
 		       ixgbe_poll, 64);
+	napi_hash_add(&q_vector->napi);
 
 	/* tie q_vector and adapter together */
 	adapter->q_vector[v_idx] = q_vector;
@@ -931,6 +932,7 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
 		adapter->rx_ring[ring->queue_index] = NULL;
 
 	adapter->q_vector[v_idx] = NULL;
+	napi_hash_del(&q_vector->napi);
 	netif_napi_del(&q_vector->napi);
 
 	/*
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index d30fbdd..9a7dc40 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1504,7 +1504,9 @@ static void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
 {
 	struct ixgbe_adapter *adapter = q_vector->adapter;
 
-	if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
+	if (ixgbe_qv_ll_polling(q_vector))
+		netif_receive_skb(skb);
+	else if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
 		napi_gro_receive(&q_vector->napi, skb);
 	else
 		netif_rx(skb);
@@ -1892,9 +1894,9 @@ dma_sync:
  * expensive overhead for IOMMU access this provides a means of avoiding
  * it by maintaining the mapping of the page to the syste.
  *
- * Returns true if all work is completed without reaching budget
+ * Returns amount of work completed
  **/
-static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
+static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 			       struct ixgbe_ring *rx_ring,
 			       const int budget)
 {
@@ -1976,6 +1978,7 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 		}
 
 #endif /* IXGBE_FCOE */
+		skb_mark_ll(skb, &q_vector->napi);
 		ixgbe_rx_skb(q_vector, skb);
 
 		/* update budget accounting */
@@ -1992,9 +1995,37 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 	if (cleaned_count)
 		ixgbe_alloc_rx_buffers(rx_ring, cleaned_count);
 
-	return (total_rx_packets < budget);
+	return total_rx_packets;
 }
 
+#ifdef CONFIG_NET_LL_RX_POLL
+/* must be called with local_bh_disable()d */
+static int ixgbe_low_latency_recv(struct napi_struct *napi)
+{
+	struct ixgbe_q_vector *q_vector =
+			container_of(napi, struct ixgbe_q_vector, napi);
+	struct ixgbe_adapter *adapter = q_vector->adapter;
+	struct ixgbe_ring  *ring;
+	int found = 0;
+
+	if (test_bit(__IXGBE_DOWN, &adapter->state))
+		return LL_FLUSH_FAILED;
+
+	if (!ixgbe_qv_lock_poll(q_vector))
+		return LL_FLUSH_BUSY;
+
+	ixgbe_for_each_ring(ring, q_vector->rx) {
+		found = ixgbe_clean_rx_irq(q_vector, ring, 4);
+		if (found)
+			break;
+	}
+
+	ixgbe_qv_unlock_poll(q_vector);
+
+	return found;
+}
+#endif	/* CONFIG_NET_LL_RX_POLL */
+
 /**
  * ixgbe_configure_msix - Configure MSI-X hardware
  * @adapter: board private structure
@@ -2550,6 +2581,9 @@ int ixgbe_poll(struct napi_struct *napi, int budget)
 	ixgbe_for_each_ring(ring, q_vector->tx)
 		clean_complete &= !!ixgbe_clean_tx_irq(q_vector, ring);
 
+	if (!ixgbe_qv_lock_napi(q_vector))
+		return budget;
+
 	/* attempt to distribute budget to each queue fairly, but don't allow
 	 * the budget to go below 1 because we'll exit polling */
 	if (q_vector->rx.count > 1)
@@ -2558,9 +2592,10 @@ int ixgbe_poll(struct napi_struct *napi, int budget)
 		per_ring_budget = budget;
 
 	ixgbe_for_each_ring(ring, q_vector->rx)
-		clean_complete &= ixgbe_clean_rx_irq(q_vector, ring,
-						     per_ring_budget);
+		clean_complete &= (ixgbe_clean_rx_irq(q_vector, ring,
+				   per_ring_budget) < per_ring_budget);
 
+	ixgbe_qv_unlock_napi(q_vector);
 	/* If all work not completed, return budget and keep polling */
 	if (!clean_complete)
 		return budget;
@@ -3747,16 +3782,25 @@ static void ixgbe_napi_enable_all(struct ixgbe_adapter *adapter)
 {
 	int q_idx;
 
-	for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++)
+	for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++) {
+		ixgbe_qv_init_lock(adapter->q_vector[q_idx]);
 		napi_enable(&adapter->q_vector[q_idx]->napi);
+	}
 }
 
 static void ixgbe_napi_disable_all(struct ixgbe_adapter *adapter)
 {
 	int q_idx;
 
-	for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++)
+	local_bh_disable(); /* for ixgbe_qv_lock_napi() */
+	for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++) {
 		napi_disable(&adapter->q_vector[q_idx]->napi);
+		while (!ixgbe_qv_lock_napi(adapter->q_vector[q_idx])) {
+			pr_info("QV %d locked\n", q_idx);
+			mdelay(1);
+		}
+	}
+	local_bh_enable();
 }
 
 #ifdef CONFIG_IXGBE_DCB
@@ -7177,6 +7221,9 @@ static const struct net_device_ops ixgbe_netdev_ops = {
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	.ndo_poll_controller	= ixgbe_netpoll,
 #endif
+#ifdef CONFIG_NET_LL_RX_POLL
+	.ndo_ll_poll		= ixgbe_low_latency_recv,
+#endif
 #ifdef IXGBE_FCOE
 	.ndo_fcoe_ddp_setup = ixgbe_fcoe_ddp_get,
 	.ndo_fcoe_ddp_target = ixgbe_fcoe_ddp_target,


------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

Re: [PATCH v7 net-next 4/5] ixgbe: Add support for ndo_ll_poll

[Cong Wang]

On Thu, May 30, 2013 at 7:41 PM, Eliezer Tamir
<eliezer.tamir@linux.intel.com> wrote:
....
> +#else /* CONFIG_NET_LL_RX_POLL */
> +static inline void ixgbe_qv_init_lock(struct ixgbe_q_vector *q_vector)
> +{
> +}
> +
> +static inline int ixgbe_qv_lock_napi(struct ixgbe_q_vector *q_vector)
> +{
> +       return true;
> +}
> +
> +static inline int ixgbe_qv_unlock_napi(struct ixgbe_q_vector *q_vector)
> +{
> +       return false;
> +}
> +
> +static inline int ixgbe_qv_lock_poll(struct ixgbe_q_vector *q_vector)
> +{
> +       return false;
> +}
> +
> +static inline int ixgbe_qv_unlock_poll(struct ixgbe_q_vector *q_vector)
> +{
> +       return false;
> +}
> +
> +static inline int ixgbe_qv_ll_polling(struct ixgbe_q_vector *q_vector)
> +{
> +       return false;
> +}


Then please make them bool.

------------------------------------------------------------------------------
Get 100% visibility into Java/.NET code with AppDynamics Lite
It's a free troubleshooting tool designed for production
Get down to code-level detail for bottlenecks, with <2% overhead.
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap2
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

[PATCH v7 net-next 5/5] ixgbe: add extra stats for ndo_ll_poll

[Eliezer Tamir]

Add additional statistics to the ixgbe driver for ndo_ll_poll
Defined under LL_EXTENDED_STATS

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

 drivers/net/ethernet/intel/ixgbe/ixgbe.h         |   14 ++++++++
 drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c |   40 ++++++++++++++++++++++
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c    |    6 +++
 3 files changed, 60 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 04fdbf6..9765772 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -54,6 +54,9 @@
 
 #include <net/ll_poll.h>
 
+#ifdef CONFIG_NET_LL_RX_POLL
+#define LL_EXTENDED_STATS
+#endif
 /* common prefix used by pr_<> macros */
 #undef pr_fmt
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -184,6 +187,11 @@ struct ixgbe_rx_buffer {
 struct ixgbe_queue_stats {
 	u64 packets;
 	u64 bytes;
+#ifdef LL_EXTENDED_STATS
+	u64 yields;
+	u64 misses;
+	u64 cleaned;
+#endif  /* LL_EXTENDED_STATS */
 };
 
 struct ixgbe_tx_queue_stats {
@@ -391,6 +399,9 @@ static inline int ixgbe_qv_lock_napi(struct ixgbe_q_vector *q_vector)
 		WARN_ON(q_vector->state & IXGBE_QV_STATE_NAPI);
 		q_vector->state |= IXGBE_QV_STATE_NAPI_YIELD;
 		rc = false;
+#ifdef LL_EXTENDED_STATS
+		q_vector->tx.ring->stats.yields++;
+#endif
 	} else
 		/* we don't care if someone yielded */
 		q_vector->state = IXGBE_QV_STATE_NAPI;
@@ -421,6 +432,9 @@ static inline int ixgbe_qv_lock_poll(struct ixgbe_q_vector *q_vector)
 	if ((q_vector->state & IXGBE_QV_LOCKED)) {
 		q_vector->state |= IXGBE_QV_STATE_POLL_YIELD;
 		rc = false;
+#ifdef LL_EXTENDED_STATS
+		q_vector->rx.ring->stats.yields++;
+#endif
 	} else
 		/* preserve yield marks */
 		q_vector->state |= IXGBE_QV_STATE_POLL;
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
index d375472..24e2e7a 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
@@ -1054,6 +1054,12 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
 			data[i] = 0;
 			data[i+1] = 0;
 			i += 2;
+#ifdef LL_EXTENDED_STATS
+			data[i] = 0;
+			data[i+1] = 0;
+			data[i+2] = 0;
+			i += 3;
+#endif
 			continue;
 		}
 
@@ -1063,6 +1069,12 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
 			data[i+1] = ring->stats.bytes;
 		} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
 		i += 2;
+#ifdef LL_EXTENDED_STATS
+		data[i] = ring->stats.yields;
+		data[i+1] = ring->stats.misses;
+		data[i+2] = ring->stats.cleaned;
+		i += 3;
+#endif
 	}
 	for (j = 0; j < IXGBE_NUM_RX_QUEUES; j++) {
 		ring = adapter->rx_ring[j];
@@ -1070,6 +1082,12 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
 			data[i] = 0;
 			data[i+1] = 0;
 			i += 2;
+#ifdef LL_EXTENDED_STATS
+			data[i] = 0;
+			data[i+1] = 0;
+			data[i+2] = 0;
+			i += 3;
+#endif
 			continue;
 		}
 
@@ -1079,6 +1097,12 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
 			data[i+1] = ring->stats.bytes;
 		} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
 		i += 2;
+#ifdef LL_EXTENDED_STATS
+		data[i] = ring->stats.yields;
+		data[i+1] = ring->stats.misses;
+		data[i+2] = ring->stats.cleaned;
+		i += 3;
+#endif
 	}
 
 	for (j = 0; j < IXGBE_MAX_PACKET_BUFFERS; j++) {
@@ -1115,12 +1139,28 @@ static void ixgbe_get_strings(struct net_device *netdev, u32 stringset,
 			p += ETH_GSTRING_LEN;
 			sprintf(p, "tx_queue_%u_bytes", i);
 			p += ETH_GSTRING_LEN;
+#ifdef LL_EXTENDED_STATS
+			sprintf(p, "tx_q_%u_napi_yield", i);
+			p += ETH_GSTRING_LEN;
+			sprintf(p, "tx_q_%u_misses", i);
+			p += ETH_GSTRING_LEN;
+			sprintf(p, "tx_q_%u_cleaned", i);
+			p += ETH_GSTRING_LEN;
+#endif /* LL_EXTENDED_STATS */
 		}
 		for (i = 0; i < IXGBE_NUM_RX_QUEUES; i++) {
 			sprintf(p, "rx_queue_%u_packets", i);
 			p += ETH_GSTRING_LEN;
 			sprintf(p, "rx_queue_%u_bytes", i);
 			p += ETH_GSTRING_LEN;
+#ifdef LL_EXTENDED_STATS
+			sprintf(p, "rx_q_%u_ll_poll_yield", i);
+			p += ETH_GSTRING_LEN;
+			sprintf(p, "rx_q_%u_misses", i);
+			p += ETH_GSTRING_LEN;
+			sprintf(p, "rx_q_%u_cleaned", i);
+			p += ETH_GSTRING_LEN;
+#endif /* LL_EXTENDED_STATS */
 		}
 		for (i = 0; i < IXGBE_MAX_PACKET_BUFFERS; i++) {
 			sprintf(p, "tx_pb_%u_pxon", i);
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 9a7dc40..047ebaa 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -2016,6 +2016,12 @@ static int ixgbe_low_latency_recv(struct napi_struct *napi)
 
 	ixgbe_for_each_ring(ring, q_vector->rx) {
 		found = ixgbe_clean_rx_irq(q_vector, ring, 4);
+#ifdef LL_EXTENDED_STATS
+		if (found)
+			ring->stats.cleaned += found;
+		else
+			ring->stats.misses++;
+#endif
 		if (found)
 			break;
 	}


------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
E1000-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired

Re: [PATCH v7 net-next 0/5] net: low latency Ethernet device polling

[Eliezer Tamir]

On 30/05/2013 14:40, Eliezer Tamir wrote:
> more fixes.
> Thank you all for your input.
>
> -Eliezer
>
> change log:
> v7
> - suggested by Ben Hutchings and Eric Dumazet:
>    type fixes, static for globals in net/core.c,
>    avoid napi_id collisions in napi_hash_add()

Dave,

Please tell my how you think I should proceed.
If you think v7 is good enough I can send a cleanup patch for the
type fixes that were suggested.
Or I can submit a v8 with those fixes.

Once we are done with what we have so far, I plan on working on adding
all the things we think are needed for a fuller implementation.
I hope to submit an RFC in a few weeks.

Thanks,
Eliezer

Re: [PATCH v7 net-next 0/5] net: low latency Ethernet device polling

[David Miller]

From: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Date: Sun, 02 Jun 2013 17:02:33 +0300

> Or I can submit a v8 with those fixes.

Please submit v8