David,
Here is v8 with yet more fixes.
Please consider applying.
Thanks to everyone for their input.
-Eliezer
change log:
v8
- split out udp and select/poll into seperate patches.
what used to be patch 2/5 is now three patches.
- type corrections from Amir Vadai and Cong Wang:
one unsigned long that was left when chenging to cycles_t
int -> bool
- more detailed patch descriptions.
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
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 <[email protected]>
---
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)
{
Adds an ndo_ll_poll method and the code that supports it.
This method can be used by low latency applications to busy-poll
Ethernet device queues directly from the socket code.
sysctl_net_ll_poll controls how many microseconds to poll.
Default is zero (disabled).
Individual protocol support will be added by subsequent patches.
Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jesse Brandeburg <[email protected]>
Tested-by: Willem de Bruijn <[email protected]>
Signed-off-by: Eliezer Tamir <[email protected]>
---
Documentation/sysctl/net.txt | 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/skbuff.c | 4 +
net/core/sock.c | 6 ++
net/core/sysctl_net_core.c | 10 +++
net/ipv4/proc.c | 1
net/socket.c | 6 ++
12 files changed, 208 insertions(+), 2 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/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 b999790..908246b 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..abf2fc7
--- /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 <[email protected]>
+ */
+
+/*
+ * 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(cycles_t 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/skbuff.c b/net/core/skbuff.c
index 6b1b52c..73ef74d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -733,6 +733,10 @@ 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/socket.c b/net/socket.c
index 6b94633..721f4e7 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,
Add upport for busy-polling on UDP sockets.
In __udp[46]_lib_rcv add a call to sk_mark_ll() to copy the napi_id
from the skb into the sk.
This is done at the earliest possible moment, right after we identify
which socket this skb is for.
In __skb_recv_datagram When there is no data and the user
tries to read we busy poll.
Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jesse Brandeburg <[email protected]>
Tested-by: Willem de Bruijn <[email protected]>
Signed-off-by: Eliezer Tamir <[email protected]>
---
net/core/datagram.c | 4 ++++
net/ipv4/udp.c | 6 +++++-
net/ipv6/udp.c | 6 +++++-
3 files changed, 14 insertions(+), 2 deletions(-)
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/ipv4/udp.c b/net/ipv4/udp.c
index c7338ec..2955b25 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
Adds low latency socket poll support for TCP.
In tcp_v[46]_rcv() add a call to sk_mark_ll() to copy the napi_id
from the skb to the sk.
In tcp_recvmsg(), when there is no data in the socket we busy-poll.
This is a good example of how to add busy-poll support to more protocols.
Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jesse Brandeburg <[email protected]>
Tested-by: Willem de Bruijn <[email protected]>
Signed-off-by: Eliezer Tamir <[email protected]>
---
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 b5d4ad9..bf09f6b 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;
@@ -1553,6 +1554,10 @@ 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);
A very naive select/poll busy-poll support.
Add busy-polling to sock_poll().
When poll/select have nothing to report, call the low-level
sock_poll() again untill we are out of time or we find something.
Rigth now we poll every socket once, this is subpotimal
but impoves latency when the number of sockets polled is not large.
Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jesse Brandeburg <[email protected]>
Tested-by: Willem de Bruijn <[email protected]>
Signed-off-by: Eliezer Tamir <[email protected]>
---
fs/select.c | 7 +++++++
net/socket.c | 10 +++++++++-
2 files changed, 16 insertions(+), 1 deletions(-)
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/net/socket.c b/net/socket.c
index 721f4e7..02d0e15 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1148,13 +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)
Add additional statistics to the ixgbe driver for ndo_ll_poll
Defined under LL_EXTENDED_STATS
Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jesse Brandeburg <[email protected]>
Tested-by: Willem de Bruijn <[email protected]>
Signed-off-by: Eliezer Tamir <[email protected]>
---
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 046196c..afacabb 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 bool 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 bool 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;
}
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.
Add each napi to the napi_hash right after netif_napi_add().
Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jesse Brandeburg <[email protected]>
Tested-by: Willem de Bruijn <[email protected]>
Signed-off-by: Eliezer Tamir <[email protected]>
---
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..046196c 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 bool 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 bool 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 bool 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 bool 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 bool 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 bool ixgbe_qv_lock_napi(struct ixgbe_q_vector *q_vector)
+{
+ return true;
+}
+
+static inline bool ixgbe_qv_unlock_napi(struct ixgbe_q_vector *q_vector)
+{
+ return false;
+}
+
+static inline bool ixgbe_qv_lock_poll(struct ixgbe_q_vector *q_vector)
+{
+ return false;
+}
+
+static inline bool ixgbe_qv_unlock_poll(struct ixgbe_q_vector *q_vector)
+{
+ return false;
+}
+
+static inline bool 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,
Acked-By: Amir Vadai <[email protected]>
Nice work Eliezer :)
On 03/06/2013 11:01, Eliezer Tamir wrote:
> David,
>
> Here is v8 with yet more fixes.
>
> Please consider applying.
>
> Thanks to everyone for their input.
>
> -Eliezer
>
> change log:
> v8
> - split out udp and select/poll into seperate patches.
> what used to be patch 2/5 is now three patches.
> - type corrections from Amir Vadai and Cong Wang:
> one unsigned long that was left when chenging to cycles_t
> int -> bool
> - more detailed patch descriptions.
>
> 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
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
On 03/06/2013 11:01, Eliezer Tamir wrote:
> 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),
One more thing I just noticed: should be 'sizeof(int)'.
Because proc_dointvec is expecting an int, sizeof(unsigned long) will
produce an array of two ints.
> + .mode = 0644,
> + .proc_handler = proc_dointvec
> + },
> +#endif
> #endif /* CONFIG_NET */
> {
> .procname = "netdev_budget",
On Mon, 2013-06-03 at 11:01 +0300, Eliezer Tamir wrote:
> 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 <[email protected]>
> ---
>
> include/linux/netdevice.h | 29 ++++++++++++++++++++++
> net/core/dev.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 88 insertions(+), 0 deletions(-)
Signed-off-by: Eric Dumazet <[email protected]>
On Mon, 2013-06-03 at 11:01 +0300, Eliezer Tamir wrote:
> Adds an ndo_ll_poll method and the code that supports it.
> This method can be used by low latency applications to busy-poll
> Ethernet device queues directly from the socket code.
> sysctl_net_ll_poll controls how many microseconds to poll.
> Default is zero (disabled).
> Individual protocol support will be added by subsequent patches.
>
> Signed-off-by: Alexander Duyck <[email protected]>
> Signed-off-by: Jesse Brandeburg <[email protected]>
> Tested-by: Willem de Bruijn <[email protected]>
> Signed-off-by: Eliezer Tamir <[email protected]>
> ---
...
> diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
> +
> +static inline bool sk_valid_ll(struct sock *sk)
> +{
> + return 0;
return false;
> +}
> +
> +static inline bool sk_poll_ll(struct sock *sk, int nonblock)
> +{
> + return 0;
return false;
> +}
> +
> +static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi)
> +{
> +}
> /*
> * 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
proc_doulongvec_minmax
On Mon, 2013-06-03 at 11:01 +0300, Eliezer Tamir wrote:
> Add upport for busy-polling on UDP sockets.
> In __udp[46]_lib_rcv add a call to sk_mark_ll() to copy the napi_id
> from the skb into the sk.
> This is done at the earliest possible moment, right after we identify
> which socket this skb is for.
> In __skb_recv_datagram When there is no data and the user
> tries to read we busy poll.
>
> Signed-off-by: Alexander Duyck <[email protected]>
> Signed-off-by: Jesse Brandeburg <[email protected]>
> Tested-by: Willem de Bruijn <[email protected]>
> Signed-off-by: Eliezer Tamir <[email protected]>
> ---
Reviewed-by: Eric Dumazet <[email protected]>
On Mon, 2013-06-03 at 11:01 +0300, Eliezer Tamir wrote:
> Adds low latency socket poll support for TCP.
> In tcp_v[46]_rcv() add a call to sk_mark_ll() to copy the napi_id
> from the skb to the sk.
> In tcp_recvmsg(), when there is no data in the socket we busy-poll.
> This is a good example of how to add busy-poll support to more protocols.
>
> Signed-off-by: Alexander Duyck <[email protected]>
> Signed-off-by: Jesse Brandeburg <[email protected]>
> Tested-by: Willem de Bruijn <[email protected]>
> Signed-off-by: Eliezer Tamir <[email protected]>
> ---
Reviewed-by: Eric Dumazet <[email protected]>
On Mon, 2013-06-03 at 11:02 +0300, Eliezer Tamir wrote:
> A very naive select/poll busy-poll support.
> Add busy-polling to sock_poll().
> When poll/select have nothing to report, call the low-level
> sock_poll() again untill we are out of time or we find something.
> Rigth now we poll every socket once, this is subpotimal
> but impoves latency when the number of sockets polled is not large.
>
> Signed-off-by: Alexander Duyck <[email protected]>
> Signed-off-by: Jesse Brandeburg <[email protected]>
> Tested-by: Willem de Bruijn <[email protected]>
> Signed-off-by: Eliezer Tamir <[email protected]>
> ---
>
> fs/select.c | 7 +++++++
> net/socket.c | 10 +++++++++-
> 2 files changed, 16 insertions(+), 1 deletions(-)
>
> 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/net/socket.c b/net/socket.c
> index 721f4e7..02d0e15 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -1148,13 +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)
>
In fact, for TCP, POLLOUT event being ready can also be triggered by
incoming messages, as the ACK might allow the user application to push
more data in the write queue.
And you might check wait->_key to avoid testing flags that user is not
interested into.
On 03/06/2013 16:05, Eric Dumazet wrote:
> On Mon, 2013-06-03 at 11:01 +0300, Eliezer Tamir wrote:
>> --- 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
>
> proc_doulongvec_minmax
Thank you.
On 03/06/2013 16:15, Eric Dumazet wrote:
> On Mon, 2013-06-03 at 11:02 +0300, Eliezer Tamir wrote:
>> 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)
>>
>
>
> In fact, for TCP, POLLOUT event being ready can also be triggered by
> incoming messages, as the ACK might allow the user application to push
> more data in the write queue.
>
> And you might check wait->_key to avoid testing flags that user is not
> interested into.
yes, comparing to _key is more correct.
In any case this needs to be completely rewritten for support for
working well with a large number of sockets.
-Eliezer
On 03/06/2013 16:59, Eliezer Tamir wrote:
> On 03/06/2013 16:15, Eric Dumazet wrote:
>> On Mon, 2013-06-03 at 11:02 +0300, Eliezer Tamir wrote:
>>> 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)
>>>
>>
>>
>> In fact, for TCP, POLLOUT event being ready can also be triggered by
>> incoming messages, as the ACK might allow the user application to push
>> more data in the write queue.
>>
>> And you might check wait->_key to avoid testing flags that user is not
>> interested into.
>
> yes, comparing to _key is more correct.
> In any case this needs to be completely rewritten for support for
> working well with a large number of sockets.
>
Is it possible for wait to be NULL? (do we need to check for that?)
I see that poll_does_not_wait() checks for that, but I could not find
anywhere this is actually done.
-Eliezer