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Message-ID: <20231204201232.520025-2-lixiaoyan@google.com>
Date: Mon, 4 Dec 2023 20:12:30 +0000
From: Coco Li <lixiaoyan@...gle.com>
To: Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>,
Neal Cardwell <ncardwell@...gle.com>, Mubashir Adnan Qureshi <mubashirq@...gle.com>,
Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>, Jonathan Corbet <corbet@....net>,
David Ahern <dsahern@...nel.org>, Daniel Borkmann <daniel@...earbox.net>
Cc: netdev@...r.kernel.org, Chao Wu <wwchao@...gle.com>, Wei Wang <weiwan@...gle.com>,
Pradeep Nemavat <pnemavat@...gle.com>, Coco Li <lixiaoyan@...gle.com>
Subject: [PATCH v1 net-next 1/2] net-device: reorganize net_device fast path variables
Reorganize fast path variables on tx-txrx-rx order
Fastpath variables end after npinfo.
Below data generated with pahole on x86 architecture.
Fast path variables span cache lines before change: 12
Fast path variables span cache lines after change: 4
Suggested-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Coco Li <lixiaoyan@...gle.com>
---
include/linux/netdevice.h | 117 +++++++++++++++++++++-----------------
net/core/dev.c | 56 ++++++++++++++++++
2 files changed, 120 insertions(+), 53 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c2d74bc112ddc..b7bb725e53939 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2092,6 +2092,70 @@ enum netdev_stat_type {
*/
struct net_device {
+ /* Cacheline organization can be found documented in
+ * Documentation/networking/net_cachelines/net_device.rst.
+ * Please update the document when adding new fields.
+ */
+
+ /* TX read-mostly hotpath */
+ __cacheline_group_begin(net_device_read_tx);
+ unsigned long long priv_flags;
+ const struct net_device_ops *netdev_ops;
+ const struct header_ops *header_ops;
+ struct netdev_queue *_tx;
+ unsigned int real_num_tx_queues;
+ unsigned int gso_max_size;
+ unsigned int gso_ipv4_max_size;
+ u16 gso_max_segs;
+ s16 num_tc;
+ /* Note : dev->mtu is often read without holding a lock.
+ * Writers usually hold RTNL.
+ * It is recommended to use READ_ONCE() to annotate the reads,
+ * and to use WRITE_ONCE() to annotate the writes.
+ */
+ unsigned int mtu;
+ unsigned short needed_headroom;
+ struct netdev_tc_txq tc_to_txq[TC_MAX_QUEUE];
+#ifdef CONFIG_XPS
+ struct xps_dev_maps __rcu *xps_maps[XPS_MAPS_MAX];
+#endif
+#ifdef CONFIG_NETFILTER_EGRESS
+ struct nf_hook_entries __rcu *nf_hooks_egress;
+#endif
+#ifdef CONFIG_NET_XGRESS
+ struct bpf_mprog_entry __rcu *tcx_egress;
+#endif
+ __cacheline_group_end(net_device_read_tx);
+
+ /* TXRX read-mostly hotpath */
+ __cacheline_group_begin(net_device_read_txrx);
+ unsigned int flags;
+ unsigned short hard_header_len;
+ netdev_features_t features;
+ struct inet6_dev __rcu *ip6_ptr;
+ __cacheline_group_end(net_device_read_txrx);
+
+ /* RX read-mostly hotpath */
+ __cacheline_group_begin(net_device_read_rx);
+ struct list_head ptype_specific;
+ int ifindex;
+ unsigned int real_num_rx_queues;
+ struct netdev_rx_queue *_rx;
+ unsigned long gro_flush_timeout;
+ int napi_defer_hard_irqs;
+ unsigned int gro_max_size;
+ unsigned int gro_ipv4_max_size;
+ rx_handler_func_t __rcu *rx_handler;
+ void __rcu *rx_handler_data;
+ possible_net_t nd_net;
+#ifdef CONFIG_NETPOLL
+ struct netpoll_info __rcu *npinfo;
+#endif
+#ifdef CONFIG_NET_XGRESS
+ struct bpf_mprog_entry __rcu *tcx_ingress;
+#endif
+ __cacheline_group_end(net_device_read_rx);
+
char name[IFNAMSIZ];
struct netdev_name_node *name_node;
struct dev_ifalias __rcu *ifalias;
@@ -2116,7 +2180,6 @@ struct net_device {
struct list_head unreg_list;
struct list_head close_list;
struct list_head ptype_all;
- struct list_head ptype_specific;
struct {
struct list_head upper;
@@ -2124,26 +2187,13 @@ struct net_device {
} adj_list;
/* Read-mostly cache-line for fast-path access */
- unsigned int flags;
xdp_features_t xdp_features;
- unsigned long long priv_flags;
- const struct net_device_ops *netdev_ops;
const struct xdp_metadata_ops *xdp_metadata_ops;
const struct xsk_tx_metadata_ops *xsk_tx_metadata_ops;
- int ifindex;
unsigned short gflags;
- unsigned short hard_header_len;
- /* Note : dev->mtu is often read without holding a lock.
- * Writers usually hold RTNL.
- * It is recommended to use READ_ONCE() to annotate the reads,
- * and to use WRITE_ONCE() to annotate the writes.
- */
- unsigned int mtu;
- unsigned short needed_headroom;
unsigned short needed_tailroom;
- netdev_features_t features;
netdev_features_t hw_features;
netdev_features_t wanted_features;
netdev_features_t vlan_features;
@@ -2187,8 +2237,6 @@ struct net_device {
const struct tlsdev_ops *tlsdev_ops;
#endif
- const struct header_ops *header_ops;
-
unsigned char operstate;
unsigned char link_mode;
@@ -2229,9 +2277,7 @@ struct net_device {
/* Protocol-specific pointers */
-
struct in_device __rcu *ip_ptr;
- struct inet6_dev __rcu *ip6_ptr;
#if IS_ENABLED(CONFIG_VLAN_8021Q)
struct vlan_info __rcu *vlan_info;
#endif
@@ -2266,26 +2312,14 @@ struct net_device {
/* Interface address info used in eth_type_trans() */
const unsigned char *dev_addr;
- struct netdev_rx_queue *_rx;
unsigned int num_rx_queues;
- unsigned int real_num_rx_queues;
-
struct bpf_prog __rcu *xdp_prog;
- unsigned long gro_flush_timeout;
- int napi_defer_hard_irqs;
#define GRO_LEGACY_MAX_SIZE 65536u
/* TCP minimal MSS is 8 (TCP_MIN_GSO_SIZE),
* and shinfo->gso_segs is a 16bit field.
*/
#define GRO_MAX_SIZE (8 * 65535u)
- unsigned int gro_max_size;
- unsigned int gro_ipv4_max_size;
unsigned int xdp_zc_max_segs;
- rx_handler_func_t __rcu *rx_handler;
- void __rcu *rx_handler_data;
-#ifdef CONFIG_NET_XGRESS
- struct bpf_mprog_entry __rcu *tcx_ingress;
-#endif
struct netdev_queue __rcu *ingress_queue;
#ifdef CONFIG_NETFILTER_INGRESS
struct nf_hook_entries __rcu *nf_hooks_ingress;
@@ -2300,25 +2334,13 @@ struct net_device {
/*
* Cache lines mostly used on transmit path
*/
- struct netdev_queue *_tx ____cacheline_aligned_in_smp;
unsigned int num_tx_queues;
- unsigned int real_num_tx_queues;
struct Qdisc __rcu *qdisc;
unsigned int tx_queue_len;
spinlock_t tx_global_lock;
struct xdp_dev_bulk_queue __percpu *xdp_bulkq;
-#ifdef CONFIG_XPS
- struct xps_dev_maps __rcu *xps_maps[XPS_MAPS_MAX];
-#endif
-#ifdef CONFIG_NET_XGRESS
- struct bpf_mprog_entry __rcu *tcx_egress;
-#endif
-#ifdef CONFIG_NETFILTER_EGRESS
- struct nf_hook_entries __rcu *nf_hooks_egress;
-#endif
-
#ifdef CONFIG_NET_SCHED
DECLARE_HASHTABLE (qdisc_hash, 4);
#endif
@@ -2357,12 +2379,6 @@ struct net_device {
bool needs_free_netdev;
void (*priv_destructor)(struct net_device *dev);
-#ifdef CONFIG_NETPOLL
- struct netpoll_info __rcu *npinfo;
-#endif
-
- possible_net_t nd_net;
-
/* mid-layer private */
void *ml_priv;
enum netdev_ml_priv_type ml_priv_type;
@@ -2397,20 +2413,15 @@ struct net_device {
*/
#define GSO_MAX_SIZE (8 * GSO_MAX_SEGS)
- unsigned int gso_max_size;
#define TSO_LEGACY_MAX_SIZE 65536
#define TSO_MAX_SIZE UINT_MAX
unsigned int tso_max_size;
- u16 gso_max_segs;
#define TSO_MAX_SEGS U16_MAX
u16 tso_max_segs;
- unsigned int gso_ipv4_max_size;
#ifdef CONFIG_DCB
const struct dcbnl_rtnl_ops *dcbnl_ops;
#endif
- s16 num_tc;
- struct netdev_tc_txq tc_to_txq[TC_MAX_QUEUE];
u8 prio_tc_map[TC_BITMASK + 1];
#if IS_ENABLED(CONFIG_FCOE)
diff --git a/net/core/dev.c b/net/core/dev.c
index 3950ced396b50..4779689f7c437 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -11572,6 +11572,60 @@ static struct pernet_operations __net_initdata default_device_ops = {
.exit_batch = default_device_exit_batch,
};
+static void __init net_dev_struct_check(void)
+{
+ /* TX read-mostly hotpath */
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, priv_flags);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, netdev_ops);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, header_ops);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, _tx);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, real_num_tx_queues);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, gso_max_size);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, gso_ipv4_max_size);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, gso_max_segs);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, num_tc);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, mtu);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, needed_headroom);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, tc_to_txq);
+#ifdef CONFIG_XPS
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, xps_maps);
+#endif
+#ifdef CONFIG_NETFILTER_EGRESS
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, nf_hooks_egress);
+#endif
+#ifdef CONFIG_NET_XGRESS
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, tcx_egress);
+#endif
+ CACHELINE_ASSERT_GROUP_SIZE(struct net_device, net_device_read_tx, 152);
+
+ /* TXRX read-mostly hotpath */
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, flags);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, hard_header_len);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, features);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, ip6_ptr);
+ CACHELINE_ASSERT_GROUP_SIZE(struct net_device, net_device_read_txrx, 30);
+
+ /* RX read-mostly hotpath */
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, ptype_specific);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, ifindex);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, real_num_rx_queues);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, _rx);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, gro_flush_timeout);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, napi_defer_hard_irqs);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, gro_max_size);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, gro_ipv4_max_size);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, rx_handler);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, rx_handler_data);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, nd_net);
+#ifdef CONFIG_NETPOLL
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, npinfo);
+#endif
+#ifdef CONFIG_NET_XGRESS
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, tcx_ingress);
+#endif
+ CACHELINE_ASSERT_GROUP_SIZE(struct net_device, net_device_read_rx, 96);
+}
+
/*
* Initialize the DEV module. At boot time this walks the device list and
* unhooks any devices that fail to initialise (normally hardware not
@@ -11589,6 +11643,8 @@ static int __init net_dev_init(void)
BUG_ON(!dev_boot_phase);
+ net_dev_struct_check();
+
if (dev_proc_init())
goto out;
--
2.43.0.rc2.451.g8631bc7472-goog
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