OpenWrt – Rev 4
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From 9115e8cd2a0c6eaaa900c462721f12e1d45f326c Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Sat, 3 Dec 2016 11:14:56 -0800
Subject: [PATCH 07/10] net: reorganize struct sock for better data locality
Group fields used in TX path, and keep some cache lines mostly read
to permit sharing among cpus.
Gained two 4 bytes holes on 64bit arches.
Added a place holder for tcp tsq_flags, next to sk_wmem_alloc
to speed up tcp_wfree() in the following patch.
I have not added ____cacheline_aligned_in_smp, this might be done later.
I prefer doing this once inet and tcp/udp sockets reorg is also done.
Tested with both TCP and UDP.
UDP receiver performance under flood increased by ~20 % :
Accessing sk_filter/sk_wq/sk_napi_id no longer stalls because sk_drops
was moved away from a critical cache line, now mostly read and shared.
/* --- cacheline 4 boundary (256 bytes) --- */
unsigned int sk_napi_id; /* 0x100 0x4 */
int sk_rcvbuf; /* 0x104 0x4 */
struct sk_filter * sk_filter; /* 0x108 0x8 */
union {
struct socket_wq * sk_wq; /* 0x8 */
struct socket_wq * sk_wq_raw; /* 0x8 */
}; /* 0x110 0x8 */
struct xfrm_policy * sk_policy[2]; /* 0x118 0x10 */
struct dst_entry * sk_rx_dst; /* 0x128 0x8 */
struct dst_entry * sk_dst_cache; /* 0x130 0x8 */
atomic_t sk_omem_alloc; /* 0x138 0x4 */
int sk_sndbuf; /* 0x13c 0x4 */
/* --- cacheline 5 boundary (320 bytes) --- */
int sk_wmem_queued; /* 0x140 0x4 */
atomic_t sk_wmem_alloc; /* 0x144 0x4 */
long unsigned int sk_tsq_flags; /* 0x148 0x8 */
struct sk_buff * sk_send_head; /* 0x150 0x8 */
struct sk_buff_head sk_write_queue; /* 0x158 0x18 */
__s32 sk_peek_off; /* 0x170 0x4 */
int sk_write_pending; /* 0x174 0x4 */
long int sk_sndtimeo; /* 0x178 0x8 */
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/sock.h | 51 +++++++++++++++++++++++++++------------------------
1 file changed, 27 insertions(+), 24 deletions(-)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -344,6 +344,9 @@ struct sock {
#define sk_rxhash __sk_common.skc_rxhash
socket_lock_t sk_lock;
+ atomic_t sk_drops;
+ int sk_rcvlowat;
+ struct sk_buff_head sk_error_queue;
struct sk_buff_head sk_receive_queue;
/*
* The backlog queue is special, it is always used with
@@ -360,14 +363,13 @@ struct sock {
struct sk_buff *tail;
} sk_backlog;
#define sk_rmem_alloc sk_backlog.rmem_alloc
- int sk_forward_alloc;
- __u32 sk_txhash;
+ int sk_forward_alloc;
#ifdef CONFIG_NET_RX_BUSY_POLL
- unsigned int sk_napi_id;
unsigned int sk_ll_usec;
+ /* ===== mostly read cache line ===== */
+ unsigned int sk_napi_id;
#endif
- atomic_t sk_drops;
int sk_rcvbuf;
struct sk_filter __rcu *sk_filter;
@@ -380,11 +382,30 @@ struct sock {
#endif
struct dst_entry *sk_rx_dst;
struct dst_entry __rcu *sk_dst_cache;
- /* Note: 32bit hole on 64bit arches */
- atomic_t sk_wmem_alloc;
atomic_t sk_omem_alloc;
int sk_sndbuf;
+
+ /* ===== cache line for TX ===== */
+ int sk_wmem_queued;
+ atomic_t sk_wmem_alloc;
+ unsigned long sk_tsq_flags;
+ struct sk_buff *sk_send_head;
struct sk_buff_head sk_write_queue;
+ __s32 sk_peek_off;
+ int sk_write_pending;
+ long sk_sndtimeo;
+ struct timer_list sk_timer;
+ __u32 sk_priority;
+ __u32 sk_mark;
+ u32 sk_pacing_rate; /* bytes per second */
+ u32 sk_max_pacing_rate;
+ struct page_frag sk_frag;
+ netdev_features_t sk_route_caps;
+ netdev_features_t sk_route_nocaps;
+ int sk_gso_type;
+ unsigned int sk_gso_max_size;
+ gfp_t sk_allocation;
+ __u32 sk_txhash;
/*
* Because of non atomicity rules, all
@@ -400,31 +421,17 @@ struct sock {
#define SK_PROTOCOL_MAX U8_MAX
kmemcheck_bitfield_end(flags);
- int sk_wmem_queued;
- gfp_t sk_allocation;
- u32 sk_pacing_rate; /* bytes per second */
- u32 sk_max_pacing_rate;
- netdev_features_t sk_route_caps;
- netdev_features_t sk_route_nocaps;
- int sk_gso_type;
- unsigned int sk_gso_max_size;
u16 sk_gso_max_segs;
- int sk_rcvlowat;
unsigned long sk_lingertime;
- struct sk_buff_head sk_error_queue;
struct proto *sk_prot_creator;
rwlock_t sk_callback_lock;
int sk_err,
sk_err_soft;
u32 sk_ack_backlog;
u32 sk_max_ack_backlog;
- __u32 sk_priority;
- __u32 sk_mark;
struct pid *sk_peer_pid;
const struct cred *sk_peer_cred;
long sk_rcvtimeo;
- long sk_sndtimeo;
- struct timer_list sk_timer;
ktime_t sk_stamp;
#if BITS_PER_LONG==32
seqlock_t sk_stamp_seq;
@@ -434,10 +441,6 @@ struct sock {
u32 sk_tskey;
struct socket *sk_socket;
void *sk_user_data;
- struct page_frag sk_frag;
- struct sk_buff *sk_send_head;
- __s32 sk_peek_off;
- int sk_write_pending;
#ifdef CONFIG_SECURITY
void *sk_security;
#endif