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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>
This commit is contained in:
Eric Dumazet 2016-12-03 11:14:56 -08:00 committed by David S. Miller
parent 12a59abc22
commit 9115e8cd2a
1 changed files with 27 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
include/net/sock.h
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@ -343,6 +343,9 @@ 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
@ -359,14 +362,13 @@ 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;
@ -379,11 +381,30 @@ 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
@ -414,42 +435,24 @@ 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;
kuid_t sk_uid;
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;
u16 sk_tsflags;
u8 sk_shutdown;
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