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Date: Fri, 4 May 2007 08:24:34 -0300
From: "Arnaldo Carvalho de Melo" <acme@...stprotocols.net>
To: "Eric Dumazet" <dada1@...mosbay.com>
Cc: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH][SOCK]: shrink struct sock
On 5/4/07, Eric Dumazet <dada1@...mosbay.com> wrote:
> Arnaldo Carvalho de Melo a écrit :
> >
> > [acme@...a linux-2.6]$ pahole -C sk_buff_head net/core/sock.o
> > struct sk_buff_head {
> > struct sk_buff * next; /* 0 8 */
> > struct sk_buff * prev; /* 8 8 */
> > __u32 qlen; /* 16 4 */
> > spinlock_t lock; /* 20 8 */
> > }; /* size: 32, cachelines: 1 */
> > /* padding: 4 */
> > /* last cacheline: 32 bytes */
>
>
> Hum, maybe not enough tea this morning, but I always thought spinlock_t size
> was 4 bytes....
Well, unfolding sk_buff_head to see the details:
[acme@...a linux-2.6]$ pahole --expand_types -C sk_buff_head net/core/sock.o
/* <9a61> /home/acme/git/linux-2.6/include/linux/skbuff.h:111 */
struct sk_buff_head {
struct sk_buff * next; /* 0 8 */
struct sk_buff * prev; /* 8 8 */
/* typedef __u32 */ unsigned int qlen; /* 16 4 */
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 20 4 */
} raw_lock; /* 20 4 */
unsigned int break_lock; /* 24 4 */
} lock; /* 20 8 */
}; /* size: 32, cachelines: 1 */
/* padding: 4 */
/* last cacheline: 32 bytes */
#if defined(CONFIG_PREEMPT) && defined(CONFIG_SMP)
unsigned int break_lock;
#endif
Disabling CONFIG_PREEMPT makes you regain your confidence in the
quality of your tea:
[acme@...a linux-2.6]$ pahole --expand_types -C sk_buff_head net/core/sock.o
/* <9a40> /home/acme/git/linux-2.6/include/linux/skbuff.h:111 */
struct sk_buff_head {
struct sk_buff * next; /* 0 8 */
struct sk_buff * prev; /* 8 8 */
/* typedef __u32 */ unsigned int qlen; /* 16 4 */
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 20 4 */
} raw_lock; /* 20 4 */
} lock; /* 20 4 */
}; /* size: 24, cachelines: 1 */
/* last cacheline: 24 bytes */
And then struct sock gets leaner too:
[acme@...a linux-2.6]$ pahole --expand_types -C sock net/core/sock.o
/* <7a57> /home/acme/git/linux-2.6/include/linux/net.h:114 */
struct sock {
struct sock_common {
short unsigned int skc_family; /* 0 2 */
volatile unsigned char skc_state; /* 2 1 */
unsigned char skc_reuse; /* 3 1 */
int skc_bound_dev_if; /* 4 4 */
struct hlist_node {
struct hlist_node * next; /* 8 8 */
struct hlist_node * * pprev; /* 16 8 */
} skc_node; /* 8 16 */
struct hlist_node {
struct hlist_node * next; /* 24 8 */
struct hlist_node * * pprev; /* 32 8 */
} skc_bind_node; /* 24 16 */
/* typedef atomic_t */ struct {
int counter; /* 40 4 */
} skc_refcnt; /* 40 4 */
unsigned int skc_hash; /* 44 4 */
struct proto * skc_prot; /* 48 8 */
} __sk_common; /* 0 56 */
unsigned char sk_shutdown:2; /* 56 1 */
unsigned char sk_no_check:2; /* 56 1 */
unsigned char sk_userlocks:4; /* 56 1 */
unsigned char sk_protocol; /* 57 1 */
short unsigned int sk_type; /* 58 2 */
int sk_rcvbuf; /* 60 4 */
/* --- cacheline 1 boundary (64 bytes) --- */
/* typedef socket_lock_t */ struct {
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 64 4 */
} raw_lock; /* 64 4 */
} slock; /* 64 4 */
struct sock_iocb * owner; /* 72 8 */
/* typedef wait_queue_head_t */ struct __wait_queue_head {
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 80 4 */
} raw_lock; /* 80 4 */
} lock; /* 80 4 */
/* XXX 4 bytes hole, try to pack */
struct list_head {
struct list_head * next; /* 88 8 */
struct list_head * prev; /* 96 8 */
} task_list; /* 88 16 */
} wq; /* 80 24 */
} sk_lock; /* 64 40 */
struct {
struct sk_buff * head; /* 104 8 */
struct sk_buff * tail; /* 112 8 */
} sk_backlog; /* 104 16 */
wait_queue_head_t * sk_sleep; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
struct dst_entry * sk_dst_cache; /* 128 8 */
struct xfrm_policy * sk_policy[2]; /* 136 16 */
/* typedef rwlock_t */ struct {
/* typedef raw_rwlock_t */ struct {
unsigned int lock; /* 152 4 */
} raw_lock; /* 152 4 */
} sk_dst_lock; /* 152 4 */
/* typedef atomic_t */ struct {
int counter; /* 156 4 */
} sk_rmem_alloc; /* 156 4 */
/* typedef atomic_t */ struct {
int counter; /* 160 4 */
} sk_wmem_alloc; /* 160 4 */
/* typedef atomic_t */ struct {
int counter; /* 164 4 */
} sk_omem_alloc; /* 164 4 */
int sk_sndbuf; /* 168 4 */
/* XXX 4 bytes hole, try to pack */
struct sk_buff_head {
struct sk_buff * next; /* 176 8 */
struct sk_buff * prev; /* 184 8 */
/* typedef __u32 */ unsigned int qlen; /* 192 4 */
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 196 4 */
} raw_lock; /* 196 4 */
} lock; /* 196 4 */
} sk_receive_queue; /* 176 24 */
/* --- cacheline 3 boundary (192 bytes) was 8 bytes ago --- */
struct sk_buff_head {
struct sk_buff * next; /* 200 8 */
struct sk_buff * prev; /* 208 8 */
/* typedef __u32 */ unsigned int qlen; /* 216 4 */
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 220 4 */
} raw_lock; /* 220 4 */
} lock; /* 220 4 */
} sk_write_queue; /* 200 24 */
struct sk_buff_head {
struct sk_buff * next; /* 224 8 */
struct sk_buff * prev; /* 232 8 */
/* typedef __u32 */ unsigned int qlen; /* 240 4 */
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 244 4 */
} raw_lock; /* 244 4 */
} lock; /* 244 4 */
} sk_async_wait_queue; /* 224 24 */
int sk_wmem_queued; /* 248 4 */
int sk_forward_alloc; /* 252 4 */
/* --- cacheline 4 boundary (256 bytes) --- */
/* typedef gfp_t */ unsigned int sk_allocation; /* 256 4 */
int sk_route_caps; /* 260 4 */
int sk_gso_type; /* 264 4 */
int sk_rcvlowat; /* 268 4 */
long unsigned int sk_flags; /* 272 8 */
long unsigned int sk_lingertime; /* 280 8 */
struct sk_buff_head {
struct sk_buff * next; /* 288 8 */
struct sk_buff * prev; /* 296 8 */
/* typedef __u32 */ unsigned int qlen; /* 304 4 */
/* typedef spinlock_t */ struct {
/* typedef raw_spinlock_t */ struct {
unsigned int slock; /* 308 4 */
} raw_lock; /* 308 4 */
} lock; /* 308 4 */
} sk_error_queue; /* 288 24 */
struct proto * sk_prot_creator; /* 312 8 */
/* --- cacheline 5 boundary (320 bytes) --- */
/* typedef rwlock_t */ struct {
/* typedef raw_rwlock_t */ struct {
unsigned int lock; /* 320 4 */
} raw_lock; /* 320 4 */
} sk_callback_lock; /* 320 4 */
int sk_err; /* 324 4 */
int sk_err_soft; /* 328 4 */
short unsigned int sk_ack_backlog; /* 332 2 */
short unsigned int sk_max_ack_backlog; /* 334 2 */
/* typedef __u32 */ unsigned int sk_priority; /* 336 4 */
struct ucred {
/* typedef __u32 */ unsigned int pid; /* 340 4 */
/* typedef __u32 */ unsigned int uid; /* 344 4 */
/* typedef __u32 */ unsigned int gid; /* 348 4 */
} sk_peercred; /* 340 12 */
long int sk_rcvtimeo; /* 352 8 */
long int sk_sndtimeo; /* 360 8 */
struct sk_filter * sk_filter; /* 368 8 */
void * sk_protinfo; /* 376 8 */
/* --- cacheline 6 boundary (384 bytes) --- */
struct timer_list {
struct list_head {
struct list_head * next; /* 384 8 */
struct list_head * prev; /* 392 8 */
} entry; /* 384 16 */
long unsigned int expires; /* 400 8 */
void (*function)(long unsigned int); /* 408 8 */
long unsigned int data; /* 416 8 */
struct tvec_t_base_s * base; /* 424 8 */
} sk_timer; /* 384 48 */
/* typedef ktime_t */ union {
/* typedef s64 */ long long int tv64; /* 8 */
} sk_stamp; /* 432 8 */
struct socket * sk_socket; /* 440 8 */
/* --- cacheline 7 boundary (448 bytes) --- */
void * sk_user_data; /* 448 8 */
struct page * sk_sndmsg_page; /* 456 8 */
struct sk_buff * sk_send_head; /* 464 8 */
/* typedef __u32 */ unsigned int sk_sndmsg_off; /* 472 4 */
int sk_write_pending; /* 476 4 */
void * sk_security; /* 480 8 */
void (*sk_state_change)(struct sock *); /* 488 8 */
void (*sk_data_ready)(struct sock *, int); /* 496 8 */
void (*sk_write_space)(struct sock *); /* 504 8 */
/* --- cacheline 8 boundary (512 bytes) --- */
void (*sk_error_report)(struct sock *); /* 512 8 */
int (*sk_backlog_rcv)(struct sock *,
struct sk_buff *); /* 520 8 */
void (*sk_destruct)(struct sock *); /* 528 8 */
}; /* size: 536, cachelines: 9 */
/* sum members: 532, holes: 1, sum holes: 4 */
/* last cacheline: 24 bytes */
- Arnaldo
-
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