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[NET]: Implement SKB fast cloning.

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Protocols that make extensive use of SKB cloning,
for example TCP, eat at least 2 allocations per
packet sent as a result.

To cut the kmalloc() count in half, we implement
a pre-allocation scheme wherein we allocate
2 sk_buff objects in advance, then use a simple
reference count to free up the memory at the
correct time.

Based upon an initial patch by Thomas Graf and
suggestions from Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2005-08-17 14:57:30 -07:00
committed by David S. Miller
parent e92ae93a8a
commit d179cd1292
4 changed files with 97 additions and 15 deletions
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26
include/linux/skbuff.h
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@ -162,6 +162,13 @@ struct skb_timeval {
u32 off_usec;
};
enum {
SKB_FCLONE_UNAVAILABLE,
SKB_FCLONE_ORIG,
SKB_FCLONE_CLONE,
};
/**
* struct sk_buff - socket buffer
* @next: Next buffer in list
@ -255,7 +262,8 @@ struct sk_buff {
ip_summed:2,
nohdr:1,
nfctinfo:3;
__u8 pkt_type;
__u8 pkt_type:3,
fclone:2;
__be16 protocol;
void (*destructor)(struct sk_buff *skb);
@ -295,8 +303,20 @@ struct sk_buff {
#include <asm/system.h>
extern void __kfree_skb(struct sk_buff *skb);
extern struct sk_buff *alloc_skb(unsigned int size,
unsigned int __nocast priority);
extern struct sk_buff *__alloc_skb(unsigned int size,
unsigned int __nocast priority, int fclone);
static inline struct sk_buff *alloc_skb(unsigned int size,
unsigned int __nocast priority)
{
return __alloc_skb(size, priority, 0);
}
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
unsigned int __nocast priority)
{
return __alloc_skb(size, priority, 1);
}
extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
unsigned int size,
unsigned int __nocast priority);