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[DST]: shrinks sizeof(struct rtable) by 64 bytes on x86_64 

On x86_64, sizeof(struct rtable) is 0x148, which is rounded up to
0x180 bytes by SLAB allocator.

We can reduce this to exactly 0x140 bytes, without alignment overhead,
and store 12 struct rtable per PAGE instead of 10.

rate_tokens is currently defined as an "unsigned long", while its
content should not exceed 6*HZ. It can safely be converted to an
unsigned int.

Moving tclassid right after rate_tokens to fill the 4 bytes hole
permits to save 8 bytes on 'struct dst_entry', which finally permits
to save 8 bytes on 'struct rtable'

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2008-01-22 06:18:34 -08:00 committed by David S. Miller
parent 81566e8322
commit 69a73829db
2 changed files with 12 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/net/dst.h
View File

@ -56,7 +56,11 @@ struct dst_entry
struct dst_entry *path;
unsigned long rate_last; /* rate limiting for ICMP */
unsigned long rate_tokens;
unsigned int rate_tokens;
#ifdef CONFIG_NET_CLS_ROUTE
__u32 tclassid;
#endif
struct neighbour *neighbour;
struct hh_cache *hh;
@ -65,10 +69,6 @@ struct dst_entry
int (*input)(struct sk_buff*);
int (*output)(struct sk_buff*);
#ifdef CONFIG_NET_CLS_ROUTE
__u32 tclassid;
#endif
struct dst_ops *ops;
unsigned long lastuse;

13
net/ipv4/icmp.c
View File

@ -275,18 +275,19 @@ static inline void icmp_xmit_unlock(void)
#define XRLIM_BURST_FACTOR 6
int xrlim_allow(struct dst_entry *dst, int timeout)
{
unsigned long now;
unsigned long now, token = dst->rate_tokens;
int rc = 0;
now = jiffies;
dst->rate_tokens += now - dst->rate_last;
token += now - dst->rate_last;
dst->rate_last = now;
if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout)
dst->rate_tokens = XRLIM_BURST_FACTOR * timeout;
if (dst->rate_tokens >= timeout) {
dst->rate_tokens -= timeout;
if (token > XRLIM_BURST_FACTOR * timeout)
token = XRLIM_BURST_FACTOR * timeout;
if (token >= timeout) {
token -= timeout;
rc = 1;
}
dst->rate_tokens = token;
return rc;
}