Through a combination of several things, our route structures are
larger than they need to be.
Mostly this stems from having members in dst_entry which are only used
by one class of routes. So the majority of the work in this series is
about "un-commoning" these members and pushing them into the type
specific structures.
Unfortunately, IPSEC needed the most surgery. The majority of the
changes here had to do with bundle creation and management.
The other issue is the refcount alignment in dst_entry. Once we get
rid of the not-so-common members, it really opens the door to removing
that alignment entirely.
I think the new layout looks really nice, so I'll reproduce it here:
struct net_device *dev;
struct dst_ops *ops;
unsigned long _metrics;
unsigned long expires;
struct xfrm_state *xfrm;
int (*input)(struct sk_buff *);
int (*output)(struct net *net, struct sock *sk,
struct sk_buff *skb);
unsigned short flags;
short obsolete;
unsigned short header_len;
unsigned short trailer_len;
atomic_t __refcnt;
int __use;
unsigned long lastuse;
struct lwtunnel_state *lwtstate;
struct rcu_head rcu_head;
short error;
short __pad;
__u32 tclassid;
(This is for 64-bit, on 32-bit the __refcnt comes at the very end)
So, the good news:
1) struct dst_entry shrinks from 160 to 112 bytes.
2) struct rtable shrinks from 216 to 168 bytes.
3) struct rt6_info shrinks from 384 to 320 bytes.
Enjoy.
v2:
Collapse some patches logically based upon feedback.
Fix the strange patch #7.
v3: xfrm_dst_path() needs inline keyword
Properly align __refcnt on 32-bit.
Signed-off-by: David S. Miller <da...@davemloft.net>
