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[IPV4] FIB_HASH: Reduce memory needs and speedup lookups 

Currently, sizeof(struct fib_alias) is 24 or 48 bytes on 32/64 bits
arches.

Because of SLAB_HWCACHE_ALIGN requirement, these are rounded to 32 and
64 bytes respectively.

This patch moves rcu to the end of fib_alias, and conditionally
defines it only for CONFIG_IP_FIB_TRIE.

We also remove SLAB_HWCACHE_ALIGN requirement for fib_alias and
fib_node objects because it is not necessary.

(BTW SLUB currently denies it for objects smaller than
cache_line_size() / 2, but not SLAB)

Finally, sizeof(fib_alias) go back to 16 and 32 bytes.

Then, we can embed one fib_alias on each fib_node, to favor locality.
Most of the time access to the fib_alias will be free because one
cache line contains both the list head (fn_alias) and (one of) the
list element.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2008-01-18 03:33:26 -08:00 committed by David S. Miller
parent b59cfbf77d
commit a6501e080c
2 changed files with 23 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
net/ipv4/fib_hash.c
View File

@ -52,6 +52,7 @@ struct fib_node {
struct hlist_node fn_hash;
struct list_head fn_alias;
__be32 fn_key;
struct fib_alias fn_embedded_alias;
};
struct fn_zone {
@ -193,10 +194,13 @@ static inline void fn_free_node(struct fib_node * f)
kmem_cache_free(fn_hash_kmem, f);
}
static inline void fn_free_alias(struct fib_alias *fa)
static inline void fn_free_alias(struct fib_alias *fa, struct fib_node *f)
{
fib_release_info(fa->fa_info);
kmem_cache_free(fn_alias_kmem, fa);
if (fa == &f->fn_embedded_alias)
fa->fa_info = NULL;
else
kmem_cache_free(fn_alias_kmem, fa);
}
static struct fn_zone *
@ -476,15 +480,12 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
goto out;
err = -ENOBUFS;
new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
if (new_fa == NULL)
goto out;
new_f = NULL;
if (!f) {
new_f = kmem_cache_alloc(fn_hash_kmem, GFP_KERNEL);
new_f = kmem_cache_zalloc(fn_hash_kmem, GFP_KERNEL);
if (new_f == NULL)
goto out_free_new_fa;
goto out;
INIT_HLIST_NODE(&new_f->fn_hash);
INIT_LIST_HEAD(&new_f->fn_alias);
@ -492,6 +493,12 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
f = new_f;
}
new_fa = &f->fn_embedded_alias;
if (new_fa->fa_info != NULL) {
new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
if (new_fa == NULL)
goto out_free_new_f;
}
new_fa->fa_info = fi;
new_fa->fa_tos = tos;
new_fa->fa_type = cfg->fc_type;
@ -518,8 +525,8 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
&cfg->fc_nlinfo, 0);
return 0;
out_free_new_fa:
kmem_cache_free(fn_alias_kmem, new_fa);
out_free_new_f:
kmem_cache_free(fn_hash_kmem, new_f);
out:
fib_release_info(fi);
return err;
@ -595,7 +602,7 @@ static int fn_hash_delete(struct fib_table *tb, struct fib_config *cfg)
if (fa->fa_state & FA_S_ACCESSED)
rt_cache_flush(-1);
fn_free_alias(fa);
fn_free_alias(fa, f);
if (kill_fn) {
fn_free_node(f);
fz->fz_nent--;
@ -631,7 +638,7 @@ static int fn_flush_list(struct fn_zone *fz, int idx)
fib_hash_genid++;
write_unlock_bh(&fib_hash_lock);
fn_free_alias(fa);
fn_free_alias(fa, f);
found++;
}
}
@ -750,10 +757,10 @@ static int fn_hash_dump(struct fib_table *tb, struct sk_buff *skb, struct netlin
void __init fib_hash_init(void)
{
fn_hash_kmem = kmem_cache_create("ip_fib_hash", sizeof(struct fib_node),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
0, SLAB_PANIC, NULL);
fn_alias_kmem = kmem_cache_create("ip_fib_alias", sizeof(struct fib_alias),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
0, SLAB_PANIC, NULL);
}

4
net/ipv4/fib_lookup.h
View File

@ -7,12 +7,14 @@
struct fib_alias {
struct list_head fa_list;
struct rcu_head rcu;
struct fib_info *fa_info;
u8 fa_tos;
u8 fa_type;
u8 fa_scope;
u8 fa_state;
#ifdef CONFIG_IP_FIB_TRIE
struct rcu_head rcu;
#endif
};
#define FA_S_ACCESSED 0x01