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Date: Tue, 15 Jan 2008 07:12:07 +0100
From: Eric Dumazet <dada1@...mosbay.com>
To: Stephen Hemminger <stephen.hemminger@...tta.com>
CC: David Miller <davem@...emloft.net>, robert.olsson@....uu.se,
netdev@...r.kernel.org
Subject: Re: [RFC 6/6] fib_trie: combine leaf and info
Stephen Hemminger a écrit :
> Combine the prefix information and the leaf together into one
> allocation. This is furthur simplified by converting the hlist
> into a simple bitfield.
>
> Signed-off-by: Stephen Hemminger <stephen.hemminger@...tta.com>
>
> This patch is experimental (ie it boots and loads routes), but
> is slower for the 163,000 route dump test.
>
Its also very memory expensive. That was not Robert suggestion I believe.
Its suggestion is to embedd one info into each leaves.
Please find attached to this mail a preliminary and incomplete patch I wrote
this morning before coffee :), to get the idea.
Before patching this file, maybe we should first do a cleanup (checkpatch.pl
and obvious modern style formating :) )
> ---
> net/ipv4/fib_trie.c | 165 ++++++++++++++++++++--------------------------------
> 1 file changed, 65 insertions(+), 100 deletions(-)
>
> --- a/net/ipv4/fib_trie.c 2008-01-14 18:37:51.000000000 -0800
> +++ b/net/ipv4/fib_trie.c 2008-01-14 20:57:12.000000000 -0800
> @@ -50,10 +50,9 @@
> * Patrick McHardy <kaber@...sh.net>
> */
>
> -#define VERSION "0.408"
> +#define VERSION "0.409"
> +
>
> -#include <asm/uaccess.h>
> -#include <asm/system.h>
> #include <linux/bitops.h>
> #include <linux/types.h>
> #include <linux/kernel.h>
> @@ -80,6 +79,8 @@
> #include <net/tcp.h>
> #include <net/sock.h>
> #include <net/ip_fib.h>
> +#include <asm/bitops.h>
> +
> #include "fib_lookup.h"
>
> #define MAX_STAT_DEPTH 32
> @@ -101,20 +102,24 @@ struct node {
> t_key key;
> };
>
> +struct leaf_info {
> + struct list_head falh;
> +};
> +
> +#define INFO_SIZE 33
> +/* NB: bitmap is in reverse order, so that find_first returns largest prefix */
> +#define PLEN2BIT(x) (INFO_SIZE - (x))
> +
> struct leaf {
> unsigned long parent;
> t_key key;
> - struct hlist_head list;
> struct rcu_head rcu;
> -};
>
> -struct leaf_info {
> - struct hlist_node hlist;
> - struct rcu_head rcu;
> - int plen;
> - struct list_head falh;
> + unsigned long bitmap[INFO_SIZE / BITS_PER_LONG + 1];
> + struct leaf_info info[INFO_SIZE];
> };
>
> +
> struct tnode {
> unsigned long parent;
> t_key key;
> @@ -321,16 +326,6 @@ static void __leaf_free_rcu(struct rcu_h
> kmem_cache_free(trie_leaf_kmem, leaf);
> }
>
> -static void __leaf_info_free_rcu(struct rcu_head *head)
> -{
> - kfree(container_of(head, struct leaf_info, rcu));
> -}
> -
> -static inline void free_leaf_info(struct leaf_info *leaf)
> -{
> - call_rcu(&leaf->rcu, __leaf_info_free_rcu);
> -}
> -
> static struct tnode *tnode_alloc(size_t size)
> {
> struct page *pages;
> @@ -371,21 +366,37 @@ static struct leaf *leaf_new(void)
> struct leaf *l = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
> if (l) {
> l->parent = T_LEAF;
> - INIT_HLIST_HEAD(&l->list);
> + bitmap_zero(l->bitmap, INFO_SIZE);
> }
> return l;
> }
>
> -static struct leaf_info *leaf_info_new(int plen)
> +static inline struct leaf_info *find_leaf_info(struct leaf *l, int plen)
> {
> - struct leaf_info *li = kmalloc(sizeof(struct leaf_info), GFP_KERNEL);
> - if (li) {
> - li->plen = plen;
> - INIT_LIST_HEAD(&li->falh);
> - }
> + return test_bit(PLEN2BIT(plen), l->bitmap) ? &l->info[plen] : NULL;
> +}
> +
> +static struct leaf_info *set_leaf_info(struct leaf *l, int plen)
> +{
> + struct leaf_info *li = &l->info[plen];
> +
> + INIT_LIST_HEAD(&li->falh);
> + set_bit(PLEN2BIT(plen), l->bitmap);
> +
> return li;
> }
>
> +static inline void clear_leaf_info(struct leaf *l, int plen)
> +{
> + smp_mb__before_clear_bit();
> + clear_bit(PLEN2BIT(plen), &l->bitmap);
> +}
> +
> +static inline int leaf_info_empty(const struct leaf *l)
> +{
> + return find_first_bit(l->bitmap, INFO_SIZE) >= INFO_SIZE;
> +}
> +
> static struct tnode* tnode_new(t_key key, int pos, int bits)
> {
> size_t sz = sizeof(struct tnode) + (sizeof(struct node *) << bits);
> @@ -876,20 +887,6 @@ nomem:
>
> /* readside must use rcu_read_lock currently dump routines
> via get_fa_head and dump */
> -
> -static struct leaf_info *find_leaf_info(struct leaf *l, int plen)
> -{
> - struct hlist_head *head = &l->list;
> - struct hlist_node *node;
> - struct leaf_info *li;
> -
> - hlist_for_each_entry_rcu(li, node, head, hlist)
> - if (li->plen == plen)
> - return li;
> -
> - return NULL;
> -}
> -
> static inline struct list_head * get_fa_head(struct leaf *l, int plen)
> {
> struct leaf_info *li = find_leaf_info(l, plen);
> @@ -900,26 +897,6 @@ static inline struct list_head * get_fa_
> return &li->falh;
> }
>
> -static void insert_leaf_info(struct hlist_head *head, struct leaf_info *new)
> -{
> - struct leaf_info *li = NULL, *last = NULL;
> - struct hlist_node *node;
> -
> - if (hlist_empty(head)) {
> - hlist_add_head_rcu(&new->hlist, head);
> - } else {
> - hlist_for_each_entry(li, node, head, hlist) {
> - if (new->plen > li->plen)
> - break;
> -
> - last = li;
> - }
> - if (last)
> - hlist_add_after_rcu(&last->hlist, &new->hlist);
> - else
> - hlist_add_before_rcu(&new->hlist, &li->hlist);
> - }
> -}
>
> /* rcu_read_lock needs to be hold by caller from readside */
>
> @@ -993,6 +970,8 @@ static struct list_head *fib_insert_node
> pos = 0;
> n = t->trie;
>
> + pr_debug("fib_insert_node: %x/%d\n", key, plen);
> +
> /* If we point to NULL, stop. Either the tree is empty and we should
> * just put a new leaf in if, or we have reached an empty child slot,
> * and we should just put our new leaf in that.
> @@ -1038,13 +1017,9 @@ static struct list_head *fib_insert_node
>
> if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key)) {
> l = (struct leaf *) n;
> - li = leaf_info_new(plen);
> -
> - if (!li)
> - return NULL;
> -
> + li = set_leaf_info(l, plen);
> fa_head = &li->falh;
> - insert_leaf_info(&l->list, li);
> +
> goto done;
> }
> l = leaf_new();
> @@ -1053,15 +1028,8 @@ static struct list_head *fib_insert_node
> return NULL;
>
> l->key = key;
> - li = leaf_info_new(plen);
> -
> - if (!li) {
> - tnode_free((struct tnode *) l);
> - return NULL;
> - }
> -
> + li = set_leaf_info(l, plen);
> fa_head = &li->falh;
> - insert_leaf_info(&l->list, li);
>
> if (t->trie && n == NULL) {
> /* Case 2: n is NULL, and will just insert a new leaf */
> @@ -1091,7 +1059,6 @@ static struct list_head *fib_insert_node
> }
>
> if (!tn) {
> - free_leaf_info(li);
> tnode_free((struct tnode *) l);
> return NULL;
> }
> @@ -1119,7 +1086,7 @@ static struct list_head *fib_insert_node
>
> rcu_assign_pointer(t->trie, trie_rebalance(t, tp));
> done:
> - return fa_head;
> + return &li->falh;
> }
>
> /*
> @@ -1281,14 +1248,14 @@ static int check_leaf(struct trie *t, st
> t_key key, const struct flowi *flp,
> struct fib_result *res)
> {
> - struct leaf_info *li;
> - struct hlist_head *hhead = &l->list;
> - struct hlist_node *node;
> + int bit;
>
> - hlist_for_each_entry_rcu(li, node, hhead, hlist) {
> - int err;
> - int plen = li->plen;
> + /* need find highest prefix */
> + for_each_bit(bit, l->bitmap, INFO_SIZE) {
> + int plen = PLEN2BIT(bit);
> + struct leaf_info *li = &l->info[plen];
> __be32 mask = inet_make_mask(plen);
> + int err;
>
> if (l->key != (key & ntohl(mask)))
> continue;
> @@ -1622,12 +1589,10 @@ static int fn_trie_delete(struct fib_tab
>
> list_del_rcu(&fa->fa_list);
>
> - if (list_empty(fa_head)) {
> - hlist_del_rcu(&li->hlist);
> - free_leaf_info(li);
> - }
> + if (list_empty(fa_head))
> + clear_leaf_info(l, plen);
>
> - if (hlist_empty(&l->list))
> + if (leaf_info_empty(l))
> trie_leaf_remove(t, key);
>
> if (fa->fa_state & FA_S_ACCESSED)
> @@ -1659,18 +1624,17 @@ static int trie_flush_list(struct trie *
> static int trie_flush_leaf(struct trie *t, struct leaf *l)
> {
> int found = 0;
> - struct hlist_head *lih = &l->list;
> - struct hlist_node *node, *tmp;
> - struct leaf_info *li = NULL;
> + int bit;
>
> - hlist_for_each_entry_safe(li, node, tmp, lih, hlist) {
> + for_each_bit(bit, l->bitmap, INFO_SIZE) {
> + int plen = PLEN2BIT(bit);
> + struct leaf_info *li = &l->info[plen];
> found += trie_flush_list(t, &li->falh);
>
> - if (list_empty(&li->falh)) {
> - hlist_del_rcu(&li->hlist);
> - free_leaf_info(li);
> - }
> + if (list_empty(&li->falh))
> + clear_leaf_info(l, plen);
> }
> +
> return found;
> }
>
> @@ -1746,12 +1710,12 @@ static int fn_trie_flush(struct fib_tabl
> for (h = 0; (l = nextleaf(t, l)) != NULL; h++) {
> found += trie_flush_leaf(t, l);
>
> - if (ll && hlist_empty(&ll->list))
> + if (ll && leaf_info_empty(ll))
> trie_leaf_remove(t, ll->key);
> ll = l;
> }
>
> - if (ll && hlist_empty(&ll->list))
> + if (ll && leaf_info_empty(ll))
> trie_leaf_remove(t, ll->key);
>
> pr_debug("trie_flush found=%d\n", found);
> @@ -2428,10 +2392,11 @@ static int fib_route_seq_show(struct seq
>
> if (iter->trie == iter->trie_local)
> return 0;
> +
> if (IS_TNODE(l))
> return 0;
>
> - for (i=32; i>=0; i--) {
> + for (i = 32; i >= 0; i--) {
> struct leaf_info *li = find_leaf_info(l, i);
> struct fib_alias *fa;
> __be32 mask, prefix;
> @@ -2439,7 +2404,7 @@ static int fib_route_seq_show(struct seq
> if (!li)
> continue;
>
> - mask = inet_make_mask(li->plen);
> + mask = inet_make_mask(i);
> prefix = htonl(l->key);
>
> list_for_each_entry_rcu(fa, &li->falh, fa_list) {
> --
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