netdev - Re: [RFC 6/6] fib_trie: combine leaf and info

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Date:	Tue, 15 Jan 2008 18:25:44 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Robert Olsson <Robert.Olsson@...a.slu.se>
Cc:	Stephen Hemminger <stephen.hemminger@...tta.com>,
	David Miller <davem@...emloft.net>, robert.olsson@....uu.se,
	netdev@...r.kernel.org
Subject: Re: [RFC 6/6] fib_trie: combine leaf and info

On Tue, 15 Jan 2008 17:44:47 +0100
Robert Olsson <Robert.Olsson@...a.slu.se> wrote:

> 
> Stephen Hemminger writes:
> 
>  > Okay, I would rather see the leaf_info explicit inside the leaf, also
>  > your scheme probably breaks if I add two prefixes and then delete the first.
>  > Let me have a go at it.
> 
>  I took Eric's patch a bit further... 
>  
>  Support for delete and dump is needed before any testing at all
>  and maybe some macro for checking and setting FP-leaf's
> 
>  Cheers.
> 					--ro
> 
> 
> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> index 6dab753..f5b276c 100644
> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
> @@ -97,22 +97,32 @@ typedef unsigned int t_key;
>  #define IS_LEAF(n) (n->parent & T_LEAF)
>  
>  struct node {
> -	unsigned long parent;
> -	t_key key;
> +	unsigned long		parent;
> +	t_key			key;
>  };
>  
>  struct leaf {
> -	unsigned long parent;
> -	t_key key;
> -	struct hlist_head list;
> -	struct rcu_head rcu;
> +	unsigned long		parent;
> +	t_key			key;
> +	/*
> +	 * Because we often have only one info per leaf, we embedd one here
> +	 * to save some space and speedup lookups (sharing cache line)
> +	 * a sort of fastpatch leaf (FP-leaf) this indicated a negative of
> +	 * plen_iinfo.
> +	 * Note : not inside a structure so that we dont have holes on 64bit 
> +	 */
> +	int 			plen_iinfo;
> +	struct list_head	falh_iinfo;

yep, I renamed them to einfo_plen & einfo_falh

> +
> +	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;
> +	struct hlist_node	hlist;
> +	int			plen;
> +	struct list_head	falh;
> +	struct rcu_head		rcu;
>  };
>  
>  struct tnode {
> @@ -364,11 +374,13 @@ static inline void tnode_free(struct tnode *tn)
>  		call_rcu(&tn->rcu, __tnode_free_rcu);
>  }
>  
> -static struct leaf *leaf_new(void)
> +static struct leaf *leaf_new(int plen)
>  {
>  	struct leaf *l = kmalloc(sizeof(struct leaf),  GFP_KERNEL);
>  	if (l) {
>  		l->parent = T_LEAF;
> +		l->plen_iinfo = plen;
> +		INIT_LIST_HEAD(&l->falh_iinfo);
>  		INIT_HLIST_HEAD(&l->list);
>  	}
>  	return l;
> @@ -890,7 +902,16 @@ static struct leaf_info *find_leaf_info(struct leaf *l, int plen)
>  
>  static inline struct list_head * get_fa_head(struct leaf *l, int plen)
>  {
> -	struct leaf_info *li = find_leaf_info(l, plen);
> +	struct leaf_info *li;
> +
> +	if (l->plen_iinfo >= 0) {
> +		if(l->plen_iinfo == plen)
> +			return &l->falh_iinfo;
> +		else
> +			return NULL;
> +	}

So you think that a leaf cannot have 2 infos, one 'embeded' and one in the list ?


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