Subject: Re: rib_trie / Fix inflate_threshold_root. Now=15 size=11 bits

From: Paweł Staszewski <[email-masked]>
Date: Sun, 28 Jun 2009 17:32:18 +0200

After 18 hours from apply first Jarek patch i have no info about Fix 
inflate_threshold_root
even if i make: "clear ip bgp *" on router
So i change Jarek patch from previous to this new one for test and we 
will see ...

Regards
Pawel Staszewski

Jarek Poplawski pisze:
> On Sun, Jun 28, 2009 at 01:04:51PM +0200, Robert Olsson wrote:
> ...
>   
>>  The memory patches and "manual RCU" are also interesting to address
>>  the case with PREEMTP's.
>>     
>
> Since 2.6.29 looks like prefered here, and there were a lot of takes
> in this thread, I attach below a combined all-in-one patch including:
> - 2.6.29 -> 2.6.30 preemption disable patch
> - 2 RCU vs. preemption fixes from 2.6.31-rc
> - "manual RCU" patch to force vfree/kfree before root's resize (take 3)
> - "automatic" inflate_threshold_root fix (take 2)
>
> Thanks,
> Jarek P.
>
> --- (for 2.6.29.x or even .28 or .27; any testing appreciated)
>
> diff -Nurp a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> --- a/net/ipv4/fib_trie.c	2009-06-27 20:25:06.000000000 +0200
> +++ b/net/ipv4/fib_trie.c	2009-06-28 15:45:02.000000000 +0200
> @@ -123,6 +123,7 @@ struct tnode {
>  	union {
>  		struct rcu_head rcu;
>  		struct work_struct work;
> +		struct tnode *tnode_free;
>  	};
>  	struct node *child[0];
>  };
> @@ -161,6 +162,8 @@ static void tnode_put_child_reorg(struct
>  static struct node *resize(struct trie *t, struct tnode *tn);
>  static struct tnode *inflate(struct trie *t, struct tnode *tn);
>  static struct tnode *halve(struct trie *t, struct tnode *tn);
> +/* tnodes to free after resize(); protected by RTNL */
> +static struct tnode *tnode_free_head;
>  
>  static struct kmem_cache *fn_alias_kmem __read_mostly;
>  static struct kmem_cache *trie_leaf_kmem __read_mostly;
> @@ -315,6 +318,7 @@ static const int halve_threshold = 25;
>  static const int inflate_threshold = 50;
>  static const int halve_threshold_root = 8;
>  static const int inflate_threshold_root = 15;
> +static int inflate_threshold_root_fix;
>  
>  
>  static void __alias_free_mem(struct rcu_head *head)
> @@ -363,6 +367,17 @@ static void __tnode_vfree(struct work_st
>  	vfree(tn);
>  }
>  
> +static void __tnode_free(struct tnode *tn)
> +{
> +	size_t size = sizeof(struct tnode) +
> +		      (sizeof(struct node *) << tn->bits);
> +
> +	if (size <= PAGE_SIZE)
> +		kfree(tn);
> +	else
> +		vfree(tn);
> +}
> +
>  static void __tnode_free_rcu(struct rcu_head *head)
>  {
>  	struct tnode *tn = container_of(head, struct tnode, rcu);
> @@ -385,6 +400,24 @@ static inline void tnode_free(struct tno
>  		call_rcu(&tn->rcu, __tnode_free_rcu);
>  }
>  
> +static void tnode_free_safe(struct tnode *tn)
> +{
> +	BUG_ON(IS_LEAF(tn));
> +	tn->tnode_free = tnode_free_head;
> +	tnode_free_head = tn;
> +}
> +
> +static void tnode_free_flush(void)
> +{
> +	struct tnode *tn;
> +
> +	while ((tn = tnode_free_head)) {
> +		tnode_free_head = tn->tnode_free;
> +		tn->tnode_free = NULL;
> +		__tnode_free(tn);
> +	}
> +}
> +
>  static struct leaf *leaf_new(void)
>  {
>  	struct leaf *l = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
> @@ -495,7 +528,7 @@ static struct node *resize(struct trie *
>  
>  	/* No children */
>  	if (tn->empty_children == tnode_child_length(tn)) {
> -		tnode_free(tn);
> +		tnode_free_safe(tn);
>  		return NULL;
>  	}
>  	/* One child */
> @@ -509,7 +542,7 @@ static struct node *resize(struct trie *
>  
>  			/* compress one level */
>  			node_set_parent(n, NULL);
> -			tnode_free(tn);
> +			tnode_free_safe(tn);
>  			return n;
>  		}
>  	/*
> @@ -581,7 +614,8 @@ static struct node *resize(struct trie *
>  	/* Keep root node larger  */
>  
>  	if (!tn->parent)
> -		inflate_threshold_use = inflate_threshold_root;
> +		inflate_threshold_use = inflate_threshold_root +
> +					inflate_threshold_root_fix;
>  	else
>  		inflate_threshold_use = inflate_threshold;
>  
> @@ -605,15 +639,22 @@ static struct node *resize(struct trie *
>  	}
>  
>  	if (max_resize < 0) {
> -		if (!tn->parent)
> -			pr_warning("Fix inflate_threshold_root."
> -				   " Now=%d size=%d bits\n",
> -				   inflate_threshold_root, tn->bits);
> -		else
> +		if (!tn->parent) {
> +			if (inflate_threshold_root_fix * 2 <
> +			    inflate_threshold_root)
> +				inflate_threshold_root_fix++;
> +			else
> +				pr_warning("Fix inflate_threshold_root."
> +					   " Now=%d size=%d bits fix=%d\n",
> +					   inflate_threshold_root, tn->bits,
> +					   inflate_threshold_root_fix);
> +		} else {
>  			pr_warning("Fix inflate_threshold."
>  				   " Now=%d size=%d bits\n",
>  				   inflate_threshold, tn->bits);
> -	}
> +		}
> +	} else if (max_resize > 4 && !tn->parent && inflate_threshold_root_fix)
> +		inflate_threshold_root_fix--;
>  
>  	check_tnode(tn);
>  
> @@ -670,7 +711,7 @@ static struct node *resize(struct trie *
>  			/* compress one level */
>  
>  			node_set_parent(n, NULL);
> -			tnode_free(tn);
> +			tnode_free_safe(tn);
>  			return n;
>  		}
>  
> @@ -756,7 +797,7 @@ static struct tnode *inflate(struct trie
>  			put_child(t, tn, 2*i, inode->child[0]);
>  			put_child(t, tn, 2*i+1, inode->child[1]);
>  
> -			tnode_free(inode);
> +			tnode_free_safe(inode);
>  			continue;
>  		}
>  
> @@ -801,9 +842,9 @@ static struct tnode *inflate(struct trie
>  		put_child(t, tn, 2*i, resize(t, left));
>  		put_child(t, tn, 2*i+1, resize(t, right));
>  
> -		tnode_free(inode);
> +		tnode_free_safe(inode);
>  	}
> -	tnode_free(oldtnode);
> +	tnode_free_safe(oldtnode);
>  	return tn;
>  nomem:
>  	{
> @@ -885,7 +926,7 @@ static struct tnode *halve(struct trie *
>  		put_child(t, newBinNode, 1, right);
>  		put_child(t, tn, i/2, resize(t, newBinNode));
>  	}
> -	tnode_free(oldtnode);
> +	tnode_free_safe(oldtnode);
>  	return tn;
>  nomem:
>  	{
> @@ -983,12 +1024,14 @@ fib_find_node(struct trie *t, u32 key)
>  	return NULL;
>  }
>  
> -static struct node *trie_rebalance(struct trie *t, struct tnode *tn)
> +static void trie_rebalance(struct trie *t, struct tnode *tn)
>  {
>  	int wasfull;
> -	t_key cindex, key = tn->key;
> +	t_key cindex, key;
>  	struct tnode *tp;
>  
> +	key = tn->key;
> +
>  	while (tn != NULL && (tp = node_parent((struct node *)tn)) != NULL) {
>  		cindex = tkey_extract_bits(key, tp->pos, tp->bits);
>  		wasfull = tnode_full(tp, tnode_get_child(tp, cindex));
> @@ -1003,11 +1046,22 @@ static struct node *trie_rebalance(struc
>  		tn = tp;
>  	}
>  
> +	if (tnode_free_head) {
> +		synchronize_rcu();
> +		tnode_free_flush();
> +	}
> +
>  	/* Handle last (top) tnode */
> -	if (IS_TNODE(tn))
> +	if (IS_TNODE(tn)) {
>  		tn = (struct tnode *)resize(t, (struct tnode *)tn);
> +		rcu_assign_pointer(t->trie, (struct node *)tn);
> +		synchronize_rcu();
> +		tnode_free_flush();
> +	} else {
> +		rcu_assign_pointer(t->trie, (struct node *)tn);
> +	}
>  
> -	return (struct node *)tn;
> +	return;
>  }
>  
>  /* only used from updater-side */
> @@ -1155,7 +1209,7 @@ static struct list_head *fib_insert_node
>  
>  	/* Rebalance the trie */
>  
> -	rcu_assign_pointer(t->trie, trie_rebalance(t, tp));
> +	trie_rebalance(t, tp);
>  done:
>  	return fa_head;
>  }
> @@ -1575,7 +1629,7 @@ static void trie_leaf_remove(struct trie
>  	if (tp) {
>  		t_key cindex = tkey_extract_bits(l->key, tp->pos, tp->bits);
>  		put_child(t, (struct tnode *)tp, cindex, NULL);
> -		rcu_assign_pointer(t->trie, trie_rebalance(t, tp));
> +		trie_rebalance(t, tp);
>  	} else
>  		rcu_assign_pointer(t->trie, NULL);
>  
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to [email-masked]
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
>