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Message-ID: <4A4BE06F.3090608@itcare.pl>
Date: Thu, 02 Jul 2009 00:17:19 +0200
From: Paweł Staszewski <pstaszewski@...are.pl>
To: Jarek Poplawski <jarkao2@...il.com>
CC: Linux Network Development list <netdev@...r.kernel.org>,
Robert Olsson <robert@...ur.slu.se>
Subject: Re: [PATCH net-2.6] Re: rib_trie / Fix inflate_threshold_root. Now=15
size=11 bits
Jarek Poplawski pisze:
> On Wed, Jul 01, 2009 at 10:13:33AM +0000, Jarek Poplawski wrote:
>
>> On Wed, Jul 01, 2009 at 11:43:04AM +0200, Paweł Staszewski wrote:
>> ...
>>
>>> Yes on on previous patches there was / no warnings / no oopses or lockups
>>>
>>> But now i apply this patch and i make more testing.
>>> First boot with start of bgpd and - traffic is not forwarded
>>> So i start to search and make only some routes (static without bgpd)
>>> thru this host
>>> And all is working for this host when i make all by static routes.
>>>
>>> So i change a little my bgp configuration and make default route to only
>>> one of my iBGP peers and start bgpd process
>>> All is working and what is weird is number of routes in kernel table.
>>> Kernel is learning routes from bgpd but very slowly - really very slowly.
>>>
>> Pawel, this is really very helpful! So, this is (probably) only about
>> timing, not wrong memory freeing. On the other hand this test was only
>> for inserts. Btw., if you didn't start the second test, you can skip
>> it. I have to rethink this.
>>
>
> So, after your findings I'm about to recommend sending to -stable
> 3 patches from net-2.6, with additional lowering of threshold_root
> settings, but it would be nice if you could give it a try with
> CONFIG_PREEMPT instead of CONFIG_PREEMPT_NONE (if it doesn't break
> your other apps!) It is expected to work this time...;-) Maybe a
> bit slower.
>
>
Patch applied to 2.6.29.5 with CONFIG_PREEMPT_NONE
And working :)
fib_triestats in attached file
I think I can test it with PREEMPT enabled but first i must make some
other tests of my apps that are on server.
Regards
Paweł Staszewski
> Thanks,
> Jarek P.
> --------> (all-in-one preempt fixes to apply with vanilla 2.6.29.x)
>
> diff -Nurp a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> --- a/net/ipv4/fib_trie.c 2009-07-01 06:17:08.000000000 +0000
> +++ b/net/ipv4/fib_trie.c 2009-07-01 10:43:44.000000000 +0000
> @@ -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;
> @@ -313,8 +316,8 @@ static inline void check_tnode(const str
>
> 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 const int halve_threshold_root = 15;
> +static const int inflate_threshold_root = 25;
>
>
> static void __alias_free_mem(struct rcu_head *head)
> @@ -385,6 +388,24 @@ 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 +516,7 @@ 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 +530,7 @@ static struct node *resize(struct trie *
>
> /* compress one level */
> node_set_parent(n, NULL);
> - tnode_free(tn);
> + tnode_free_safe(tn);
> return n;
> }
> /*
> @@ -670,7 +691,7 @@ 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 +777,7 @@ 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 +822,9 @@ 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 +906,7 @@ 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 +1004,14 @@ 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));
> @@ -999,6 +1022,10 @@ static struct node *trie_rebalance(struc
>
> tp = node_parent((struct node *) tn);
> if (!tp)
> + rcu_assign_pointer(t->trie, (struct node *)tn);
> +
> + tnode_free_flush();
> + if (!tp)
> break;
> tn = tp;
> }
> @@ -1007,7 +1034,10 @@ static struct node *trie_rebalance(struc
> if (IS_TNODE(tn))
> tn = (struct tnode *)resize(t, (struct tnode *)tn);
>
> - return (struct node *)tn;
> + rcu_assign_pointer(t->trie, (struct node *)tn);
> + tnode_free_flush();
> +
> + return;
> }
>
> /* only used from updater-side */
> @@ -1155,7 +1185,7 @@ 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 +1605,7 @@ 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);
>
>
>
>
View attachment "fib_triestats.txt" of type "text/plain" (926 bytes)
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