On Tue, 15 Jan 2008 10:15:43 -0800
Stephen Hemminger <[EMAIL PROTECTED]> wrote:
> On Tue, 15 Jan 2008 19:10:31 +0100
> Eric Dumazet <[EMAIL PROTECTED]> wrote:
>
> > On Tue, 15 Jan 2008 09:47:53 -0800
> > Stephen Hemminger <[EMAIL PROTECTED]> wrote:
> >
> > > This is how I did it:
> > >
> > > --- a/net/ipv4/fib_trie.c 2008-01-15 09:14:53.000000000 -0800
> > > +++ b/net/ipv4/fib_trie.c 2008-01-15 09:21:48.000000000 -0800
> > > @@ -101,13 +101,6 @@ struct node {
> > > t_key key;
> > > };
> > >
> > > -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;
> > > @@ -115,6 +108,13 @@ struct leaf_info {
> > > struct list_head falh;
> > > };
> > >
> > > +struct leaf {
> > > + unsigned long parent;
> > > + t_key key;
> > > + struct hlist_head list;
> > > + struct rcu_head rcu;
> > > +};
> >
> > I like this :)
> >
> > Your design is clean, but we waste some space (rcu in leaf_info
> > "included"), we probably can do a litle bit better
> > (moving rcu at the end of leaf_info, and kmem_cache_create("ip_fib_trie",
> > sizeof(struct leaf) + sizeof(struct_leaf_info) - sizeof(struct rcu_head))
> >
> >
> > > - trie_leaf_kmem = kmem_cache_create("ip_fib_trie", sizeof(struct leaf),
> > > + trie_leaf_kmem = kmem_cache_create("ip_fib_trie",
> > > + sizeof(struct leaf) + sizeof(struct
> > > leaf_info),
> > > 0, SLAB_PANIC, NULL);
> > > }
> > >
> > >
> >
> > Thank you
>
> Having multiple RCU links is a waste. I started on code that just splice's the
> leaf_info's off to a free_list and then do a mass free after and RCU barrier.
>
> For the normal case of just freeing a leaf, it could just walk the chain
> in the RCU free of the leaf.
Well, If you take this path, we can also copy the leaf itself, and
just use a variable size array of infos[], no more list, and maximal locality
kmalloc(sizeof(leaf) + nb_infos * sizeof(info))
(Still we can use a kmem cache for nb_infos=1 leaves)
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