netdev - Re: [PATCH net-2.6] Re: rib_trie / Fix inflate_threshold

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Message-ID: <20090705173208.GB19477@ami.dom.local>
Date:	Sun, 5 Jul 2009 19:32:08 +0200
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Paweł Staszewski <pstaszewski@...are.pl>
Cc:	Linux Network Development list <netdev@...r.kernel.org>,
	Robert Olsson <robert@...ur.slu.se>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH net-2.6] Re: rib_trie / Fix inflate_threshold_root.
	Now=15 size=11 bits

On Sun, Jul 05, 2009 at 06:20:03PM +0200, Jarek Poplawski wrote:
> On Sun, Jul 05, 2009 at 02:30:03AM +0200, Paweł Staszewski wrote:
> > Oh
> >
> > I forgot - please Jarek give me patch with sync rcu and i will make test  
> > on preempt kernel
> 
> Probably non-preempt kernel might need something like this more, but
> comparing is always interesting. This patch is based on Paul's
> suggestion (I hope).

Hold on ;-) Here is something even better... Syncing after 128 pages
might be still too slow, so here is a higher initial value, 1000, plus
you can change this while testing in:

/sys/module/fib_trie/parameters/sync_pages

It would be interesting to find the lowest acceptable value.

Jarek P.
---> (synchronize take 8; apply on top of the 2.6.29.x with the last
 	all-in-one patch, or net-2.6)

 net/ipv4/fib_trie.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 00a54b2..decc8d0 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -71,6 +71,7 @@
 #include <linux/netlink.h>
 #include <linux/init.h>
 #include <linux/list.h>
+#include <linux/moduleparam.h>
 #include <net/net_namespace.h>
 #include <net/ip.h>
 #include <net/protocol.h>
@@ -164,6 +165,10 @@ 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 size_t tnode_free_size;
+
+static int sync_pages __read_mostly = 1000;
+module_param(sync_pages, int, 0640);
 
 static struct kmem_cache *fn_alias_kmem __read_mostly;
 static struct kmem_cache *trie_leaf_kmem __read_mostly;
@@ -393,6 +398,8 @@ static void tnode_free_safe(struct tnode *tn)
 	BUG_ON(IS_LEAF(tn));
 	tn->tnode_free = tnode_free_head;
 	tnode_free_head = tn;
+	tnode_free_size += sizeof(struct tnode) +
+			   (sizeof(struct node *) << tn->bits);
 }
 
 static void tnode_free_flush(void)
@@ -404,6 +411,11 @@ static void tnode_free_flush(void)
 		tn->tnode_free = NULL;
 		tnode_free(tn);
 	}
+
+	if (tnode_free_size >= PAGE_SIZE * sync_pages) {
+		tnode_free_size = 0;
+		synchronize_rcu();
+	}
 }
 
 static struct leaf *leaf_new(void)
--
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