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

From: Jarek Poplawski <[email-masked]>
Date: Sat, 27 Jun 2009 22:51:23 +0200

On Sat, Jun 27, 2009 at 09:20:57PM +0200, Jarek Poplawski wrote:
...
> Then these settable thresholds might be more useful here than memory
> fixes, but here is some idea to try handle this automatically within
> some limits. The patch below increases inflate_threshold_root (only)
> up to ~50% of its initial value if needed, and should be able to go
> back sometimes.
> 
> Pawel and Jorge, could you try this? (It applies to 2.6.29 too, with
> some offsets.)

A tiny adjustment in the last if...

Jarek P.
--- (take 2)

 net/ipv4/fib_trie.c |   23 ++++++++++++++++-------
 1 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 012cf5a..1dc1bb4 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -318,6 +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)
@@ -602,7 +603,8 @@ static struct node *resize(struct trie *t, struct tnode *tn)
 	/* 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;
 
@@ -626,15 +628,22 @@ static struct node *resize(struct trie *t, struct tnode *tn)
 	}
 
 	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);