Subject: Re: [PATCH net-2.6] Re: rib_trie / Fix inflate_threshold_root. Now=15 size=11 bits

From: Paweł Staszewski <[email-masked]>
Date: Wed, 08 Jul 2009 00:56:13 +0200

Jarek Poplawski pisze:
> On Mon, Jul 06, 2009 at 01:53:49AM +0200, Paweł Staszewski wrote:
> ...
>   
>> So i make tests with changing sync_pages
>> And
>>
>> ####################################
>> sync_pages: 64
>> total size reach maximum in 17sec
>>     
> ...
>   
>> ######################################
>> sync_pages: 128
>> Fib trie Total size reach max in 14sec
>>     
> ...
>   
>> #########################################
>> sync_pages: 256
>> hmm no difference also in 10sec
>>     
>
> 14 == 10!? ;-)
> ...
>   
>> And with sync_pages higher that 256 time of filling kernel routes is the  
>> same approx 10sec.
>>     
>
> Hmm... So, it's better than I expected; syncing after 128 or 256 pages
> could be quite reasonable. But then it would be interesting to find
> out if with such a safety we could go back to more aggressive values
> for possibly better performance. So here is 'the same' patch (so the
> previous, take 8, should be reverted), but with additional possibility
> to change:
> /sys/module/fib_trie/parameters/inflate_threshold_root
>
> I guess, you could try e.g. if: sync_pages 256, inflate_threshold_root 15
> can give faster lookups (or lower cpu loads); with this these inflate
> warnings could be back btw.; or maybe you'll find something in between
> like inflate_threshold_root 20 is optimal for you. (I think it should be
> enough to try this only for PREEMPT_NONE unless you have spare time ;-)
>
> Thanks,
> Jarek P.
> ---> (synchronize take 9; apply on top of the 2.6.29.x with the last
>   	all-in-one patch, or net-2.6)
>
>   

Applied to 2.6.29.5 preempt/no-preempt and tested: - with preempt i make 
only one test with sync_pages = 256 to check that is working :)

So here are some tests for different sync_pages size.

echo 1 > /sys/module/fib_trie/parameters/sync_pages
I stop count after 1minute - total size still rising :)

echo 2 > /sys/module/fib_trie/parameters/sync_pages
Total size in fib_triestats reach maximum in 33sec

echo 3 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 31sec

echo 4 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 23sec

echo 8 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 17sec

echo 16 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 14 sec

echo 32 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 14 sec

So i see in prev tests i make something wrong in time counting
So i modify test script and make tests again:

echo 64 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 13 sec

echo 128 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 10 sec

echo 256 > /sys/module/fib_trie/parameters/sync_pages
Total size reach max in 10 sec

And for sync_paqges >256 time for propagating routes is always 10sec.

Also today i have many messages in dmesg like this:
Fix inflate_threshold_root. Now=25 size=11 bits
:)

And after tune :
/sys/module/fib_trie/parameters/inflate_threshold_root
no more info :)

Regards
Paweł Staszewski

>  net/ipv4/fib_trie.c |   18 ++++++++++++++++--
>  1 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> index 00a54b2..e8fca11 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;
> @@ -316,9 +321,11 @@ static inline void check_tnode(const struct tnode *tn)
>  
>  static const int halve_threshold = 25;
>  static const int inflate_threshold = 50;
> -static const int halve_threshold_root = 15;
> -static const int inflate_threshold_root = 25;
>  
> +static int inflate_threshold_root __read_mostly = 25;
> +module_param(inflate_threshold_root, int, 0640);
> +
> +#define halve_threshold_root	(inflate_threshold_root / 2 + 1)
>  
>  static void __alias_free_mem(struct rcu_head *head)
>  {
> @@ -393,6 +400,8 @@ 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 +413,11 @@ 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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