Re: [PATCH] IPVS: Modify the SH scheduler to use weights

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Wed, Dec 07, 2011 at 05:07:03PM +0900, Simon Horman wrote:
> From: Michael Maxim <mike@okcupid.com>
> 
> Modify the algorithm to build the source hashing hash table to add
> extra slots for destinations with higher weight. This has the effect
> of allowing an IPVS SH user to give more connections to hosts that
> have been configured to have a higher weight.
> 
> Signed-off-by: Michael Maxim <mike@okcupid.com>
> Signed-off-by: Simon Horman <horms@verge.net.au>
> ---
>  net/netfilter/ipvs/Kconfig    |   15 +++++++++++++++
>  net/netfilter/ipvs/ip_vs_sh.c |   20 ++++++++++++++++++--
>  2 files changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/Kconfig b/net/netfilter/ipvs/Kconfig
> index 70bd1d0..af4c0b8 100644
> --- a/net/netfilter/ipvs/Kconfig
> +++ b/net/netfilter/ipvs/Kconfig
> @@ -232,6 +232,21 @@ config	IP_VS_NQ
>  	  If you want to compile it in kernel, say Y. To compile it as a
>  	  module, choose M here. If unsure, say N.
>  
> +comment 'IPVS SH scheduler'
> +
> +config IP_VS_SH_TAB_BITS
> +	int "IPVS source hashing table size (the Nth power of 2)"
> +	range 4 20
> +	default 8
> +	---help---
> +	  The source hashing scheduler maps source IPs to destinations
> +	  stored in a hash table. This table is tiled by each destination
> +	  until all slots in the table are filled. When using weights to
> +	  allow destinations to receive more connections, the table is
> +	  tiled an amount proportional to the weights specified. The table
> +	  needs to be large enough to effectively fit all the destinations
> +	  multiplied by their respective weights.

Hm, does this really belong to this patch?

> +
>  comment 'IPVS application helper'
>  
>  config	IP_VS_FTP
> diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c
> index 33815f4..e0ca520 100644
> --- a/net/netfilter/ipvs/ip_vs_sh.c
> +++ b/net/netfilter/ipvs/ip_vs_sh.c
> @@ -30,6 +30,11 @@
>   * server is dead or overloaded, the load balancer can bypass the cache
>   * server and send requests to the original server directly.
>   *
> + * The weight destination attribute can be used to control the
> + * distribution of connections to the destinations in servernode. The
> + * greater the weight, the more connections the destination
> + * will receive.
> + *
>   */
>  
>  #define KMSG_COMPONENT "IPVS"
> @@ -99,9 +104,11 @@ ip_vs_sh_assign(struct ip_vs_sh_bucket *tbl, struct ip_vs_service *svc)
>  	struct ip_vs_sh_bucket *b;
>  	struct list_head *p;
>  	struct ip_vs_dest *dest;
> +	int d_count;
>  
>  	b = tbl;
>  	p = &svc->destinations;
> +	d_count = 0;
>  	for (i=0; i<IP_VS_SH_TAB_SIZE; i++) {
>  		if (list_empty(p)) {
>  			b->dest = NULL;
> @@ -113,14 +120,23 @@ ip_vs_sh_assign(struct ip_vs_sh_bucket *tbl, struct ip_vs_service *svc)
>  			atomic_inc(&dest->refcnt);
>  			b->dest = dest;
>  
> -			p = p->next;
> +			IP_VS_DBG_BUF(6, "assigned i: %d dest: %s weight: %d\n",
> +				      i, IP_VS_DBG_ADDR(svc->af, &dest->addr),
> +				      atomic_read(&dest->weight));
> +
> +			/* Don't move to next dest until filling weight */
> +			if (++d_count >= atomic_read(&dest->weight)) {
> +				p = p->next;
> +				d_count = 0;
> +			}
> +
>  		}
>  		b++;
>  	}
> +
>  	return 0;
>  }
>  
> -

While at it, would you remove this unnecessary deletions/additions.

Thanks!