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

From: Simon Horman <[email-masked]>
Date: Thu, 8 Dec 2011 09:40:09 +0900

On Wed, Dec 07, 2011 at 10:24:09AM -0500, Mike Maxim wrote:
> The reason I put that in is because the size of that table becomes
> more relevant/important if you decide to use the weights in the manner
> the patch lets you. It would be conceivable that someone might need to
> increase the size of that table to accommodate their configuration, so
> I thought it would be handy to be able to do that through the regular
> configuration system instead of editing the source.

Hi Mike,

I agree, but I think its also reasonable to consider IP_VS_SH_TAB_BITS as
a separate change.

Could you

1. Split the patch into a Kconfig patch and a ip_vs_sh.c patch
2. Remove spurious line additions from the resulting patches?

> 
> On Wed, Dec 7, 2011 at 6:30 AM, Pablo Neira Ayuso <[email-masked]> wrote:
> > On Wed, Dec 07, 2011 at 05:07:03PM +0900, Simon Horman wrote:
> >> From: Michael Maxim <[email-masked]>
> >>
> >> 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 <[email-masked]>
> >> Signed-off-by: Simon Horman <[email-masked]>
> >> ---
> >>  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!
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