Re: Ldirectord Feature Request

To: Joseph Mack NA3T <jmack@xxxxxxxx>
Subject: Re: Ldirectord Feature Request
Cc: Caleb Anthony <caleb.anthony@xxxxxxxxx>, lvs-devel@xxxxxxxxxxxxxxx
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Tue, 5 May 2009 22:45:22 +1000
Hi Joe,

On Sat, May 02, 2009 at 05:33:43AM -0700, Joseph Mack NA3T wrote:
> On Sat, 2 May 2009, Simon Horman wrote:
>> I'll double check, but I think the weight specifies a proportion
>> of conections rather than an absolute number. Could you let
>> me know which documentation you are looking at?
> it's the number of connections
> see section 4.10.2 of

That may have been the case in the past, but examining the code now
I don't see any evidence of weight = number of connections for the purpose
of calculating overload.

As far as I can see a real-server is only regarded as
being overloaded if the IP_VS_DEST_F_OVERLOAD flag is set.
And that flag only seems to be set in ip_vs_bind_dest()
where the criteria is that u-threshhold - as supplied
by ipvsadm - has been exceeded.

Specifically, I am looking at ip_vs_sh_schedule(), ip_vs_sh_get()
and is_overloaded() in net/netfilter/ipvs/ip_vs_sh.c in 2.6.30-rc4.

Caleb, are you observing that weight = number of connections?
If so, which kernel are you running?

> no-one used the -SH scheduler for years because no-one understood how to 
> use it. I expect that weighting by the number of connections was probably 
> the easiest to code up, but it's not particularly useful

I agree with your comments regarding utility.
If it is the case then I think it should be changed.

Simon Horman
  VA Linux Systems Japan K.K. Satellite Lab in Sydney, Australia
  H:            W:

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