Re: [lvs-users] Increase the default connection hash table value

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Increase the default connection hash table value
From: hirantha <hirantha@xxxxxxxxxxxxxxx>
Date: Fri, 06 Jun 2008 22:34:26 +0530
Thanks Graeme, As you said, better I check the default configurations in action 
for sometimes.


Graeme Fowler wrote:
> Hi
> On Thu, 2008-06-05 at 17:53 +0530, hirantha wrote:
>> So now I know the requirement. I expect 300 connections per second and each 
>> connection keep for 200 
>> seconds. So my value on the connection hash table should be 16 (2^16=65536)
> No. After 200 seconds you will have (300 * 200) = 60000 connections in
> the table. This does not mean you need the hash table to be 16 bits!
> You'll find long discussions about sizing the hash table in the HOWTO,
> but it can be summed up roughly as follows:
> The size of the table is the number of *rows* in the table. The rows
> have an unlimited (theoretically) number of columns available. The
> larger the number of rows, the slower the lookup.
> This means lookup performance can be increased by increasing the number
> of rows available in the hash, but the tradeoff is that it then takes up
> more memory when idle. With the speed of today's processors I'd suggest
> that you try working with the default 2^12, 4096 and see what happens.
> To answer your other question, you need to recompile the kernel
> (actually just the ip_vs module) to make a change to the hash table
> size, and then unload and reload the module to apply it. For most people
> this necessitates a complete kernel recompile followed by a reboot but
> there are more graceful ways to achieve it!
> Graeme
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