netdev - Re: [PATCH for 2.6.33] conntrack: restrict runtime hashsize modifications

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Date:	Mon, 08 Feb 2010 14:34:05 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Alexey Dobriyan <adobriyan@...il.com>
CC:	davem@...emloft.net, jonathan@...masters.org,
	eric.dumazet@...il.com, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH for 2.6.33] conntrack: restrict runtime hashsize modifications

Alexey Dobriyan wrote:
> On Fri, Feb 05, 2010 at 11:00:03AM +0100, Patrick McHardy wrote:
>> Actually it doesn't seem like much more work to allow changing
>> table size, the main problem is that sysfs module parameters
>> don't seem to fit into the network namespace model at all.
> 
> Well, they "fit" as they're global because modules are global.
> So we can make every netns hashtable size equals to module param,
> or make it bounded by module param
> or make initial hashtable size and not bounded
> or million other things.

Feel free to suggest your preferred method.

>> Please be more specific about your suspected slowdowns.
> 
> I meant net->ct.htable_size in hash functions _if_ you're not allowing
> changing it from inside netns.
> 
>> What's "everything"? What's different about the hashsize
>> compared to the many members we already moved to per-netns
>> structs?
> 
> But whatever. I think per-netns hashtable size shouldn't be done
> that late.

This is a regression. You can not simply disable resizing and call
it a bugfix.

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