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

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Message-ID: <4B702120.4090104@trash.net>
Date:	Mon, 08 Feb 2010 15:35:12 +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

Patrick McHardy wrote:
> 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.

This is what I'm going to commit unless someone spots any problems.
Resizing of non-init-namespaces is not supported, so its not necessary
to decide the questions you raised above at this time.



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