Date: Fri, 22 Jan 2010 14:52:34 -0800 From: Julian Elischer <julian@elischer.org> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: freebsd-net@freebsd.org, ??????? <ekamyshev@omsk.multinex.ru> Subject: Re: Netgraph performance with ng_ipfw Message-ID: <4B5A2C32.7050802@elischer.org> In-Reply-To: <20100122224156.GB27338@onelab2.iet.unipi.it> References: <C6F35B81AA3747D1B11CAC169F2D8D84@evgen> <20100122224156.GB27338@onelab2.iet.unipi.it>
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Luigi Rizzo wrote:
> On Sat, Jan 23, 2010 at 03:32:11AM +0600, ??????? wrote:
>> Hi,
>> I have several routers under heavy load, running FreeBSD 7.2
>> These routers use Netgraph to impelement traffic shaping and accouting
>> (using ng_car and ng_netflow nodes).
>> Packets are passed from firewall to netgraph using the following rules
>> accounting:
>> netgraph 100 ip from any to any in
>> shaping:
>> netgraph tablearg ip from any to table(118) out
>> netgraph tablearg ip from table(118) to any in
>>
>> Table 118 contains users' ip addresses with tablearg referencing configured individual ng_car node.
>> At peak, there are 1500-2000 entries in table and configured nodes.
>> The problem is that at peak load the router loses packets. After studying the sources & doing some debugging,
>> it became clear that packets are being droped at netgraph queue, at ng_alloc_item function:
> ...
>> When the large number of hooks is present, as in the configuration given in the beginning of this message,
>> this would cause an obvious decrease in performance - for each packet passed from ipfw to netgraph,
>> 1 to 1500-2000 iterations are needed to find matching hook. And again, it seem to be a trivial task to rewrite
>> this code to find hook by hash or even by array.
Each node type has the ability to supply a "hook lookup method"
if (node->nd_type->findhook != NULL)
return (*node->nd_type->findhook)(node, name);
I added this so that if a hook had thousands of hooks it could supply
a smart method to look them up in a way that is relevant to that node
type.
I have never used the netgraph ipfw node so I don't know how it works
or if this is at all relevant.
>
> i solved exactly this problem in my recent ipfw rewrite (in HEAD), but it
> is not terribly trivial, though, because you should consider memory
> costs (the cookie space is large) and the need to handle reconfigurations
> without blocking the forwarding for a long time.
>
> You can use the same techniques (and possibly code) i used in ipfw,
> but i suspect it will take a good 1-2 weeks of work to have a production
> quality thing (I am not familiar with netgraph code and configuration
> tools so i may underestimate the work).
>
> cheers
> luigi
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