ipfw rules consuming CPU

[Michael Spratt]

I have Linux & FreeBSD systems running ipfw with 80 rules with 70Mb/s 
symmetric, passing traffic for about 1000-1200 hosts.

Alexander V. Chernikov wrote:
> On 09.06.2012 01:56, Sami Halabi wrote:
>> Hi,
>>
>> I Manage a FreeBSD server as an edge router&  firewall.
>> the setup has 10G interfaces (ixgbe-82599EB) and 1G 
>> interfaces(em-82571EB&
>> bce-BCM5709) connected to 10G/1G switches.
>>
>> With the following setup i get higher cpu usage:
>> bce1-upstream provider with little bandwidth, so i use pipes to limit
>> users, and subnets
>> ix0 - Internet Exchange
>>
>> some rules.
>> .
>> .
>> .from 4000 starts pipes for specefic ips bandwidth allocations
>> 04000    6210053001    5845967300616 pipe 1003 ip from 182.46.92.13 
>> to any
>> out xmit bce1
>> 04100   41289897537    3064110648124 pipe 1004 ip from any to 
>> 182.46.92.13
>> in recv bce1
> You should use pipe tablearg for that. Traversing 4k rules effectively 
> kills all performance.
>
>> .
>> .
>> .
>> .7000 is the wider pipeline for the whole block
>> 07000    9127154724    4651308720315 pipe 1000 ip from  
>> 182.46.92.0/24 to
>> any out xmit bce1
>> 07100    4837016828     458027989917 pipe 1002 ip from any to
>> 182.46.92.0/24 in recv bce1
>> last rule default to accept...
>>
>> specefic pipes (1003-...) have limits say between 1-10Mbps, and the 
>> wider
>> pipe (1000 and 1002) has a global limit of 40MBps that should be 
>> reached by
>> all other non-specefic ips, config like this:
>> #Wide
>> ipfw pipe 1000 config bw 40Mbit/s queue 200Kbytes
>> ipfw pipe 1002 config bw 40Mbit/s queue 200Kbytes
>> #specefic
>> ipfw pipe 1003 config bw 9Mbit/s queue 200Kbytes
>> ipfw pipe 1004 config bw 9Mbit/s queue 200Kbytes
>> ipfw pipe 1005 config bw 3Mbit/s queue 200Kbytes
>> ipfw pipe 1006 config bw 3Mbit/s queue 200Kbytes
>> ipfw pipe 1007 config bw 5Mbit/s queue 200Kbytes
>> ipfw pipe 1008 config bw 5Mbit/s queue 200Kbytes
>> ipfw pipe 1009 config bw 10Mbit/s queue 200Kbytes
>> ipfw pipe 1010 config bw 10Mbit/s queue 200Kbytes
>>
>>
>> with this configuration when i have lots of traffic (3-6GB) going via 
>> ix0
>> (not necessarly the ips described above, lets say to a server in my 
>> net ip
>> 1832.46.93.4 and users behind the Internet Exchange) i see high cpu 
>> usage
>> (70-90%).
>>
>> my first test was to: ipfw add 1 allow all from any to any, and cpu 
>> usage
>> drops immediatly to 10-15%.
>> but that not why i want (i wantto keep thelimits) so I add rule right
>> before 4000 and the cpu usage drops down to 10-20%:
>> 03020 1669463072808 1493341413029803 allow ip from any to any via ix0
>>
>>
>> Any advice why this happens? or should it be there in the first place?
>> I use FreeBSD 8.1-R-p10-amd64.
>>
>> Thanks in advance,
>>
>
>