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Date:      Mon, 08 May 2006 20:23:15 -0300
From:      tpeixoto@widesoft.com.br
To:        .@babolo.ru
Cc:        Lee Johnston <lee@wildcard.net.uk>, freebsd-net@freebsd.org, Julian Elischer <julian@elischer.org>, mihai@duras.ro
Subject:   Re: Packet loss with traffic shaper and routing
Message-ID:  <445FD2E3.8000900@widesoft.com.br>
In-Reply-To: <1146762831.921056.82828.nullmailer@cicuta.babolo.ru>
References:  <1146762831.921056.82828.nullmailer@cicuta.babolo.ru>

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I guess traffic stops if you have pipe rules.
In test 1, I did:

${fwcmd} pipe 1 config bw 512Kbit/s
${fwcmd} pipe 2 config bw 512Kbit/s
${fwcmd} add _allow_ all from any to any MAC any 00:11:22:33:44:55 in
${fwcmd} add _allow_ all from any to any MAC 00:11:22:33:44:55 any out

x 1600 times.
That caused lots of interrupts. Traffic was flowing although no shaping 
was done.
Then, in test 2, with the same rules above, I just flushed the pipes:
ipfw pipe flush
The traffic was there, and the result is what I said in last post...


"."@babolo.ru wrote:
> [ Charset ISO-8859-1 unsupported, converting... ]
>> Very good. You're right!
>> I inserted a rule to match all non-layer2 packets on the top of the 
>> ruleset and interrupts dropped 10~20% immediately.
>> Given that, I went to apply Julian's idea of grouping 'in' and 'out' 
>> pipe rules to reduce the searching on the firewall and that gave me a 
>> little bit more of performance.
>> As interrupts were still hitting 60% mark, I did some more experiences:
>>
>> Test 1: I changed all 'pipe' rules to 'allow' rules, so all packets were 
>> allowed and no shaping was done. The pipes were still there, but there 
>> were no rules pointing packets to them.
>> Result: No difference. Interrupts are the same as before.
>> Conclusion: It's not the shaping itself that slows the system.
>>
>> Test 2: With the same ruleset of test 1, I just removed all pipes (ipfw 
>> pipe flush).
> As far as I understand traffic stops after pipe flush,
> and this is reason for CPU goes down
> 
>> Result: Interrupts were only 20%!
>> Conclusion: Lots of pipes bother the system. I didn't figure out why, 
>> but it's not a coincidence. I tested several times to make sure.
>>
[...]



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