RE: pf ALTQ bandwidth limited to a 32bit value (4294Mb)

2011-07-06 Thread Greg Hennessy 
> 
> ALTQ using hfsc is limited to a maximum parent bandwidth of 4294Mb.
> This value is 2^32 or 4,294,967,296 bits. If you set the bandwidth any higher,
> altq will flip back to zero. This "bug" was found when trying to test 10 
> gigabit
> and 40 gigabit bandwidth models. 

What a problem to have :-) 

On a side note out of pure curiousity, what's PF performance like up in the 
stratosphere under those sort of loads/packet rates ? :-)


Greg

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Re: pf ALTQ bandwidth limited to a 32bit value (4294Mb)

2011-07-06 Thread Peter N. M. Hansteen 
Calomel Org  writes:

> ALTQ using hfsc is limited to a maximum parent bandwidth of 4294Mb.
> This value is 2^32 or 4,294,967,296 bits. If you set the bandwidth any
> higher, altq will flip back to zero. This "bug" was found when trying
> to test 10 gigabit and 40 gigabit bandwidth models. These tests were
> done on OpenBSD 32bit and 64bit as well as FreeBSD 32bit and 64bit.

Nice to hear you've got access to relatively high end gear for testing,
I'm sure it will come in handy when the time comes to test any proposed
fixes.

The obvious workaround in the short term is to do the traffic shaping
and filtering a bit closer to the end user, where bandwidth is a bit
more scarce.  In the slightly longer term, I'm sure a verified bug
report (with patches against -current code if feasible) would be much
appreciated.

- Peter

-- 
Peter N. M. Hansteen, member of the first RFC 1149 implementation team
http://bsdly.blogspot.com/ http://www.bsdly.net/ http://www.nuug.no/
"Remember to set the evil bit on all malicious network traffic"
delilah spamd[29949]: 85.152.224.147: disconnected after 42673 seconds.
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pf ALTQ bandwidth limited to a 32bit value (4294Mb)

2011-07-06 Thread Calomel Org 
ALTQ using hfsc is limited to a maximum parent bandwidth of 4294Mb.
This value is 2^32 or 4,294,967,296 bits. If you set the bandwidth any
higher, altq will flip back to zero. This "bug" was found when trying
to test 10 gigabit and 40 gigabit bandwidth models. These tests were
done on OpenBSD 32bit and 64bit as well as FreeBSD 32bit and 64bit.

If anyone else can verify this independently and agree with the
results I would be happy to register it as a bug. 


How to replicate:

A quick test is setting the bandwidth to 4294Mb and doing a pfctl -sq
to check altq. 

 altq on $ExtIf bandwidth 4294Mb hfsc queue { ack, web}
 queue root_em0 on em0 bandwidth 4.29Gb priority 0 {ack, web}

Now set the bandwidth to 4295Mb and notice altq has flip to zero and
add the 32.70Kb difference.

 altq on $ExtIf bandwidth 4295Mb hfsc queue { ack, web }
 queue root_em0 on em0 bandwidth 32.70Kb priority 0 {ack, web}

Again, we can set the bandwidth to a multiple of two(2) to 8589Mb.
The bandwidth value flips to zero once and the result is 4.29Gb.

 altq on $ExtIf bandwidth 8589Mb hfsc queue { ack, web}
 queue root_em0 on em0 bandwidth 4.29Gb priority 0 {ack, web}

If we add one more megabit to 8590Mb the value flips twice and we are
left with 65.41Kb.

 altq on $ExtIf bandwidth 8590Mb hfsc queue { ack, web}
 queue root_em0 on em0 bandwidth 65.41Kb priority 0 {ack, web}


Thanks.

--
   Calomel @ https://calomel.org
   Open Source Research and Reference
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