userland pppoe unusable/slow/dropping packets

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userland pppoe unusable/slow/dropping packets

Adam-29
Trying to use userland pppoe for a DSL connection, I connect fine, and I  
can pass small amounts of traffic through the link without issues.  But as  
soon as I send real traffic through it (a couple hundred Kb/sec of pretty  
ordinary DNS and HTTP traffic) latency shoots up to 1500ms and it starts  
dropping packets really badly, like 50% or so.  Pinging from the openbsd  
machine gives lots of:

sendto: No buffer space available

The CPU is 90-95% idle.  Using kernel pppoe I can ping flood the default  
gateway with 1400 byte packets while sending that same traffic through and  
everything is fine, so it isn't the modem/ISP/etc.  I know userland pppoe  
is obviously going to be slower, but is it supposed to be this bad?  I  
can't use kernel pppoe as it appears to be causing the machine to lock up  
occasionally and require a hard reset.


$ cat /etc/hostname.tun0
rdomain 2 group egress description bell
!/usr/sbin/ppp -ddial -unit0 bell

$ cat /etc/ppp/ppp.conf
default:
         set log Phase Chat LCP IPCP CCP tun command

bell:
         set device "!/usr/sbin/pppoe -i em2"
         set mtu max 1492
         set mru max 1492
         set speed sync
         disable acfcomp protocomp
         deny acfcomp
         enable lqr
         accept lqr
         enable mssfixup
         set authname "XXXX"
         set authkey "XXXX"

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Re: userland pppoe unusable/slow/dropping packets

Stuart Henderson
On 2013-04-12, Adam <[hidden email]> wrote:

> Trying to use userland pppoe for a DSL connection, I connect fine, and I  
> can pass small amounts of traffic through the link without issues.  But as  
> soon as I send real traffic through it (a couple hundred Kb/sec of pretty  
> ordinary DNS and HTTP traffic) latency shoots up to 1500ms and it starts  
> dropping packets really badly, like 50% or so.  Pinging from the openbsd  
> machine gives lots of:
>
> sendto: No buffer space available
>
> The CPU is 90-95% idle.  Using kernel pppoe I can ping flood the default  
> gateway with 1400 byte packets while sending that same traffic through and  
> everything is fine, so it isn't the modem/ISP/etc.  I know userland pppoe  
> is obviously going to be slower, but is it supposed to be this bad?

http://marc.info/?l=openbsd-tech&m=130134805219592&w=2 might help.

> I can't use kernel pppoe as it appears to be causing the machine to lock up  
> occasionally and require a hard reset.

This is a rubbish bug report, see http://www.openbsd.org/report.html