Re: ppp[oe?] dying under load

[Brian Somers <brian@Awfulhak.org>]

AFAIK, the problem is this:

When ppp(8) is given

  set speed sync
  set device "!pppoe ...."

it creates a SOCK_DGRAM socketpair() and connects one end to the 
invoked pppoe(8) process.  Ppp then select()s on it's end of the 
descriptor and send()s packets if select() says it's ok.

select() always says it's ok.  If ppp feeds pppoe packets faster 
than pppoe recv()s them (probably because it's busy trying to get rid 
of them), we run out of network buffers.

I don't know why pppoe dies though.

> Cool!!
> 
> Thanks for the feedback!!
> 
> I am using some of the logic from the ppp code ( in the area of the selects )
> to try to make the PPPoE daemon a bit smarter in it's handling...
> 
> I can see where there could be an issue of deadlock in the pppoe code, and
> maybe a smarter use of select will work towards resolving the problem..
> 
> I'll keep you both updated...
> 
> > 
> > On Wed, 20 Sep 2000, Bruce M. Walker wrote:
> > 
> > > Steve Williams <steve@genie96.com> and I have been exchanging notes
> > > and he is presently debugging usr.sbin/pppoe.  What Steve found is
> > > that pppoe itself exits on a bad writev call (ENOBUFS).  The common
> > > feature is that we both have slow (P90) CPUs.  The theory is that
> > > a faster CPU (or a slower link) may run this code OK.
> > 
> > I don't think it's related to processor speed: I'm using it with a 600 Mhz
> > Pentium III and I'm getting this problem as well.
> > 
> > -Ryan
> > 
> > --
> > Ryan McBride - mcbride@countersiege.com
> > Systems Security Consultant
> > Countersiege Systems Corporation - http://www.countersiege.com
> > 
> > 
> > 
> 
> 
> -- 
> 	Steve Williams, Calgary, Alberta, Canada
> 	Genie Computer Systems Inc.
> 	steve@genie96.com
> 
> "A man doesn't begin to attain wisdom until he recognizes that he is 
>  no longer indispensable."
> - Admiral Richard E. Byrd ( 1888-1957 )
> 
> 

-- 
Brian <brian@Awfulhak.org>                        <brian@[uk.]FreeBSD.org>
      <http://www.Awfulhak.org>                   <brian@[uk.]OpenBSD.org>
Don't _EVER_ lose your sense of humour !