Re: [Xen-users] trouble with TCP?

[Nivedita Singhvi <niv@xxxxxxxxxx>]

Kees Cook wrote:
> On Tue, Jun 21, 2005 at 03:28:16PM -0700, Nivedita Singhvi wrote:
>
> > Looks like you need to add a default route on domU.
> >
> > Could you fix that and try again?
>
> Sure, added, but no change in behavior.  (And shouldn't: the packets get 
> to and are responded to by the host, but when the client gets the 
> SYN,ACK it just ignores it.)
The next issue is that your tcp_mem seems to be
on the disfunctionally low.  Your netstat -s output seems
truncated on domU (only had the first 2 Linux MIB counters).
You might have otherwise been able to confirm whether you
could even open a socket or were hitting memory pressure.

Mainline used to disallow tcp allocations if total usage
in the system was at sysctl.tcp_mem[2], and entered memory
pressure at sysctl.tcp_mem[1].

net.ipv4.tcp_mem = 3072 4096    6144

How did this get so low? Bump that up by a factor of 100
each (assuming your domain has enough memory allocated, forgot
to ask).

Admittedly, that was older mainline behaviour, might have
changed recently (post 2.6.11) and not sure exactly what 2.0.6 is
running.
this wee
> This is running the stable binrary release of the Xen website, if that 
> helps.  I noticed the xenU doesn't have any kernel network modules 
> built.  Is it possible something is misconfigured in the build?  Are 
> other people able to do TCP between host/client in a routed config 
> running the 2.0.6 stable release?
It used to work fine on unstable about 2 months back. Haven't tested
the testing tree myself, unfortunately.

thanks,
Nivedita

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