Re: [Xen-users] trouble with TCP?

[Kees Cook <kees@xxxxxxxxxxx>]

On Tue, Jun 21, 2005 at 04:37:04PM -0700, Nivedita Singhvi wrote:
> The next issue is that your tcp_mem seems to be
> on the disfunctionally low. 

Hm.  It's the same on xenU and xen0 (but way lower than another machine 
I looked at).  Both xenU and xen0 have 96M allocated for main memory.  
(And, xen0 has no problems with TCP connections to other hosts.)

> 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.

Hm, that is interesting.  It's actually not truncated; that's how it 
looks.  If I do a "telnet localhost 22" (which connects fine) the 
"TcpExt" section changes to:

TcpExt:
    1 packets directly queued to recvmsg prequeue.
    1 of bytes directly received from prequeue
    1 packet headers predicted
    2 acknowledgments not containing data received
    3 predicted acknowledgments
    0 TCP data loss events

> 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).

I bumped it; no luck.

> It used to work fine on unstable about 2 months back. Haven't tested
> the testing tree myself, unfortunately.

How strange.  I guess I need to build my very own to see if recent stuff 
fixes it.  Pretty strange.  Thanks for looking at this.  I'm quite 
baffled.

-- 
Kees Cook                                            @outflux.net

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