[Users] Problem with TCP window too large for TCPRCVBUF still present

[Vitaliy Gusev]

On 25 March 2008 15:50:46 Marcin Owsiany wrote:
> On Tue, Mar 25, 2008 at 03:33:08PM +0300, Vitaliy Gusev wrote:
> > Does the original kernel 028.53.3 still have issue with sending ack?
> 
> I didn't try.
> 
> > I see if VE has too small tcprcvbuf (about 30000) then server retransmit
> > packets to VE. But i can't reproduce a deadlock state.
> 
> Maybe you need a crappy internet connection to be able to reproduce this
> :)
> 
> The way I did that recently was:
>  1) saturate the link (medium-quality 4 Mb ADSL) in both directions from
>  another machine

Traffic from other machine to VE (and vise-versa) or from other machine to VE0?

Is it TCP or ICMP traffic?


> 
>  2) give it a couple of minutes until the transfer rates are steady
> 
>  3) start downloading a large file in a VE (I'm in UK and used a
>  debian-cd mirror in Australia for that)
> 
>  4) give it a couple of minutes until the transfer rate is steady (you
>  can observe the current window size in tcpdump - just wait until it
>  stops changing)
> 
>  5) then stop both transfers on the other machine
> 
>  6) after some time (10-20 seconds), the testing VE will notice that
>  more bandwidth has become available, and you will notice that the
>  window size will start increasing, to increase the transfer rate
> 
>  7) for me, at the point the window size has reached about 9KB (it takes
>  just a couple of seconds from the moment the window started
>  increasing), the deadlock occured
> 



-- 
Thank,
Vitaliy Gusev