Re: receiver window questions

[Vlad Yasevich <vladislav.yasevich@hp.com>]

Hi Michael

Michael Tuexen wrote:
> Hi Vlad,
> 
> we are currently testing the receive behaviour of Linux (and
> other systems).
> 
> We are using Fedora 9, kernel 2.6.25-14.
> 
> The receiver application just opens a 1-to-many style socket
> and sleeps forever, not reading any messages.
> 
> The sender (on a different machine), sends a lot of messages of the
> same size, all on stream 0, ordered.
> 
> When setting the receive buffer space (using the SO_RCVBUF socket option)
> to 10000 we oberserve the following:
> 
> - When sending messages of size 1000 bytes, the receiver SACK the first,
>   announces 9000 bytes windows, SACKs the second announces 8000 bytes
>   and so on. Look fine. The a_rwnd goes down to 0 and discards messages.
>   Everything is fine.
> 
> - When sending messages of size 100 bytes, the receiver SACKs the first
>   messages and reduces the a_rwnd accordingly. Then it looks like the
>   receive buffer grows, because messages are accepted and the a_rwnd does
>   not shrink. Is this intended?

No.  The a_rwnd should go down to 0 as before.

>   We also figured out that after about 670947 messages of size 100 bytes
>   the association is aborted. Is this intended?

This is also not intended.  We'll take a look.

Thanks
-vlad

> 
> - Sending messages of size 10 bytes is similar to 100 byes.
> 
> Best regards
> Michael
> 
>