On May 29, 2008, at 5:25 PM, Neil Horman wrote:
On Thu, May 29, 2008 at 11:06:11AM -0400, Vlad Yasevich wrote:
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.
That does sound odd, yes, a_rwnd should be reduced in response to
each received
frame. do you have tcpdumps of this test available?
Thanks
Neil
It looks like that you do not reduce the a_rwnd, because you discard
the message.
The problem seems to be that you ack it by incrementing the
cumtsn_ack...
Irene did the tests in the lab. We'll provide traces and a testprogram
tomorrow.
--
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*Neil Horman
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