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Date:      Fri, 18 Jan 2013 13:10:17 -0800
From:      Richard Sharpe <realrichardsharpe@gmail.com>
To:        freebsd-questions@freebsd.org
Subject:   Have there been any fixes for long TCP delays with FreeBSD 8.3 or 9.x?
Message-ID:  <CACyXjPy3ADXHJ=YH%2BzC4NuzKb778U9GAUHEy-K90dCMq_qKEYA@mail.gmail.com>

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Hi folks,

I am seeing a problem when copying large files via SMB/Samba from a
FreeBSD 8.0-based system (with Samba 3.6.6 and ZFS etc) where
eventually Windows drops the connection.

However, it seems, based on three captures I have, that what has
happened is that FreeBSD has not supplied any data on the connection
for 50-60 seconds and the Windows 60-second timeout trips.

In each case, what I see is a large number of 1500-byte frames go out.
Then Windows ACKs a reasonable amount of data, 30+K or so, and then
sends another ACK to ack everything so far received.

Then in two cases, after about 52 seconds I see some more data in two
of the captures I have but after a further few seconds, Windows
disconnects. In the last capture, there was no further data for 60
seconds, so Windows disconnected.

I know there should have been more data because:

1. The READ requests are for 64kiB and there is still data to come and
the sequence numbers match up.

2. In my Samba traces I know that Samba has gone on to process the
next SMB2 command in sequence and the time difference between these
are of the order of 1mS and Samba in this case is operating in sync
mode where it does not read the next command off the socket until it
has finished writing the response for the previous command to the
socket.

The system is relatively idle. Only one smbd and some web traffic
(inbound as a result of a get).

I am hoping that this describes a known problem. I can provide
captures on request. They will have to be cut-down as they are 300 to
500MB in length.

--=20
Regards,
Richard Sharpe
(=A6=F3=A5H=B8=D1=BC~=A1H=B0=DF=A6=B3=A7=F9=B1d=A1C--=B1=E4=BE=DE)



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