Path: utzoo!attcan!uunet!jarthur!elroy.jpl.nasa.gov!ames!pasteur!ucbvax!vax.ftp.com!jbvb
From: jbvb@vax.ftp.com (James Van Bokkelen)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Re: DOS/ftp/multi-process
Message-ID: <9002271421.AA23443@vax.ftp.com>
Date: 27 Feb 90 14:21:39 GMT
References: <30620@brunix.UUCP>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 16

DESQview won't help "keep the clients in synch", because it does its multi-
tasking via time-slicing.  If you try to use multiple processes, it will only
run P1 for a while, then switch to P2, etc.  Meanwhile, it may switch out of
a context in which the TCP kernel is active, which will leave it blocked
(NET_ERR_REENTRY) until that context is run again.

I'd recommend starting the kernel with as many packet buffers as the number
of open TCP connections allows, and looking carefully at the mapping of
write length to the Sun TCP MSS value.  If the Suns ask for an MSS of 1024
bytes, your writes should be some multiple of that, as should your receive
window (use setsockopt() in the Unix application).  If you really want them
to all be as close to synchronized as possible, only write 1024 bytes to
each connection at a time.

James B. VanBokkelen		26 Princess St., Wakefield, MA  01880
FTP Software Inc.		voice: (617) 246-0900  fax: (617) 246-0901