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From: amanda@intercon.uu.net (Amanda Walker)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: MacII FTP speeds on Ethernet
Message-ID: <1326@intercon.UUCP>
Date: 1 Aug 89 17:15:00 GMT
References: <9559@phoenix.Princeton.EDU> <8907250124.AA23044@multimax.encore.com> <3258@internal.Apple.COM>
Sender: news@intercon.UUCP
Reply-To: amanda@intercon.uu.net (Amanda Walker)
Organization: InterCon Systems Corporation
Lines: 28

In article <3258@internal.Apple.COM>, desnoyer@apple.com (Peter Desnoyers)
writes:
> My guess is that the bottleneck is in
> NCSA Telnet, or at least in its interface with MacTCP and the file system.

As I've already noted, I'd say it's mostly in the latter.  NCSA blocks disk
I/O in 8K blocks, which is pretty reasonable, but it still blocks.  The MacTCP
interface routines, while not the absolutely most efficient (in particular,
they use TCPRcv instead of TCPNoCopyRcv), aren not bad, and they certainly
don't account for the 80% difference in performance between your
memory-to-memory experiment and the observed FTP performance.  Using the
same MacTCP interface but not writing stuff to disk, I have no problem getting
100-150K bytes/second.

Another thing that can make for a big performance hit is running under
MultiFinder, since this reduces the percentage of time in which the FTP
server can process data and write it to the disk.

I'm glad that the file system will support asynchronous I/O in System 7.0;
that'll help this sort of thing a lot.

--
Amanda Walker
InterCon Systems Corporation
amanda@intercon.uu.net    |    ...!uunet!intercon!amanda
--
"We may have come here on different ships, but we're in the same boat now."
    --Betsy Rose