Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!ames!elroy!cit-vax!mangler
From: mangler@cit-vax.Caltech.Edu (Don Speck)
Newsgroups: comp.unix.wizards
Subject: Re: rdump, Ethernet slowness
Summary: tcp throughput should be higher
Message-ID: <4835@cit-vax.Caltech.Edu>
Date: 10 Dec 87 08:47:04 GMT
References: <788@hsi.UUCP> <1268@laidbak.UUCP>
Organization: California Institute of Technology
Lines: 19

In article <1268@laidbak.UUCP>, mdb@laidbak.UUCP (Mark Brukhartz) writes:
> I believe that the /etc/rmt protocol, used by rdump, is synchronous.	Each
> I/O operation is acknowledged (back through the Ethernet) before the next
> one is begun.

That wasn't the bottleneck.  The problem lies in this section:

In article <788@hsi.UUCP>, stevens@hsi.UUCP (Richard Stevens) writes:
>	 52,000 bytes/sec - speed of a C program writing 1000 32768-byte
>			    buffers to another process on the other system,
>			    across the Ethernet, using a stream socket, as
>			    in the 552,000 bytes/sec example given above.

52Kbytes/sec of tcp throughput is ATROCIOUS for a VAX/785 with a good
Ethernet board like an Interlan NI1010A.  My 750's, with the same kind
of Ethernet board, do 88 Kbytes/sec with reads of that size.  I cannot
account for why his throughput would be this poor.  Any ideas?

Don Speck   speck@vlsi.caltech.edu  {amdahl,scgvaxd}!cit-vax!speck