[4046] in linux-net channel archive
Re: Question on performance
daemon@ATHENA.MIT.EDU (Alan Cox)
Fri Aug 16 09:27:42 1996
From: Alan Cox <alan@cymru.net>
To: dplatt@iq.tvsoft.com (Dave Platt)
Date: Fri, 16 Aug 1996 10:27:59 +0100 (BST)
Cc: chris@topdog.pas1.logicon.com, linux-net@vger.rutgers.edu
In-Reply-To: <199608160027.RAA00405@iq.TVSoft.com> from "Dave Platt" at Aug 15, 96 05:27:47 pm
> > Our Sun technical rep said that Suns can push data close to the ethernet
> > "wire speed" but PCs only get about 1/2 this rate. This advice was in the
The Sun rep is wrong. This is not unusual with Sun reps.
> (e.g. NCR53c810) and a busmaster Ethernet controller (e.g. PCNet-PCI
> or Tulip) will probably _not_ find its network or SCSI interfaces to
> be the bottleneck - the bottlenecks will be in the filesystem / block
> cache and in the network stack, I think
The bottleneck becomes memory speed and disk speed. On a 100baseT ethernet
you need to sustain about 10Mbytes/second from disk to memory and
10Mbytes/second from memory to network card, and do a checksum (in our
case a copy/checksum) between. Thats already 30Mbytes/second memory
bandwidth just to send the data out.
Alan
