*BSD News Article 69656


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From: les@MCS.COM (Leslie Mikesell)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: FreeBSD vs. Linux
Date: 29 May 1996 00:12:51 -0500
Organization: /usr/lib/news/organi[sz]ation
Lines: 40
Message-ID: <4ogmcj$3f3@Mercury.mcs.com>
References: <318FA7CB.8D8@hkstar.com> <4o1om8$156@dyson.iquest.net> <4o4lel$mu3@Mars.mcs.com> <4o7gsh$8ge@dyson.iquest.net>
NNTP-Posting-Host: mercury.mcs.com

In article <4o7gsh$8ge@dyson.iquest.net>,
John S. Dyson <root@dyson.iquest.net> wrote:

>>But can you quantify that a bit?  I don't think my machines are
>>ever CPU bound to a point where I would notice this, but perhaps
>>it is just because I have cheap disks and network cards.
>>
>If your systems are not saturating your networks, then the slower networking
>perf on Linux won't make much difference. 

This helps, but doesn't completely make things clear.  I have 2
linux boxes and get 970-1100k/s ftp'ing large files between them
using the recent kernels.

>Slow network cards probably
>overshadow most of the os overhead of either FreeBSD, Linux or NetBSD.
>At 100% 10Mbps ethernet, an NE2000 takes 50% of your CPU for ISA
>bus overhead, and an SMC shared memory card takes about 25% of your
>CPU for ISA bus overhead. 

One machine has a 3c509b, the other an SMC ISA card.  I thought the
ISA bus supported about 5M/sec throughput - does this have an
impact on the PCI scsi controller running simultaneously?  Or memory
copies that don't involve the ISA bus?

>These numbers are constant if you are
>using a 486/66 or Pentium-Pro!!!  (since the bus timing is pretty much the
>same.)

Except that the Pentium should be able to get a lot more done in the
remaining 50%.  I'd expect the machine to be i/o bound most of the
time anyway.

>Things get more interesting (the OS becomes more critical) when you
>use efficient PCI based ethernet adapters or 100Mbps networks.

Or perhaps even multiple 10Mbs cards.

Les Mikesell
  les@mcs.com