GigE & IDE throughput!
From: Coenraad Loubser (c10u_at_ananzi.co.za)
Date: Tue, 19 Apr 2005 23:30:55 +0200
> Chuck Forsberg wrote:
>>I have XP on a 2.4 P4 talking to Fedora Core 3 on a 2.0 Celeron
>>connected by 100 MHz Ethernet. XP accesses Samba shares on
> Do you know your current throughput with 100Mbps? How close does it
> crowd your hard disk throughput? At clients? At server? Where's the
Well, lets see. IDE throughput is effectively 20MiB-60MiB/s. Thats
~160mbits to 480mbits. So I suppose that means that you can boot a PC
over the lan just as fast as from a fixed disc?
Hmm, so what about a pc with 2-3-4GB of ram, a ramdisk, with the lan
bootable OS, such as XP or Linux.
The bottleneck for booting up a PC is the disk speed. Mostly.
So you should be able to boot XP, I would guess, half the time, if you
boot from a ramdisk over gigabit ethernet!
Well--- that is if the speed is closer to 800mbits!
Anyone got any actual throughput measurements?
Two way to increase performance
Increase the minimum packet length
Decrease the distance span
Multiple transmissions arriving simultaneously results in all packets
being lost for a typical hub
Ouch, this particular test peaked 160Mbits.
Ooh, another test - FreeBSD makes linux look like windows when it comes
to lan performance and throughput at gigabit levels! Wow!
Shit people, I cant find any gigabit bandwidth measurements exceeding
160Mbps! Do I have to test EVERYTHING myself? Will do a measurement and
post it here..
Well Well. http://sd.wareonearth.com/~phil/jumbo.html says you should
use "Jumbo frames" (9000 bytes instead of 1500!) This halves your cpu
usage and adds 30% to your thoughput. Dont think its compatible with
slower networks though, but its not a bad trade! You cant go bigger than
12000 bytes packets because of the CRC field. (Haha, IPv6 has got a 4GB
packet size limit! Geeez!)
>>How much faster would Gigabit Ethernet?
> See above and realize that _many_ people are "satisfied" with only
> 300-400Mbps on the wire. Will that exceed your disk throughput? Solve
> your problems?
>>Does Linux support the cheap gigabit ethernet boards?
> Depends on the chipset(s) used on the nic(s). Can also depend on any
> switches/routers along the pathway. Cheaper cards stress the OS/cpu
> more than "server" grade cards which offer more on card
> GigE generates _lots_ of hardware interrupts and can really stress a
> machine if not properly set up. "Tweaking" the setup so it _is_ proper
> is more work than many people are willing to persue. Don't expect
> miracles or a painless upgrade path. This is why so many folks settle
> for ~350Mbps.
GigE being Gigabit Ethernet obviously!
> What hardware do you currently have on hand? Willing to replace any of
> it? Use Goolge to see how Linux supports your current hardware in a
> GigE network. What do you expect GigE to provide that your current
> setup does not? More speed? Greater reliability? Easier setup?
> Easier troubleshooting?
> If you already have all the pieces, just try it out and see what you
> If you are thinking of buying new toys, I usually tell people not to
> bother unless they have a bandwidth problem that they think GigE will
> If you're willing to experiment and want to learn, go ahead ;)
> good luck,