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Mixing Gigabit, Copper, and Linux
iampgray writes: "With copper-based gigabit cards selling for less than $36 these days, what kind of performance can you expect -- especially in the often-overlooked Linux market? We sought out to test exactly what you could expect from copper-based gigabit solutoins for the desktop interface through the cluster-targeted products. Name brands and off-brands were put through the wringer. How'd they fare? Interesting results to say the least."
Just fyi, Macintosh 1000BaseT ethernet controllers go directly to the memory controller, bypassing PCI altogether..
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Well, check out the docs first off. It's hard to get much out of GBit, since most of the utilities don't call the socket open with properly sized buffers/window/whatever.
/* 8192 */
I set up optical gigabit for some NAS type things at work, and out of the box, GBit performed maybe 30% better than 100 Mbit. We are talking about 110Mbit peaks, compared to 80Mbit peaks with 100Mbit switched.
Setting the MTU to 6144 (max that I could set it to with the ns83820.o) I started to get peaks around 300Mbit/sec.
I tried recompiling the module for higher limits, since in the source it has:
#define RX_BUF_SIZE 6144
But if I put in 8192, or 9000 like I wanted it to be, it would crask or lock up.
Anyway, it's not trivial to get good performance out of GBit, and definitely don't expect anywhere near 10X gain.
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Well... copper is cheaper than fiber for the moment. I'd hate to think what my 50 meter run from my router to the second floor of my townhouse would cost if it was fiber.
I use optical runs for my audo as well, but those are all under a meter, for the most part, and around $30 or so a piece. Not too much money for the purpose, but I dont' think I'd enjoy paying for a 50 meter run. Never mind the cost of devices with optical interfaces.
That said, I guess the only reason I'd consider GB copper is that it's no more expensive than 100 base-T...
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apparently Pricewatch.com has D-Link 8-port 10/100/1000baseT auto-detect switches listed for under $150!
;).
These are for 8x100-base-T with a gigabit uplink. I researched this a while ago, when speccing out my dream network
The cheapest full-gigabit switch D-link sells is about $1500.
The cards are well priced for home use, and CAT5E cabling is cheap too. The problem with gigabit ethernet is not the cards, it is the lack of switches or even plain hubs at an affordable price point. There are lots of switches out there with a single gigabit port, but even those are a couple of hundred dollars. If you want multiple gigabit ports, you are looking at more than $600 for the bottom rung products.
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Someone needs to learn the difference between a gigabit and a gigabyte....
Doing Math we can calculate that a full gigabit of transfer is 125 Megabytes a second. I think this is possible with high end hard drive technologies like SCSI RAID and speeds like this will probably show up in the desktop in a few years.
And, of course, not all data has to be written on Hard Drives. You could have a router or switch that will pass along a gigabit of packets a seconds but it certainly doesn't write them to the hard drive. You could for example but in a Gigabit Ethernet connection between two nearby buildings.
Tim
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I got about 32 MByte/s one-way with `ttcp` [UDP] between a 1.2GHz K7 and 2*500 Celeron (BP-6) through a plain crossover cable.
Not bad, but only 25% of wirespeed (125 MByte/sec). I figured the main limit was the PCI bus, which would only burst at 133 MByte/s, and I strongly suspected that the bursts were too short to achieve anything like this speed. I have yet to play with the PCI latency timer.
One thing for sure -- it isn't the CPU speed or Linux network stacks. The K7 will run both ends of ttcp through the localhost loopback at 570 MByte/s, and the BP6 around 200 MB/s.
There was another review of GigE performance in the IEEE Network Magazine last year.
D-Link's site is nearly impossible to navigate (maybe it requires JavaScript, which I've shut off), but the Pricewatch description of the DES-1009G indicates that Gigabit Ethernet is only available on one port as an uplink connection; the rest of the switch is your run-of-the-mill 10/100 job. The DGS-1008T is D-Link's 8-port unmanaged 10/100/1000 switch; the cheapest entry on Pricewatch for that is $595.
BTW, I have the entire site downloaded. Maybe I'm insane to even think about mirroring a /.'ed article on my home cable-modem link, but here it is. I've converted all the charts to PNG so they'll load slightly faster, and I got rid of most of the godawful "super-31337" yellow-on-black text to improve readability. You can also choose this link to download the entire page (images and all) in one shot.
20 January 2017: the End of an Error.
The fastest pci gets is 66mhz 64bit. Thats 64 bits per clock cycle, 66M clocks per second....4.224 Gigabits. I'd say thats a little higher than 1 Gb.