Chipsets (con't)

We have mentioned this in the past, but Opteron severely differs from Xeon due to the HyperTransport links from processor to processor, and that the memory controller is on the processor die. With each processor sharing a 6.4GB/s link to two other processors, and indirectly their memory banks, a four-way Opteron configuration does not get bottlenecked on a memory controller or Northbridge.

Most high end dual and quad Opteron solutions use two AMD 8131 PCI-X tunnels to control IO off the processors, but they go a step further by daisy-chaining a third 8131 tunnel to the secondary tunnel (which is why the V40z can utilize four 64-bit PCI-X 133MHz slots and still have enough IO for the integrated controllers). The HyperTransport specification details that five devices can be within an HT chain, so having two 8131 PCI-X tunnels daisy-chained is clearly within spec. A brief block diagram of our V40z can be found below.

Click to enlarge.

There is enough headroom on primary PCI-X tunnel for two more 100MHz PCI-X channels; and a third and slowest channel runs in tandem with the gigabit Ethernet and SCSI controller. Browsing through some online documentation revealed that the seventh, 66MHz PCI-X card shares bus resources with the LSI and Broadcom controllers, which means inserting a 33MHz PCI expansion card in the bus will reduce the operating bus of the SCSI and gigabit Ethernet controllers. Considering the 800MB/s headroom on that particular bus, it would seem like a poor choice to install a high bandwidth PCI device in the 66MHz interface anyway. Likewise, using a 66MHz and a 100MHz PCI-X device in tandem on the primary 8131 tunnel will result in both buses slowing to 66MHz.

AMD’s 8111 I/O Hub is linked off the primary 8131 PCI-X tunnel, and from there, most of the basic system functions are controlled including the XGI graphics adaptor. Even though XGI hasn’t been particularly popular on the desktop, Trident’s penetration into the server market solidified XGI’s server market share. The majority of the features on the AMD 8111 remain disabled, like AC’97 audio and the integrated 10/100 Ethernet controller.

Two Broadcom BCM703 chips control the external gigabit Ethernet for the server, but there are also two 10/100 out-of-band Ethernet ports that we will go into more depth later. Winbond provides the rest of the basic functionality of the machine not handled by the AMD 8111 I/O hub. LSI’s 53C1020 Ultra320 SCSI adaptor provides the V40z with the onboard SCSI.

Click to enlarge.

If the soul of our V40z is the Opteron 850, then the temporal lobe would be the Motorola MPC855T Service Processor. The Motorola MPC855T is a particularly interesting chip that we saved an entire page for more detail.

Detailing the Chipsets System Management: Another Linux Success


View All Comments

  • RyanVM - Tuesday, February 22, 2005 - link

    Did anybody else find it confusing that the reviewed system had CG-stepping Opteron 850s and Kris brought up E4-stepping Opteron 852s on multiple occasions? What CPUs were actually in the system? Reply
  • SUOrangeman - Tuesday, February 22, 2005 - link

    Last page, ..

    "Sun has a speed **daemon** on their hands, ..."

    Freudian slip, hehe? Nice read nonetheless.

  • KristopherKubicki - Tuesday, February 22, 2005 - link

    MrEMan: Mediaplex is just an advertising server. Some advertisers (like NewEgg) host their banners on Mediaplex so they don't destroy their bandwidth. Sometimes when an ad campaign is hitting too many impressions the Mediaplex tag will revert to a 2x2 or a 1x1 pixel so that they don't harm their click through rates. It has nothing to do with spyware or malware or adware.

  • MrEMan - Tuesday, February 22, 2005 - link


    What is with the 1/16" x 1/16" graphic (1280x1024 resolution on a 19" CRT monitor) for ?

    Is it there with your permission or did someone hack your site?

    If it is there with your permission, I must say I am surprised that you would put such stealth adware garbage links on your site.
  • jcourtney - Tuesday, February 22, 2005 - link

    I'd love to see some benchmarks with Solaris instead of or vs. Linux for reference too. Nice read though as usual. Reply
  • ElFenix - Tuesday, February 22, 2005 - link

    "particularly considering the fact that the V40z does not utilize any active cooling directly on their CPU heat sinks"

    whoa, proper spelling of heat sink!

    now i'm going to harp on the fact that blowing air across a radiator with a fan is not active cooling. air conditioning is active cooling, turning on the ceiling fan is not.


    nice read
  • Hikari - Tuesday, February 22, 2005 - link

    I wish I could see a comparison of this and that Quad Opteron HP server. I have the HP one budgeted for this year already... (we're also a Sun shop).

    I didn't see an option for 15k RPM drives though. I could put in like 5-146GB@15k RPM in the HP which was one reason I was leaning towards it.
  • lihoyin - Tuesday, February 22, 2005 - link

    Looking forward for a comparsion with HP DL585 / DL 385, both are also Monsters! Reply
  • Sunner - Tuesday, February 22, 2005 - link

    Googer, that's true, Sun basically just rebadges Newisys servers, the same is true of the V20Z, in fact IIRC you can actually find some Newisys marks left on the servers :)

    Anyway, Kris, any chance of a couple of benchmarks with a 2.6 based distro?
    2.6 has, among other things, good NUMA support, something that would be nice to have when running a 4-way Opteron ;)

  • dougSF30 - Tuesday, February 22, 2005 - link

    Another 250/850 typo on page 3: "Below, you can see one of the Opteron 250s is exposed from under the copper heat sink on the daughterboard."


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