Multiple Front Side Buses; Coming to an Intel Server Near You

Dissecting code names seems like a full time job for some of us lately.  Fortunately, a full time job pays for my schooling so here are the breakdown of Intel's newest code names, and what they mean to us.

Hopefully you have kept up with the last few articles from Anand and Jarred concerning dual core product SKUs and general Intel roadmaps.  Of course, processors are only half of Intel's business - core logic composes the less glamorous side of Intel.  Although we have been talking about Glenwood and Lakeport for several months now, today we are going to look at Intel's new server chipsets, Blackford and Greencreek.

Greencreek (also known as Greencreek 2S - 2Socket) is slated as the Tumwater (E7525) replacement, while Blackford is the Lindenhurst (E7520) replacement.  In short, the two chipsets are nearly identical with Blackford serving as the high end version of the platform. The large news here is Intel's push for dual front side buses.  The latest Intel roadmaps thoroughly describe dual independent buses as:
               "New 2S platform architecture for improved performance"
2S, of course, denotes 2 Sockets.  With advances towards dual core processing, the idea of independent buses per socket probably indicates the best approach possible for Intel to de-saturate the front side bus.  We already know that Twin Castle will utilize independent memory controllers, and with Greencreek/Blackford showing up soon after with dedicated paths to their memory controllers, we could see large boosts in memory IO.  The roadmap indicates Twin Castle will utilize multiple buses in later revisions as well.

Aside from dual buses, the new processors incorporate some other features as well, the largest being fully buffered DIMMs (FBD or FB-DIMM).  The Memory Forum actually has a very concise IDF presentation with the memory architecture explained here.  The apparent problem with DDR2 DIMMs (particularly when there are 8 or more) is that the signal gets very dirty.  FB-DIMM attempts to solve this by placing a memory buffer directly on the DIMM itself.  FB-DIMM aims to replace registered DIMMs, although the significant complexity of FBD will surely make it extremely expensive. 

Blackford/Greencreek also boast "enhanced storage controllers" (most likely SATA-II) and EM64T compatibility as well.  Below we have a small cross section on various chipset names and the details we know about them.

• Blackford: Lindenhurst successor for the Dempsey dual core processor. EM64T.  Dual Independent FSB.  FB-DIMM Support.  Scheduled for H1'06.
• Greencreek: Tumwater successor for the Dempsey dual core processor.  Will utilize two sockets.  EM64T. Dual Independent FSB.  FB-DIMM Support.  Scheduled for H1'06.
• Twin Castle: 4 Socket platform for Xeon MP.  Utilizes a dedicated memory controller.  Will probably support dual core processors with a future revision that supports multiple (or at least dual FSB).  Scheduled for Q1'06.
• Alviso: Intel's 915P chipset for the next generation Centrino platform.  Scheduled for Q1'05.
• Sonoma: Next generation Centrino platform including Alviso.  Scheduled for Q1'05.
• Napa: Successor for Sonoma designed for dual core mobility processors.  Adds DDR2-667.   Scheduled for Q1'06.
• Lakeport: 915P successor, supports 1066FSB, more PCIe lanes and 667MHz DDR-2, AMT and more EIST revisions.  Scheduled for Q2'05.
• Glenwood: 925XE successor.  Supports everything Lakeport does but should also include ECC capability.  Scheduled for launch with Lakeport.
• Tekoa:  Intel's next generation gigabit Ethernet chipset for deployment with Intel core logic.
• Mukilteo: Uniprocessor workstation release for the Glenwood/Lakeport generation.  Supports EM64T. 
• ICH7: Next generation south bridge.  Comes in several different versions including a "Raid" version, DH (Ditigal Home), DO (Digital Office), DE (Digital Enterprise) versions as well. 

Recently we have seen motherboard manufacturers disclose Pentium M platforms for the desktop.  As more and more people start adopting higher clocked Pentium Ms over Celerons and Pentium 4s, don't be surprised to hear a lot more people giving attention to all things Centrino.