16MB of L3 Cache: Intel’s “Tulsa”

Despite all the anticipation over Intel’s Core architecture and the market release of Core 2 Duo, Intel’s presence in the enterprise servers (four and more sockets) with NetBurst continues strong — although AMD is making some significant headway in this space.

According to Intel’s roadmaps, the first wave of Xeon MP processors based on Intel’s Tulsa core will be slated for Q4’06. Global Tech News has the following information on the 7100 series of Tulsa Xeon MP processors.  Tulsa is compatible with Socket 604, on Intel’s Truland platform.  Intel just announced its new LGA 771 socket, and it is not uncommon for Intel to produce multiple socket variants of processors during transition years.

Intel Server Processor Roadmap
Brand Processor
Clock Speed
Cache   Release

Xeon MP  
3.4GHz / 800MHz 16MB Q4’06

Xeon MP 
3.33GHz / 667MHz 16MB Q4’06
Xeon MP 
3.2GHz / 800MHz 8MB Q4’06
Xeon MP 
3.16GHz / 667MHz 8MB Q4’06
Xeon MP 
3.0GHz / 800MHz 4MB Q4’06
Xeon MP 
3.0GHz / 667MHz 4MB Q4’06
Xeon MP 
2.6GHz / 800MHz 4MB Q4’06
Xeon MP 
2.5GHz / 667MHz 4MB Q4’06

Xeon MP 7130 and 7140 will have a 150W power envelope, while 7110 and 7120 will use a 95W envelope.

The biggest feature of Tulsawill be large L3 cache sizes which range up to 16MB. These Tulsaprocessors are designed to scale to four and eight socket systems, and each Tulsa CPU contains two cores with HyperThreading support.  For those keeping track at home, an eight socket Paxville system will show 32 logical CPUs.

Tulsais the last of Intel’s Netburst lineup, but Netburst does have a few tricks not found on Core yet.  For starters, the massive amounts of L3 cache found in Tulsacores are shared between both cores. Each CPU has an independent L2 cache still.  AMD revealed earlier this year that K8L will also use the same ideology, with independent L2 and shared L3 cache. Intel has had shared L3 cache on its Itanium 2 server lineup for years, but this is the first time such a feature has appeared on x86.

This new shared cache has several advantages — each CPU core can use the L3 cache without sending a request back to the system I/O redundantly.  In order to manage errors in the cache, Intel has technology that already exists on Itantium 2, dubbed Pellston.  Intel has incorporated this onto Tulsa but renamed the technology to CST, or Cache Safe Technology.

Intel’s Woodcrest based Xeon processors expected to launch on June 26. These Woodcrest processors do not have HyperThreading, unlike Tulsa.  Dual-core Woodcrest processors have high front side bus speeds, shared L2 caches and use the Intel Core architecture.  However, Intel has no plans to replace NetBurst for Xeon servers that use more than two sockets — at least through Q2’07. 

In 2007, Intel will introduce Clovertown, a server varient of Kentsfield, Intel’s next-generation quad-core processor. Current Xeon MP processors based on Paxville will begin to be phased out by new Tulsacores, but the change will happen throughout most of 2007.  Intel just launched its Dempsey Xeon processors with fairly lackluster response.